docs(evidence): record clean capacity candidate (#18)

.dockerignore

@@ -0,0 +1,13 @@
+.git
+.gitea
+.idea
+.vs
+.codex
+.agents
+**/bin
+**/obj
+TestResults
+deploy/compose/secrets
+deploy/compose/.smoke.env
+docs
+tests

.gitea/workflows/ci.yml

@@ -35,3 +35,116 @@ jobs:
 
       - name: Test
         run: dotnet test Rendezvous.slnx --configuration Release --no-build
+
+      - name: Run quick capacity and resilience gate
+        run: ./scripts/run-capacity-gate.sh
+
+      - name: Test privileged Linux namespace topology when available
+        shell: bash
+        run: |
+          set -euo pipefail
+          probe="rendezvous-probe-$$"
+          suffix="$(( $$ % 100000 ))"
+          bridge="rvb${suffix}"
+          veth_root="rvr${suffix}"
+          veth_peer="rvp${suffix}"
+          cleanup_probe() {
+            if [[ -n "$veth_root" ]]; then
+              ip link delete "$veth_root" >/dev/null 2>&1 || true
+            fi
+            if [[ -n "$bridge" ]]; then
+              ip link delete "$bridge" >/dev/null 2>&1 || true
+            fi
+            if [[ -n "$probe" ]]; then
+              ip netns delete "$probe" >/dev/null 2>&1 || true
+            fi
+          }
+          trap cleanup_probe EXIT
+          if command -v ip >/dev/null 2>&1 \
+            && command -v iptables >/dev/null 2>&1 \
+            && command -v sysctl >/dev/null 2>&1 \
+            && ip netns add "$probe" 2>/dev/null \
+            && ip link add "$bridge" type bridge \
+            && ip link add "$veth_root" type veth peer name "$veth_peer" \
+            && ip link set "$veth_root" master "$bridge" \
+            && ip link set "$veth_peer" netns "$probe" \
+            && ip netns exec "$probe" sysctl -q -w net.ipv4.ip_forward=1 \
+            && ip netns exec "$probe" iptables -t nat -A POSTROUTING -o "$veth_peer" -j MASQUERADE \
+            && ip netns exec "$probe" iptables -A FORWARD -i "$veth_peer" -o lo \
+              -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT; then
+            ip link delete "$veth_root"
+            veth_root=""
+            ip link delete "$bridge"
+            bridge=""
+            ip netns delete "$probe"
+            probe=""
+            results="${RUNNER_TEMP:-/tmp}/rendezvous-netns-results"
+            mkdir -p "$results"
+            RENDEZVOUS_RUN_NETNS_TESTS=1 dotnet test Rendezvous.slnx \
+              --configuration Release \
+              --no-build \
+              --filter FullyQualifiedName~PrivilegedLinuxNatNamespacesCompleteDirectTrafficAcrossSeparateObservedEndpoints \
+              --logger "trx;LogFileName=netns.trx" \
+              --results-directory "$results"
+            grep -q 'testName="[^"]*\.PrivilegedLinuxNatNamespacesCompleteDirectTrafficAcrossSeparateObservedEndpoints"' \
+              "$results/netns.trx"
+          else
+            echo "Network namespaces/NAT tooling unavailable; deterministic loopback topology remains the required gate."
+          fi
+
+  container:
+    needs: quality
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Install .NET SDK
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: 10.0.301
+
+      - name: Build deployment diagnostic
+        run: |
+          dotnet restore src/FinalFactory.Rendezvous.TestClient/FinalFactory.Rendezvous.TestClient.csproj --locked-mode
+          dotnet build src/FinalFactory.Rendezvous.TestClient/FinalFactory.Rendezvous.TestClient.csproj --configuration Release --no-restore
+
+      - name: Build and exercise hardened container
+        shell: bash
+        run: |
+          set -euo pipefail
+          compose_file="deploy/compose/compose.yaml"
+          secret="deploy/compose/secrets/signing-key"
+          cleanup() {
+            RENDEZVOUS_UID=1654 RENDEZVOUS_GID=1654 \
+              docker compose -f "$compose_file" down --volumes >/dev/null 2>&1 || true
+            rm -f "$secret"
+          }
+          trap cleanup EXIT
+          install -d -m 0700 deploy/compose/secrets
+          openssl rand -out "$secret" 32
+          chmod 0444 "$secret"
+          export RENDEZVOUS_UID=1654
+          export RENDEZVOUS_GID=1654
+          docker compose -f "$compose_file" up --build --detach
+          container_id="$(docker compose -f "$compose_file" ps -q rendezvous)"
+          test -n "$container_id"
+          test "$(docker inspect --format '{{.Config.User}}' "$container_id")" = "1654:1654"
+          test "$(docker inspect --format '{{.HostConfig.ReadonlyRootfs}}' "$container_id")" = "true"
+          test "$(docker inspect --format '{{range .Mounts}}{{if eq .Destination \"/app/appsettings.Production.json\"}}{{.RW}}{{end}}{{end}}' "$container_id")" = "false"
+          test "$(docker inspect --format '{{range .Mounts}}{{if eq .Destination \"/run/secrets/rendezvous-signing-key\"}}{{.RW}}{{end}}{{end}}' "$container_id")" = "false"
+          for attempt in {1..100}; do
+            if curl --fail --silent http://127.0.0.1:8080/health/ready >/dev/null 2>&1; then
+              break
+            fi
+            if (( attempt == 100 )); then
+              docker compose -f "$compose_file" logs rendezvous
+              exit 1
+            fi
+            sleep 0.1
+          done
+          ./scripts/smoke-deployment.sh
+          docker compose -f "$compose_file" stop --timeout 40 rendezvous
+          test "$(docker inspect --format '{{.State.Running}}' "$container_id")" = "false"
+          test "$(docker inspect --format '{{.State.ExitCode}}' "$container_id")" = "0"

.gitignore

@@ -6,3 +6,7 @@ TestResults/
 *.suo
 *.user
 *.userosscache
+deploy/compose/.smoke.env
+artifacts/
+deploy/compose/secrets/*
+!deploy/compose/secrets/.gitignore

Dockerfile

@@ -0,0 +1,30 @@
+# syntax=docker/dockerfile:1.7@sha256:a57df69d0ea827fb7266491f2813635de6f17269be881f696fbfdf2d83dda33e
+FROM mcr.microsoft.com/dotnet/sdk:10.0.301-noble@sha256:ea8bde36c11b6e7eec2656d0e59101d4462f6bd630730f2c8201ed0572b295d5 AS build
+
+WORKDIR /source
+COPY Directory.Build.props Directory.Packages.props NuGet.config global.json Rendezvous.slnx ./
+COPY src/FinalFactory.Rendezvous.Contracts/FinalFactory.Rendezvous.Contracts.csproj src/FinalFactory.Rendezvous.Contracts/packages.lock.json src/FinalFactory.Rendezvous.Contracts/
+COPY src/FinalFactory.Rendezvous.Server/FinalFactory.Rendezvous.Server.csproj src/FinalFactory.Rendezvous.Server/packages.lock.json src/FinalFactory.Rendezvous.Server/
+RUN dotnet restore src/FinalFactory.Rendezvous.Server/FinalFactory.Rendezvous.Server.csproj --locked-mode
+
+COPY src/FinalFactory.Rendezvous.Contracts/ src/FinalFactory.Rendezvous.Contracts/
+COPY src/FinalFactory.Rendezvous.Server/ src/FinalFactory.Rendezvous.Server/
+RUN dotnet publish src/FinalFactory.Rendezvous.Server/FinalFactory.Rendezvous.Server.csproj \
+    --configuration Release \
+    --no-restore \
+    --output /out \
+    /p:UseAppHost=false \
+    /p:OpenApiGenerateDocuments=false
+
+FROM mcr.microsoft.com/dotnet/aspnet:10.0.9-noble-chiseled@sha256:f820c4fbfb8bb204c3bbe05c69d48cd039cd0e67aa8f13ac1cec168819b90643 AS runtime
+
+ENV ASPNETCORE_HTTP_PORTS=8080 \
+    DOTNET_EnableDiagnostics=0 \
+    DOTNET_CLI_TELEMETRY_OPTOUT=1 \
+    TMPDIR=/tmp
+WORKDIR /app
+COPY --from=build --chown=1654:1654 /out/ ./
+USER 1654:1654
+EXPOSE 8080/tcp
+EXPOSE 9050/udp
+ENTRYPOINT ["dotnet", "FinalFactory.Rendezvous.Server.dll"]

README.md

@@ -17,7 +17,7 @@ Rendezvous is intended to provide:
 - Isolation by game, environment, protocol version, and region.
 - Operational health, metrics, logging, administration, and rate limiting.
 
-UDP hole punching cannot guarantee a direct connection through every network. Symmetric NAT, carrier-grade NAT, restrictive firewalls, and platform policies can prevent it. Consumers must therefore support a defined fallback, such as a dedicated server or a future relay service.
+UDP hole punching cannot guarantee a direct connection through every network. Symmetric NAT, carrier-grade NAT, restrictive firewalls, and platform policies can prevent it. Consumers must therefore support a defined fallback, such as a dedicated server. The v1 SDK returns an optional game-configured endpoint for an explicit caller decision; it never routes automatically, and v1 does not provide a relay.
 
 ## Connection flow
 
@@ -38,7 +38,11 @@ UDP hole punching cannot guarantee a direct connection through every network. Sy
 - `FinalFactory.Rendezvous.TestClient` — thin interactive and scriptable host/browser/join diagnostic built only on the public SDK.
 - `FinalFactory.Rendezvous.Tests` — unit, integration, security, and connection-lifecycle tests.
 
-The server directory and NAT mediator begin as separate modules in one deployable service because they share session, lease, authorization, and endpoint state. Their internal boundary should allow independent deployment later if scale, availability, or security requirements diverge.
+The server directory and NAT mediator are separate modules in one single-active
+deployable service because they share ephemeral session, lease, authorization,
+replay, and endpoint state. Their internal boundary can support a future
+explicitly designed shared-state architecture; operators must not create
+multiple active v1 replicas.
 
 ## Service boundaries
 
@@ -75,7 +79,15 @@ The initial service does not provide:
 
 ## Project status
 
-Rendezvous is currently in its initial design and bootstrap stage. The first implementation should establish the contracts, directory leases, LiteNetLib mediator, client SDK, thin test client, and a three-party integration test before either game depends on it for production connectivity.
+Rendezvous is under active roadmap development. The versioned contracts,
+directory leases, authenticated join attempts, LiteNetLib mediator, caller-owned
+SDK coordination, typed connection outcomes, thin public-SDK diagnostic client,
+deterministic NAT topology harness, hostile-input controls,
+observability/operator surface, secure single-active Linux deployment, and
+numeric capacity/resilience gates are implemented. Packaging, consumer pilots,
+and final production-readiness gates remain in progress;
+participating games must not treat the current repository as a finished production
+service until those gates land.
 
 The ratified v1 boundaries, trust decisions, privacy rules, safety budgets, and
 threat model are indexed in [the architecture documentation](docs/architecture/README.md).
@@ -83,6 +95,22 @@ The frozen v1 wire surface is documented in the
 [HTTP, UDP, and generated OpenAPI contracts](docs/contracts/README.md).
 Tenant policy, publisher/operator principals, and production key custody are
 defined in [game provisioning and signing-key lifecycle](docs/security/provisioning.md).
+Layered HTTP/UDP budgets, overload behavior, and safe operational tuning are
+defined in [hostile-input and overload protection](docs/security/abuse-protection.md).
+Health semantics, bounded telemetry, alerting, audit privacy, and the authenticated
+operator controls are defined in the
+[observability and operator runbook](docs/operations/observability-and-operator-runbook.md).
+The pinned non-root container, production topology, graceful drain, Linux
+hardening, smoke procedure, and recovery lifecycle are documented in
+[secure single-active Linux deployment](docs/deployment/linux.md).
+The numeric core-state candidate profile, public launch objectives, accelerated
+soak, resilience matrix, and single-active scaling decision are recorded in
+[capacity and resilience gates](docs/operations/capacity-and-resilience.md).
+The scriptable host/browser/join diagnostic and its stable automation contract are
+documented in the [TestClient integration guide](docs/integration/test-client.md).
+The always-on three-party scenarios, optional Linux namespace topology, and
+simulation limits are documented in the
+[deterministic topology harness](docs/integration/topology-harness.md).
 
 ## Development
 
@@ -99,9 +127,11 @@ dotnet test Rendezvous.slnx --configuration Release --no-build
 Run the bootstrap server with
 `dotnet run --project src/FinalFactory.Rendezvous.Server`. It serves HTTP health endpoints and binds
 the configured UDP mediator port; both stop through normal host cancellation.
-The launch profile uses an ephemeral development-only signing key. Production
-startup fails closed until externally supplied game policies and `env:` signing
-key references resolve to valid key material; no reusable game secret is stored
+The launch profile uses separate ephemeral development-only publisher and operator
+signing keys. Production
+startup fails closed until its advertised endpoints, proxy trust boundary,
+externally supplied game policies, and `env:` (base64) or `file:` (raw,
+absolute, non-symlink) signing-key references resolve safely; no reusable game secret is stored
 in this repository or the public Client package.
 The project dependency rules and supported runtime choices are documented in
 [project and dependency boundaries](docs/architecture/project-boundaries.md).

Rendezvous.slnx

@@ -6,6 +6,7 @@
     <Project Path="src/FinalFactory.Rendezvous.TestClient/FinalFactory.Rendezvous.TestClient.csproj" />
   </Folder>
   <Folder Name="/tests/">
+    <Project Path="tests/FinalFactory.Rendezvous.Capacity/FinalFactory.Rendezvous.Capacity.csproj" />
     <Project Path="tests/FinalFactory.Rendezvous.Tests/FinalFactory.Rendezvous.Tests.csproj" />
   </Folder>
 </Solution>

deploy/compose/appsettings.Production.json

@@ -0,0 +1,58 @@
+{
+  "AllowedHosts": "localhost;127.0.0.1",
+  "Rendezvous": {
+    "Deployment": {
+      "PublicHttpBaseUrl": "https://localhost/",
+      "PublicUdpHost": "127.0.0.1",
+      "PublicUdpPort": 9050,
+      "DrainDeadlineSeconds": 30,
+      "MinimumDrainSeconds": 1,
+      "SingleActiveInstance": true,
+      "AllowPrivatePublicEndpoints": true
+    },
+    "Udp": {
+      "ListenAddress": "0.0.0.0",
+      "Port": 9050
+    },
+    "AbuseProtection": {
+      "TrustedProxyAddresses": ["127.0.0.1"],
+      "OperatorAllowedAddresses": ["127.0.0.1"]
+    },
+    "Provisioning": {
+      "Issuer": "final-factory-rendezvous-smoke",
+      "Audience": "rendezvous-service",
+      "ClockSkewSeconds": 30,
+      "SigningKeys": [
+        {
+          "KeyId": "local-smoke-1",
+          "SecretReference": "file:/run/secrets/rendezvous-signing-key",
+          "CredentialKinds": ["DedicatedPublisher"],
+          "GameId": "space-game",
+          "EnvironmentId": "smoke",
+          "NotBefore": "2026-01-01T00:00:00Z",
+          "SignUntil": "2100-01-01T00:00:00Z",
+          "VerifyUntil": "2100-01-02T00:00:00Z"
+        }
+      ],
+      "Games": [
+        {
+          "GameId": "space-game",
+          "EnvironmentId": "smoke",
+          "Enabled": true,
+          "ProtocolVersions": [1],
+          "Regions": ["local"],
+          "VisibilityModes": ["Public"],
+          "PublisherTrustModes": ["ManagedDedicated"],
+          "MetadataValueMaxBytes": {},
+          "RequiredMetadataKeys": [],
+          "MetadataMaxBytes": 512,
+          "MetadataMaxKeys": 0,
+          "MaxListingsPerPrincipal": 10,
+          "MaxAnonymousListingsPerAddress": 0,
+          "MaxActiveJoinAttempts": 100,
+          "FallbackPolicy": "Disabled"
+        }
+      ]
+    }
+  }
+}

deploy/compose/compose.yaml

@@ -0,0 +1,35 @@
+name: rendezvous-local
+
+services:
+  rendezvous:
+    image: finalfactory/rendezvous:local
+    build:
+      context: ../..
+      dockerfile: Dockerfile
+    init: true
+    user: "${RENDEZVOUS_UID:?set RENDEZVOUS_UID to a non-root host UID}:${RENDEZVOUS_GID:?set RENDEZVOUS_GID to its GID}"
+    read_only: true
+    tmpfs:
+      - /tmp:rw,noexec,nosuid,nodev,size=16m,uid=${RENDEZVOUS_UID},gid=${RENDEZVOUS_GID},mode=0700
+    cap_drop:
+      - ALL
+    security_opt:
+      - no-new-privileges:true
+    pids_limit: 128
+    mem_limit: 512m
+    cpus: 1.0
+    ulimits:
+      nofile:
+        soft: 4096
+        hard: 4096
+    stop_grace_period: 40s
+    restart: unless-stopped
+    environment:
+      ASPNETCORE_ENVIRONMENT: Production
+      ASPNETCORE_HTTP_PORTS: "8080"
+    volumes:
+      - ./appsettings.Production.json:/app/appsettings.Production.json:ro
+      - ./secrets/signing-key:/run/secrets/rendezvous-signing-key:ro
+    ports:
+      - "127.0.0.1:8080:8080/tcp"
+      - "9050:9050/udp"

deploy/compose/secrets/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

deploy/systemd/rendezvous.service

@@ -0,0 +1,48 @@
+[Unit]
+Description=Final Factory Rendezvous service
+Documentation=https://git.finalfactory.de/HeiKyu/Rendezvous
+After=network-online.target time-sync.target
+Wants=network-online.target time-sync.target
+
+[Service]
+Type=simple
+User=rendezvous
+Group=rendezvous
+WorkingDirectory=/opt/rendezvous
+ExecStart=/usr/bin/dotnet /opt/rendezvous/FinalFactory.Rendezvous.Server.dll
+Environment=ASPNETCORE_ENVIRONMENT=Production
+Environment=ASPNETCORE_HTTP_PORTS=8080
+Environment=DOTNET_EnableDiagnostics=0
+EnvironmentFile=-/etc/rendezvous/rendezvous.env
+Restart=on-failure
+RestartSec=5s
+KillSignal=SIGTERM
+KillMode=mixed
+TimeoutStopSec=40s
+NoNewPrivileges=true
+PrivateDevices=true
+PrivateTmp=true
+ProtectClock=true
+ProtectControlGroups=true
+ProtectHome=true
+ProtectHostname=true
+ProtectKernelLogs=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectSystem=strict
+RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
+RestrictNamespaces=true
+RestrictRealtime=true
+RestrictSUIDSGID=true
+CapabilityBoundingSet=
+AmbientCapabilities=
+LockPersonality=true
+SystemCallArchitectures=native
+UMask=0077
+LimitNOFILE=4096
+CPUQuota=200%
+MemoryMax=2G
+TasksMax=128
+
+[Install]
+WantedBy=multi-user.target

docs/architecture/0003-state-privacy-availability-and-budgets.md

@@ -129,9 +129,18 @@ until the owner records:
 - which games may enable anonymous unlisted player hosting;
 - deployment regions, data-processing jurisdiction, and approval of the stated
   30-day audit/13-month aggregate retention periods;
-- the per-game dedicated fallback endpoint policy;
-- the measured supported profile and whether the 99.5% single-active objective
-  is sufficient or shared-state/high-availability work must be brought forward.
+- the per-game dedicated fallback endpoint policy.
+
+Issue #18 measured and ratified the original 2-vCPU/2-GiB, 25,000-listing,
+10,000-attempt core-state candidate profile and retained the 99.5% single-active
+topology. It does not claim that core measurements prove public HTTP/UDP SLOs.
+The versioned evidence, RTO, failure domains, and explicit signals that trigger
+shared-state/high-availability work are recorded in the
+[capacity and resilience gate](../operations/capacity-and-resilience.md). The
+real-network canary in #23 must confirm that the proposed regional launch load
+fits this profile and validate the public SLOs; it may lower the launch cap but
+may not silently enable a
+second active instance.
 
 These are configuration and launch decisions, not permission to weaken the
 tenant, replay, endpoint-verification, or secret-handling controls.

docs/architecture/0008-scoped-join-attempts-and-tickets.md

@@ -24,18 +24,24 @@ credentials plus opaque attempt and mediation IDs from a process-ephemeral HMAC
 key, the client subject, the complete canonical request fingerprint, a fresh salt,
 and a purpose/role label. Credentials are 32-byte base64url values (43 characters),
 below both the 192-character Rendezvous capability ceiling and LiteNetLib's
-256-character NAT token ceiling. State retains keyed credential fingerprints,
-derivation inputs, and salt—not issued plaintext. All diagnostic string
-representations redact credentials and derivation material.
+256-character NAT token ceiling. The connection ticket uses half of that payload
+for its attempt ID and half for an independently derived 128-bit authenticator, so
+the SDK can correlate concurrent introductions without increasing UDP response
+size. State retains keyed credential fingerprints, derivation inputs, and salt—not
+issued plaintext. All diagnostic string representations redact credentials and
+derivation material.
 
 The client receives only its punch capability. A host polls its own listing with
 the lease token in `X-Rendezvous-Lease-Token` and receives only host-role
 capabilities through a signed, listing-bound, five-minute cursor. Replaying an
 identical join request returns the same live attempt; changing the request under
 the same owner/key conflicts. A client may cancel with its punch capability in
-`X-Rendezvous-Client-Punch-Capability`; cancellation atomically removes the
-attempt. Listing deletion, expiry, revocation, or process restart removes every
-associated attempt and credential fingerprint.
+`X-Rendezvous-Client-Punch-Capability`; cancellation atomically marks the attempt
+and retains a bounded tombstone until its original expiry. Host polling returns
+that tombstone so a coordinator can revoke any local ticket authorization, while
+endpoint binding, introduction, ticket issuance, and ticket consumption all
+reject the cancelled attempt. Listing deletion, expiry, revocation, or process
+restart removes every associated attempt and credential fingerprint.
 
 Endpoint binding remains role- and capability-specific. The first endpoint
 observed for a role wins atomically; an exact UDP duplicate is idempotent, while
@@ -50,8 +56,14 @@ fingerprint-consumption seam for mediator tests and revocation. On the game host
 the SDK's bounded `ConnectionTicketValidator` stores a process-keyed digest,
 accepts an exact ticket once under a lock, rejects altered/cross-attempt/expired/
 revoked/replayed tickets, and zeroes retained digests and key material on disposal.
-Issue #11 carries the ticket in the authenticated introduction; issue #12 wires
-authorization and consumption into the caller-owned LiteNetLib coordinator.
+Issue #11 carries the fixed-size ticket in the authenticated introduction. Issue
+#12 extracts its embedded attempt ID, bounds the host's local authorization window
+by both the host-polled attempt expiry and the configured ticket lifetime, then
+wires one-time consumption into the caller-owned coordinator. Both peers receive
+a digest of the exact expected ticket over HTTP and reject any syntactically valid
+but unauthenticated introduction token. Embedding the ID prevents concurrent or
+late introductions from cross-binding a valid ticket while preserving the
+mediator's 2.0 response-byte amplification ceiling.
 
 ## Consequences
 

docs/architecture/0010-typed-connection-outcomes-and-fallback.md

@@ -0,0 +1,117 @@
+# ADR 0010: typed connection outcomes, deadlines, and caller-owned fallback
+
+- Status: Accepted
+- Date: 2026-07-16
+- Tracking: #13
+
+## Context
+
+A connection can stop in the directory, authorization, mediation, NAT traversal,
+or direct-connection phase. Those failures have different authorities: an HTTP
+response can authoritatively reject a join, the SDK can observe a local timeout,
+and only the remote host can reject a direct connection. Treating all of them as
+one message or generic timeout would make player guidance, retry policy, tests,
+and operational measurements unreliable.
+
+UDP loss, service silence, cancellation, and late LiteNetLib callbacks also make
+completion races unavoidable. Games need one terminal result and bounded work,
+not a sequence of contradictory callbacks. Direct traversal cannot be guaranteed,
+but v1 has no gameplay relay and must not imply otherwise.
+
+## Decision
+
+### Closed typed outcome model
+
+`ConnectionOutcomeKind` is the stable wire-level terminal set: connected,
+cancelled, directory not found, attempt expired, incompatible protocol,
+unauthorized, rate limited, no host presence, service unavailable or rejected,
+mediator unavailable, punch timeout, direct-connect timeout, host rejection,
+transport error, manager stopped, and disposed.
+
+The already-frozen v1 members `TimedOut`, `StaleHost`, `TransportFailed`, and
+`FallbackOffered` retain their original numeric values for source and wire
+compatibility. New SDK code never emits them. The report service accepts them,
+normalizes the first three to their precise modern equivalents, and does not let
+legacy compatibility weaken the typed coordinator result.
+
+The client adds `RendezvousConnectionOutcomeSource`, failure category, and phase.
+These fields preserve authority instead of guessing from text:
+
+- `RendezvousService` is used only for an HTTP decision or bounded service
+  silence. Its optional `ServiceError` retains the stable service error code.
+- `LocalTraversal` reports local punch, direct-connect, and transport
+  observations.
+- `RemoteHost` reports an explicit direct-connection rejection.
+- `Caller` and `Lifecycle` distinguish cancellation from manager shutdown or
+  disposal.
+
+Messages remain diagnostic and are never parsed into outcomes. A successful NAT
+introduction is only a transition to direct connection; `Connected` is emitted
+only after LiteNetLib reports the authenticated peer connected.
+
+Join issuance is exposed as `RendezvousConnectionStartResult`, containing exactly
+one issued attempt or one terminal service outcome. Once an attempt is issued,
+the coordinator owns its local terminal outcome. Completion is exactly once;
+terminal paths release SDK subscriptions so late introductions, peer callbacks,
+network errors, cancellation, and polling are inert.
+
+### Bounded phases and retries
+
+Each HTTP try has a five-second default silence budget, configurable from above
+zero through thirty seconds. Only safe operations use the existing bounded retry
+policy, honoring caller cancellation and server retry guidance. Exhausting that
+budget returns `ServiceUnavailable`; it never waits indefinitely.
+
+Traversal has independent defaults: ten seconds for punch/mediation and five
+seconds for the direct connection. Both are configurable up to thirty seconds.
+Local budgets, retry schedules, and elapsed duration use monotonic time, so a
+wall-clock correction cannot extend them or produce a negative duration. The
+signed attempt expiry is converted to an additional monotonic upper bound when
+the attempt is received. Punch retries retain
+their bounded request count and exponential backoff; crossing a phase deadline
+completes exactly once even if a delayed packet later arrives. Tests use an
+injected clock and do not depend on wall-clock sleeps.
+
+### Explicit dedicated fallback handoff
+
+A publisher may attach one validated dedicated endpoint to registration or
+update only when the tenant's provisioned fallback policy allows it. The server
+copies that endpoint into browser and issued-attempt contracts.
+The client coordinator defensively copies it into every terminal outcome; a game
+may override it locally through `DedicatedFallbackOverride`.
+
+The SDK never opens, dials, reserves, probes, or authenticates the fallback. The
+game decides whether the outcome permits fallback, presents any player choice,
+and connects through its own gameplay transport and admission rules. Absence of
+an endpoint is an honest no-fallback result. Gameplay relay is absent from v1.
+
+### Privacy-safe optional reporting
+
+After an issued attempt completes, the game may explicitly report its outcome
+with the short-lived client punch capability. Reporting is authenticated and
+idempotent: an exact repeat succeeds as a duplicate, while a conflicting repeat
+is rejected. Reports contain only an allowlisted outcome enum and one coarse
+elapsed bucket (`<1s`, `1–5s`, `5–15s`, `15–30s`, or `30s+`). They contain no
+diagnostic message, exact duration, endpoint, metadata, player identifier, or
+credential.
+
+Frozen v1 DTOs still expose `elapsedMilliseconds` and `diagnosticCode`. They are
+deprecated compatibility inputs: the current SDK omits them, the service
+immediately buckets legacy elapsed time, and neither exact timing nor diagnostic
+text is retained, logged, or used as a metric dimension.
+
+The store retains a bounded capability-fingerprint tombstone long enough to
+accept a report after the live attempt expires. Metrics count the first accepted
+outcome only and use only outcome plus elapsed bucket as dimensions. Service
+issuance failures cannot be reported because no attempt capability was issued.
+
+## Consequences
+
+- Player-facing UI can map stable outcome/category pairs to localized guidance
+  without exposing diagnostic strings.
+- Service rejection, remote-host rejection, and local observation remain
+  distinguishable for retry and support decisions.
+- Games own fallback policy and gameplay admission; Rendezvous does not claim a
+  guaranteed connection path.
+- Outcome additions are contract changes and require OpenAPI, serialization,
+  public API, fake-clock, late-event, and idempotency coverage.

docs/architecture/README.md

@@ -12,6 +12,7 @@ decision requires a superseding ADR and corresponding contract/test updates.
 - [ADR 0007: caller-owned .NET publisher and browser SDK](0007-caller-owned-dotnet-client-sdk.md)
 - [ADR 0008: scoped join attempts and one-time connection tickets](0008-scoped-join-attempts-and-tickets.md)
 - [ADR 0009: authenticated bounded LiteNetLib NAT mediator](0009-authenticated-litenet-nat-mediator.md)
+- [ADR 0010: typed connection outcomes, deadlines, and caller-owned fallback](0010-typed-connection-outcomes-and-fallback.md)
 - [Threat model](../security/threat-model.md)
 - [Security promise and test matrix](../security/control-matrix.md)
 - [Versioned HTTP and UDP contracts](../contracts/README.md)

docs/contracts/http-v1.md

@@ -40,9 +40,7 @@ the same value as a required query parameter.
 | `GET` | `/health/ready` | Report whether the UDP mediator is bound and ready. |
 
 The generated [OpenAPI document](../api/rendezvous-v1.json) is the normative
-shape reference for parameters, bodies, and responses. Contract-only endpoints
-return `501` until their behavior is implemented by the subsequent directory,
-lease, and join-orchestration issues.
+shape reference for parameters, bodies, and responses.
 
 Host polling sends its reusable lease credential in
 `X-Rendezvous-Lease-Token`; it must never be placed in a URL. Lease credentials
@@ -55,6 +53,24 @@ Attempt cancellation sends the short-lived client punch capability in
 source only for a process-keyed, short-lived idempotency/abuse scope; this is not
 player authentication and is never returned to callers.
 
+Outcome reporting uses that same short-lived capability. It accepts only outcomes
+for an issued attempt and carries one stable outcome enum plus one coarse elapsed
+bucket. Exact duplicate reports are idempotent; conflicting repeats fail. Reports
+never carry exact timing, diagnostics, endpoints, metadata, player identifiers,
+or credentials.
+
+The frozen v1 .NET request also retains deprecated `elapsedMilliseconds` and
+`diagnosticCode` properties for source/wire compatibility. Current clients omit
+them. If a legacy client supplies them, the server immediately converts elapsed
+milliseconds to the coarse bucket and discards diagnostic text; neither value is
+retained or used as a metric dimension.
+
+Registration and update may include one validated `dedicatedFallback`. The
+endpoint must be enabled by the tenant's provisioned fallback policy, is visible
+browser data, and is copied into subsequently issued attempts.
+It is a handoff for caller-owned policy: neither the HTTP service nor the SDK
+automatically connects to it. V1 provides no gameplay relay.
+
 ## Idempotency, cursors, and retries
 
 Registration and join creation require a caller-generated visible-ASCII
@@ -101,9 +117,9 @@ must not be parsed. Secrets and raw credentials are never echoed.
 | 401 | `authenticationRequired` |
 | 403 | `forbidden` |
 | 404 | `notFound` |
-| 409 | `conflict`, `incompatibleProtocol`, `replayRejected`, `capacityExceeded` |
+| 409 | `conflict`, `incompatibleProtocol`, `replayRejected` |
 | 410 | `expired`, `staleHost` |
-| 429 | `rateLimited` (with retry guidance when known) |
+| 429 | `rateLimited`, `capacityExceeded` (with retry guidance when known) |
 | 503 | `serviceUnavailable` (with retry guidance when known) |
 | 500 | `internalError` |
 

docs/deployment/linux.md

@@ -0,0 +1,228 @@
+# Secure single-active Linux deployment
+
+Tracking: #17
+
+Rendezvous v1 stores listings, observed endpoints, join attempts, replay markers,
+and runtime revocations only in the process that accepted them. Deploy exactly
+one active instance. A second live replica would have a different directory and
+replay boundary; `SingleActiveInstance=false` is therefore rejected rather than
+presented as high availability.
+
+## Pinned container
+
+The root `Dockerfile` uses a multi-stage .NET 10 build and pins both Microsoft
+base images by multi-architecture manifest digest. The runtime is the chiseled
+ASP.NET image, contains only the published server, runs as UID/GID 1654, exposes
+TCP 8080 and UDP 9050 explicitly, and does not require a writable application
+directory. Supply a small writable `/tmp` tmpfs because runtime libraries can
+legitimately need temporary space; keep the root filesystem read-only.
+
+From a clean checkout:
+
+```bash
+docker build --pull=false --tag finalfactory/rendezvous:local .
+docker inspect --format '{{.Config.User}}' finalfactory/rendezvous:local
+```
+
+The reported user must be `1654:1654`. Digest pins make a rebuild reproducible;
+updating .NET is an explicit reviewed change to the tag, digest, SDK pin, and
+lock files together. Do not replace the digest with `latest` in production.
+
+The local Compose example applies a read-only root, non-root user, no Linux
+capabilities, `no-new-privileges`, bounded PIDs/files/memory/CPU, and a shutdown
+grace period longer than the service drain deadline:
+
+```bash
+install -d -m 0700 deploy/compose/secrets
+umask 077
+openssl rand -out deploy/compose/secrets/signing-key 32
+export RENDEZVOUS_UID="$(id -u)"
+export RENDEZVOUS_GID="$(id -g)"
+test "$RENDEZVOUS_UID" -ne 0
+docker compose -f deploy/compose/compose.yaml up --build --detach
+```
+
+`deploy/compose/appsettings.Production.json` is an isolated loopback smoke
+profile, not an Internet template: it deliberately opts into private advertised
+endpoints and has no TLS proxy. Its random key is ignored by Git and must be
+deleted after use. Its deliberately long key window only keeps this disposable
+local fixture usable; production keys require short, reviewed rotation windows.
+Production configuration must use its real public names and must leave
+`AllowPrivatePublicEndpoints` false.
+
+## Production topology
+
+Use one active service behind a source-preserving edge:
+
+```text
+clients -- HTTPS/443 --> TLS reverse proxy -- HTTP/8080 --> Rendezvous
+clients -- UDP/9050 -------------------------------------> Rendezvous
+```
+
+- Give the HTTPS origin and UDP endpoint stable DNS names. Set
+  `PublicHttpBaseUrl` to the exact external HTTPS origin and `PublicUdpHost` /
+  `PublicUdpPort` to the endpoint given to game clients.
+- Terminate TLS 1.2 or newer at a maintained reverse proxy. Bind internal HTTP
+  only to the private proxy network. Restrict `AllowedHosts` to the public HTTP
+  host; wildcard host filtering is rejected.
+- Put only the proxy's exact literal addresses in
+  `Rendezvous:AbuseProtection:TrustedProxyAddresses`. Rendezvous ignores
+  forwarded headers from every other source. Keep the last proxy from replacing
+  the original client address and prevent direct access to TCP 8080.
+- Forward UDP as UDP, without an HTTP proxy. NAT, load balancer, firewall, and
+  return routing must preserve the client's source IP/port and must send replies
+  from the same advertised IP/port. Many HTTP load balancers, Kubernetes ingress
+  controllers, rootless container port proxies, anycast products, and generic
+  L7 services cannot guarantee this. Do not deploy through one unless an actual
+  host/join smoke proves both observed source and reply path. A load balancer
+  must have exactly one healthy Rendezvous target.
+- Permit inbound TCP 443 to the TLS proxy and UDP 9050 to Rendezvous. Permit the
+  proxy to reach TCP 8080. Permit DNS, time synchronization, image/telemetry
+  destinations as required by local policy, and UDP replies to client endpoints.
+  Deny public TCP 8080 and every unused inbound port.
+
+Readiness is the load-balancer gate; liveness is only a process-health signal.
+Remove a draining instance from new traffic when `/health/ready` becomes 503.
+Do not use liveness failure to start a second active process while the old one
+still owns the public UDP address.
+
+## Required production configuration
+
+Production startup validates all of these before binding listeners:
+
+- an absolute path-free HTTPS `PublicHttpBaseUrl`;
+- an unambiguous public `PublicUdpHost` and port;
+- `SingleActiveInstance=true`, an explicit non-wildcard `AllowedHosts`, and at
+  least one exact trusted TLS-proxy address;
+- a 1-30 second drain deadline whose minimum observation interval is shorter;
+- at least one enabled game policy and an active scoped signing key.
+
+Missing values produce an actionable startup error. The checked-in base file is
+intentionally unsafe for Production so an accidental bare launch fails closed.
+
+Signing keys support two external references:
+
+- `env:NAME` reads 1-4096 bytes encoded as base64 from `NAME`;
+- `file:/absolute/path` reads 1-4096 raw bytes from a non-symlink file.
+
+Prefer a read-only container secret owned by the configured container identity.
+For systemd, use a root-owned, `rendezvous`-group-owned `0440` file (or an
+equivalent narrow ACL) so the non-root process can read but not replace it. A
+signing key must contain at least 32 random bytes. Never put the key, publisher/operator
+credential, or secret value in JSON, a command argument, an image layer, Compose
+environment, logs, metrics, or source control. Configuration contains only the
+reference and non-secret lifecycle metadata. A vault/KMS adapter can replace the
+provider where local policy requires it.
+
+Keep the host clock synchronized with authenticated NTP. Credential and key
+windows use wall time; lease, timeout, drain, and rate-limit deadlines use a
+monotonic clock. Alert on clock synchronization loss before rotating keys.
+
+The checked-in Compose limits (one CPU and 512 MiB) are for its isolated smoke
+profile, not a production capacity claim. The measured core-state candidate
+uses 2 vCPU and 2 GiB with the same 128-PID/4096-descriptor ceilings; see
+the [capacity and resilience gate](../operations/capacity-and-resilience.md).
+Measure real traffic, then change resource limits and server budgets together.
+Memory pressure or CPU throttling must not extend orchestrator termination past
+`DrainDeadlineSeconds` plus five seconds.
+
+## Graceful shutdown
+
+SIGTERM and the authenticated operator drain both stop new registrations and
+join attempts immediately. On process shutdown, HTTP and UDP remain available
+long enough for existing join attempts to finish. The service exits as soon as
+the minimum drain interval has elapsed and no attempts remain, or forcibly
+clears all ephemeral state at the configured deadline. It then stops UDP and
+HTTP listeners and exits. Configure Docker/systemd/Kubernetes termination grace
+strictly longer than the service deadline; the examples use 40 seconds for a
+30-second drain.
+
+Never use SIGKILL for a normal rollout. After stopping, verify the process is
+gone and neither `8080/tcp` nor `9050/udp` is bound before starting its
+replacement on the same host. A crashed or force-killed process cannot drain;
+clients recover through bounded retries and hosts re-register.
+
+## systemd alternative
+
+Publish the server for Linux, install the immutable output at `/opt/rendezvous`,
+place production configuration beside the application read-only, place key
+files below `/etc/rendezvous`, and install `deploy/systemd/rendezvous.service`:
+
+```bash
+dotnet publish src/FinalFactory.Rendezvous.Server \
+  --configuration Release --runtime linux-x64 --self-contained false \
+  --output publish/rendezvous
+systemd-analyze verify deploy/systemd/rendezvous.service
+sudo systemctl daemon-reload
+sudo systemctl enable --now rendezvous.service
+```
+
+Create the dedicated `rendezvous` user without a login shell. Keep
+`/opt/rendezvous` and `/etc/rendezvous` root-owned and non-writable by that user;
+install each required key with `root:rendezvous` ownership and mode `0440`. The
+unit applies the measured 2-vCPU/2-GiB core-state candidate profile plus the
+same filesystem, privilege, network-family, and shutdown hardening as Compose.
+
+## HTTP and UDP smoke
+
+Build the diagnostic once, then exercise the actual published HTTP and UDP
+paths. The test creates a public listing, sends authenticated presence and punch
+traffic through UDP 9050, establishes peer-to-peer traffic, reports the outcome,
+and deregisters cleanly:
+
+```bash
+dotnet build src/FinalFactory.Rendezvous.TestClient --configuration Release
+./scripts/smoke-deployment.sh
+```
+
+For the local Compose profile, the script derives a ten-minute diagnostic
+publisher credential from the ignored local key without printing either secret.
+For production, do not copy the signing key to the smoke host. Instead inject a
+short-lived, region-scoped credential through
+`RENDEZVOUS_PUBLISHER_CREDENTIAL`, and set the external endpoints:
+
+```bash
+export RENDEZVOUS_PUBLISHER_CREDENTIAL='<short-lived deployment credential>'
+export RENDEZVOUS_SMOKE_HTTP_URL='https://rendezvous.your-company.tld/'
+export RENDEZVOUS_SMOKE_UDP_ENDPOINT='rendezvous-udp.your-company.tld:9050'
+export RENDEZVOUS_SMOKE_GAME_ID='<credential game ID>'
+export RENDEZVOUS_SMOKE_ENVIRONMENT_ID='<credential environment ID>'
+export RENDEZVOUS_SMOKE_REGION='<credential region>'
+export RENDEZVOUS_SMOKE_PROTOCOL_VERSION='<enabled protocol version>'
+./scripts/smoke-deployment.sh
+```
+
+Those four scope values must match both the short-lived credential and an
+enabled server policy. The defaults (`space-game`, `smoke`, `local`, protocol
+`1`) are only for the checked-in local Compose profile.
+
+The smoke fails unless both health endpoints and the complete authenticated UDP
+mediation/direct-traffic flow succeed. It does not prove every consumer NAT;
+run the topology harness and representative external-network tests as well.
+
+## Restart, upgrade, rollback, and backup
+
+Rendezvous has no durable runtime database. Restarting intentionally loses all
+listings, observed endpoints, attempts, replay markers, and runtime-only
+revocations. Hosts must treat registration as a renewable lease and re-register
+after service recovery. Clients must re-browse and start a new bounded attempt.
+
+Back up only reviewed configuration, policy, secret references, key material and
+its custody/lifecycle records, deployment manifests, and image digest. Never
+claim a backup contains live sessions or endpoints. Restore keys only through the
+secret system, not into the image or repository.
+
+For an upgrade:
+
+1. Build and test the new pinned digest; validate configuration without starting
+   a second active instance.
+2. Drain and stop the current process, verify both sockets are released, then
+   start the replacement on the same public endpoints.
+3. Require live/readiness and HTTP+UDP smoke success; monitor host
+   re-registration, error rate, and direct-connect outcomes.
+
+For rollback, repeat the same stop-before-start sequence with the previously
+recorded image digest and compatible configuration/key set. Never run old and
+new versions concurrently to avoid split ephemeral state. If a wire-incompatible
+change ever becomes necessary, use a new API/protocol version rather than a
+rolling two-version replica set.

docs/evidence/capacity/v2/candidate-2cpu.json

@@ -0,0 +1,148 @@
+{
+  "schemaVersion": 2,
+  "evidenceVersion": "v2",
+  "generatedAt": "2026-07-16T14:10:53.6981858+00:00",
+  "profile": "candidate",
+  "runtime": {
+    "framework": ".NET 10.0.9",
+    "operatingSystem": "CachyOS",
+    "kernel": "Unix 7.1.3.2",
+    "architecture": "X64",
+    "cpuModel": "AMD Ryzen 7 9800X3D 8-Core Processor",
+    "processorCount": 2,
+    "cpuAffinity": "0,1",
+    "cpuQuota": "not-enforced",
+    "memoryLimit": "not-enforced",
+    "garbageCollector": "workstation",
+    "commitSha": "cf14836d48b0b4aaa67f99433f4fba3585bcd2bb",
+    "treeState": "clean",
+    "command": "RENDEZVOUS_CAPACITY_PROFILE=candidate RENDEZVOUS_CAPACITY_CPUSET=0,1 ./scripts/run-capacity-gate.sh",
+    "imageDigest": "not-containerized",
+    "workloadSeed": "fixed-sequences-random-identifiers",
+    "capacityPhaseAverageCpuPercent": 56.37724115383554,
+    "peakWorkingSetBytes": 169705472,
+    "managedBytesAfterCleanup": 35615200
+  },
+  "targets": {
+    "visibleListings": 25000,
+    "activeJoinAttempts": 10000,
+    "coreControlOperationsPerSecond": 200,
+    "coreMediationOperationsPerSecond": 2000,
+    "coreControlP95Milliseconds": 200,
+    "coreMediationP95Milliseconds": 100,
+    "maximumAverageCpuPercent": 70,
+    "maximumWorkingSetBytes": 1610612736,
+    "soakCycles": 1000,
+    "soakDurationSeconds": 300
+  },
+  "measurements": [
+    {
+      "operation": "registration-and-presence",
+      "samples": 1000,
+      "p50Milliseconds": 0.003,
+      "p95Milliseconds": 0.0046,
+      "p99Milliseconds": 0.0054,
+      "operationsPerSecond": 282453.96000451926,
+      "minimumOperationsPerSecond": 200,
+      "budgetMilliseconds": 200,
+      "passed": true
+    },
+    {
+      "operation": "lease-renewal",
+      "samples": 1000,
+      "p50Milliseconds": 0.0004,
+      "p95Milliseconds": 0.0009,
+      "p99Milliseconds": 0.0021,
+      "operationsPerSecond": 968992.2480620155,
+      "minimumOperationsPerSecond": 200,
+      "budgetMilliseconds": 200,
+      "passed": true
+    },
+    {
+      "operation": "visible-session-browse",
+      "samples": 250,
+      "p50Milliseconds": 0.9046,
+      "p95Milliseconds": 3.3704,
+      "p99Milliseconds": 3.9471,
+      "operationsPerSecond": 695.5799787597697,
+      "minimumOperationsPerSecond": 200,
+      "budgetMilliseconds": 200,
+      "passed": true
+    },
+    {
+      "operation": "join-attempt-issuance",
+      "samples": 1000,
+      "p50Milliseconds": 0.0029,
+      "p95Milliseconds": 0.0045,
+      "p99Milliseconds": 0.0055,
+      "operationsPerSecond": 296428.042092782,
+      "minimumOperationsPerSecond": 200,
+      "budgetMilliseconds": 200,
+      "passed": true
+    },
+    {
+      "operation": "simultaneous-punch-pairing",
+      "samples": 1000,
+      "p50Milliseconds": 0.0043,
+      "p95Milliseconds": 0.0073,
+      "p99Milliseconds": 0.0115,
+      "operationsPerSecond": 109212.03516627532,
+      "minimumOperationsPerSecond": 2000,
+      "budgetMilliseconds": 100,
+      "passed": true
+    },
+    {
+      "operation": "principal-revocation",
+      "samples": 50,
+      "p50Milliseconds": 0.518,
+      "p95Milliseconds": 0.7049,
+      "p99Milliseconds": 11.8557,
+      "operationsPerSecond": 1320.1773262184577,
+      "minimumOperationsPerSecond": 50,
+      "budgetMilliseconds": 200,
+      "passed": true
+    },
+    {
+      "operation": "telemetry-recording",
+      "samples": 1000,
+      "p50Milliseconds": 0.0001,
+      "p95Milliseconds": 0.0001,
+      "p99Milliseconds": 0.0001,
+      "operationsPerSecond": 1438641.9220256077,
+      "minimumOperationsPerSecond": 10000,
+      "budgetMilliseconds": 1,
+      "passed": true
+    },
+    {
+      "operation": "coincident-listing-attempt-expiry",
+      "samples": 1,
+      "p50Milliseconds": 29.6882,
+      "p95Milliseconds": 29.6882,
+      "p99Milliseconds": 29.6882,
+      "operationsPerSecond": 33.682962483916384,
+      "minimumOperationsPerSecond": 0,
+      "budgetMilliseconds": 200,
+      "passed": true
+    }
+  ],
+  "state": {
+    "peakListings": 25000,
+    "peakAttempts": 10000,
+    "peakReplayMarkers": 0,
+    "finalListings": 0,
+    "finalAttempts": 0,
+    "finalReplayMarkers": 0,
+    "expiryChurn": 94906,
+    "maintenanceSweeps": 36307,
+    "soakCyclesCompleted": 75126848,
+    "soakDurationSeconds": 300.0000015,
+    "soakPeakScheduledExpiryEntries": 7,
+    "soakManagedGrowthBytes": -257288,
+    "soakHandleGrowth": 2,
+    "restartStartedEmpty": true,
+    "overloadWasTyped": true,
+    "recoverySucceeded": true
+  },
+  "failures": [],
+  "passed": true
+}

docs/integration/test-client.md

@@ -0,0 +1,97 @@
+# Diagnostic TestClient integration guide
+
+Tracking: #25
+
+`FinalFactory.Rendezvous.TestClient` is the smallest supported public-SDK consumer.
+It exists for integration development, CI smoke checks, deployment verification,
+and operator diagnosis. It is intentionally not a production game client, game
+server, matchmaking UI, or relay.
+
+The automated scenario matrix, privileged Linux namespace run, and topology
+limitations are documented in the [deterministic topology harness](topology-harness.md).
+
+## Prerequisites
+
+Start a configured Rendezvous service and note both its HTTP base URL and UDP
+mediator endpoint. The host needs a tenant-scoped publisher credential from the
+deployment secret boundary. Put it in an environment variable and pass only that
+variable's name when the default is unsuitable:
+
+```bash
+export RENDEZVOUS_PUBLISHER_CREDENTIAL='<deployment-supplied value>'
+```
+
+Never put the credential in a command argument, URL, checked-in configuration,
+shell trace, or captured test fixture. The development server's signing material
+is process-ephemeral; credentials from a prior development process are invalid.
+
+## Manual three-terminal flow
+
+Start the host:
+
+```bash
+dotnet run --project src/FinalFactory.Rendezvous.TestClient -- \
+  host --service http://127.0.0.1:5000/ --mediator 127.0.0.1:9050 \
+  --game space-game --environment development --region local --protocol 1
+```
+
+Browse from another terminal:
+
+```bash
+dotnet run --project src/FinalFactory.Rendezvous.TestClient -- \
+  browse --service http://127.0.0.1:5000/ \
+  --game space-game --environment development --region local --protocol 1
+```
+
+Join from a third terminal. Omit `--listing` for an interactive choice:
+
+```bash
+dotnet run --project src/FinalFactory.Rendezvous.TestClient -- \
+  join --service http://127.0.0.1:5000/ --mediator 127.0.0.1:9050 \
+  --game space-game --environment development --region local --protocol 1 \
+  --listing 00000000-0000-0000-0000-000000000000
+```
+
+Replace the sample UUID with the public listing ID printed by host or browse.
+Host and join each create one caller-owned LiteNetLib manager. That same socket
+sends presence/punch traffic, establishes the authenticated direct connection,
+and carries the ping/echo/ack/completion payload. The final completion confirms
+that the host received the reliable acknowledgement; none of this traffic passes through the HTTP
+service or UDP mediator.
+
+## CI and deployment smoke flow
+
+Use `--script --json`, set `--listing` when deterministic selection matters, and
+check the documented process exit code. `--timeout-seconds` bounds each startup,
+traversal, or direct-traffic stage; a script host also uses it as its total runtime
+unless `--run-seconds` is explicit. A host can add `--exit-after-echo` so it
+terminates after the joining peer acknowledges direct traffic and receives the
+host's completion confirmation. Every wait is
+bounded by coordinator state and `--timeout-seconds`; no orchestration should use
+an unbounded sleep.
+
+The normal test suite contains a real process gate that starts the built Server,
+host TestClient, and join TestClient, waits for readiness and versioned events,
+and verifies direct traffic, cleanup, JSON shape, and secret canaries. Process
+trees are force-terminated in the test cleanup path if normal shutdown fails.
+
+Useful success events are:
+
+- `host.registered`, `host.ready`, `host.direct-traffic`, and `host.deregistered`;
+- `browse.completed` and `browse.session`; and
+- `join.connected`, `join.direct-traffic`, and `join.outcome-report`.
+
+Failure events preserve stable typed phases and outcomes. When a terminal outcome
+contains a configured dedicated endpoint, `join.fallback` reports `available`
+with endpoint type `dedicated`; no raw address is printed and no fallback is
+started implicitly.
+
+## What the proof does and does not establish
+
+The deterministic loopback test proves the complete service/host/client protocol,
+ticket admission, and peer-to-peer payload path. Loopback is not evidence that all
+consumer routers, carrier-grade NATs, symmetric NATs, firewalls, VPNs, IPv6 paths,
+or platform policies permit hole punching. Same-LAN, separated observed endpoints,
+network namespaces/containers, mediator restart, and adverse topology coverage
+belong to the topology harness tracked by #14. Production rollout still requires
+tests from representative networks and a game-owned fallback policy.

docs/integration/topology-harness.md

@@ -0,0 +1,91 @@
+# Deterministic topology harness
+
+Issue #14 is verified at three layers. The layers are deliberately separate so
+the always-on gate remains deterministic while privileged CI workers can add a
+stronger operating-system topology without overstating what local emulation
+proves about the public Internet.
+
+## Always-on public-process gate
+
+`TestClientProcessIntegrationTests` launches the built server and the same
+`FinalFactory.Rendezvous.TestClient` executable shipped to operators. Every
+child process uses `--script --json`, dynamic HTTP and UDP ports, bounded
+state-driven waits, and enforced process-tree cleanup.
+
+The suite proves:
+
+| Scenario | Required observation |
+| --- | --- |
+| Three-party happy path | register, presence-ready, browse, authorize, punch, authenticated LiteNetLib connection, direct ping/echo/ack/completion traffic, outcome report, disconnect, deregister |
+| Same-LAN candidate | the connected peer is reported as `loopback` or `private`, never inferred merely from an introduction callback |
+| Empty and missing selection | browse exits `11`; exact missing lookup exits `10` |
+| Wrong tenant/protocol | no listing is returned for an incompatible protocol; exact joins with either mismatch fail before `join.punch` |
+| Traversal timeout | an unreachable mediator produces typed `PunchTimedOut`, exits `12`, advertises the configured dedicated fallback, and never connects to it |
+| Caller cancellation | POSIX `SIGINT` exits `130`, deregisters the listing, and removes it from public lookup |
+| Abrupt host loss | the listing disappears after the presence window and before its lease expires; public exact lookup intentionally reports `NotFound` |
+| Bounded host without a peer | exits `13` and still deregisters |
+
+Captured output is parsed as the stable JSON v1 event schema. Publisher
+credentials and signing-key material are checked against all captured output.
+The direct traffic payload is handled only by the caller-owned host and client
+LiteNetLib managers; the HTTP service and mediator do not implement or observe
+the echo protocol.
+
+Run the always-on scenarios with:
+
+```bash
+dotnet test Rendezvous.slnx --configuration Release --no-build \
+  --filter FullyQualifiedName~TestClientProcessIntegrationTests
+```
+
+## Deterministic protocol and adverse-state gate
+
+The following real service-boundary tests cover conditions that a public CLI
+cannot safely manufacture by accepting raw capabilities or tickets:
+
+| Scenario | Test evidence |
+| --- | --- |
+| Same-NAT private candidates | `NatMediationProcessorTests.MatchedPeersReceiveOneIntroductionAndSameNatPrivateCandidates` |
+| Separate observed endpoints | `NatMediationProcessorTests.DifferentNatsAndInvalidLocalClaimsExposeOnlyObservedPublicEndpoints` |
+| One-time introduction and replay | `InMemoryEphemeralRendezvousStoreTests.AttemptCapabilitiesAndIntroductionAreOneTime` |
+| Direct ticket replay | `RendezvousCoordinatorIntegrationTests.CallerOwnedManagersCompleteAuthenticatedDirectConnectionAndRejectTicketReplay` |
+| Wrong tenant/protocol and stale presence | `InMemoryEphemeralRendezvousStoreTests.JoinRequiresExactScopeProtocolAndFreshHostPresence` |
+| Cancellation and late callbacks | `RendezvousCoordinatorBehaviorTests.CancellationCompletesExactlyOnceAndLateCallbacksCannotReopenTheAttempt` |
+| Mediator restart | both cases of `UdpMediatorServiceTests.NativeLiteNetLibRequestsIntroduceTheAuthorizedPair`; the restarted case rebinds the same UDP port and completes a native LiteNetLib introduction |
+
+These tests use fake monotonic clocks or state predicates where expiry and race
+ordering matter. They do not use fixed sleeps as proof of state.
+
+## Privileged Linux namespace gate
+
+When a Linux CI worker can create network namespaces, the workflow sets
+`RENDEZVOUS_RUN_NETNS_TESTS=1` and reruns
+`PrivilegedLinuxNatNamespacesCompleteDirectTrafficAcrossSeparateObservedEndpoints`.
+The test creates a temporary WAN bridge, an isolated service namespace, two NAT
+router namespaces, and isolated host/client LAN namespaces. Each NAT has its own
+inside subnet and WAN address. Linux forwarding plus per-router MASQUERADE rules
+force the service to observe separate translated endpoints; the public TestClient
+processes must then complete authenticated direct traffic through those mappings
+using the public candidate. Namespaces, rules, veth pairs, bridge, processes, and
+sockets are removed in bounded async-disposal paths. A cleanup failure fails the
+test.
+
+If `ip netns add`/`iptables` is unavailable or the worker lacks `CAP_NET_ADMIN`,
+CI records the limitation and keeps the always-on loopback suite as the required gate.
+To request the privileged run explicitly:
+
+```bash
+RENDEZVOUS_RUN_NETNS_TESTS=1 dotnet test Rendezvous.slnx \
+  --configuration Release --no-build \
+  --filter FullyQualifiedName~PrivilegedLinuxNatNamespacesCompleteDirectTrafficAcrossSeparateObservedEndpoints
+```
+
+## What this does not prove
+
+Loopback, MASQUERADE, and namespace routing cannot reproduce every consumer router,
+carrier-grade NAT, firewall, IPv6 transition mechanism, symmetric NAT mapping,
+or real-world packet-loss pattern. The separate-observed-endpoint processor
+test proves that untrusted private claims are excluded and public candidates are
+selected; it is not presented as universal Internet traversal proof. Real
+network canaries and measured production readiness remain the scope of issue
+#23.

docs/operations/capacity-and-resilience.md

@@ -0,0 +1,189 @@
+# Capacity, resilience, and availability gate
+
+Tracking: #18
+
+This gate turns the v1 budgets in ADR 0003 into a repeatable release decision.
+It does not turn Rendezvous into a horizontally scalable service: v1 remains one
+active process with bounded in-memory state. A second process may be a cold
+standby, but it must not accept traffic until the first process has stopped and
+released the public HTTP and UDP endpoints.
+
+## Launch envelope and approved core-state profile
+
+The approved core-state profile is one Linux process limited to 2 vCPU and
+2 GiB RAM. Public HTTP/UDP numbers are launch objectives that require the #23
+real-network canary before they become a supported service claim:
+
+| Dimension | Value | Evidence status |
+| --- | --- | --- |
+| Visible listings | 25,000 | Enforced and measured here |
+| Active join attempts | 10,000 | Enforced and measured here |
+| Core control path | 200 operations/second; p95 at most 200 ms | Measured here |
+| Core mediation path | 2,000 pairings/second; p95 at most 100 ms | Measured here |
+| Sustained HTTP demand | 200 requests/second | #23 launch objective; not yet a supported claim |
+| Sustained UDP demand | 2,000 datagrams/second | #23 launch objective; not yet a supported claim |
+| Public HTTP/UDP latency | p95 at most 200 ms / 100 ms | #23 launch objective; not yet a supported claim |
+| Capacity-phase average CPU / peak working memory | below 70% / below 1.5 GiB | Measured for the core candidate |
+| Valid in-profile monthly availability | 99.5%, excluding announced maintenance | Operational objective |
+| Process-ready RTO / host-visible recovery | 15 seconds / 90 seconds | 15 seconds automated; 90-second deployment drill required |
+
+The proposed public-network mix is 20% registration/update, 30% lease-critical
+renew/delete, 30% browse, and 20% join authorization for HTTP. The UDP mix is
+60% authenticated host-presence refresh, 30% attempt contributions, and 10%
+invalid or duplicate traffic that must be dropped early. A deployment may use a
+lower per-game profile, but must not claim a higher one without new versioned
+evidence.
+
+The capacity harness fills the complete state ceilings, then measures
+registration plus presence, renewal, a 100-item compatible browse, join
+issuance, simultaneous two-peer pairing, principal revocation, and telemetry.
+It applies 200/100 ms guardrails and minimum 200 control / 2,000 mediation
+operations per second to the core hot path. Those measurements deliberately
+exclude Kestrel, LiteNetLib, TLS, JSON, socket scheduling, and the documented
+mixed traffic shape. The #23 real-network canary must exercise those layers,
+rate-shape the mix, record errors and shedding, and meet the public objectives
+before launch; a core result is not a public-network latency or throughput claim.
+
+## Reproduce the evidence
+
+Every push runs the quick profile and the selected fault matrix:
+
+```bash
+./scripts/run-capacity-gate.sh
+```
+
+Run the production candidate on an otherwise idle Linux host and restrict the
+runtime to two logical CPUs. The default candidate includes a five-minute,
+high-intensity expiry soak; use 3,600 seconds for a release-candidate endurance
+run:
+
+```bash
+export RENDEZVOUS_CAPACITY_PROFILE=candidate
+export RENDEZVOUS_CAPACITY_CPUSET=0,1
+export RENDEZVOUS_CAPACITY_OUTPUT="$PWD/artifacts/capacity/candidate.json"
+./scripts/run-capacity-gate.sh
+
+# Release-candidate endurance override:
+dotnet run --project tests/FinalFactory.Rendezvous.Capacity \
+  --configuration Release --no-build -- \
+  --profile candidate --soak-seconds 3600 \
+  --output artifacts/capacity/candidate-endurance.json
+```
+
+The machine must have at least 2 GiB available to the process. For formal
+deployment evidence, run inside the same cgroup/container shape as production.
+The v2 JSON embeds the commit and tree state, command, image context, CPU model,
+kernel, affinity, cgroup quota/limit, collector mode, and workload seed. Supply
+`RENDEZVOUS_EVIDENCE_IMAGE_DIGEST` when running a release image. Do not compare
+results collected under a debugger,
+concurrent build, thermal throttling, or oversubscribed CI host.
+
+The checked-in baseline is
+[`candidate-2cpu.json`](../evidence/capacity/v2/candidate-2cpu.json). It was
+produced on .NET 10.0.9/Linux x64 with CPU affinity restricted to two logical
+CPUs. It filled 25,000 listings and 10,000 attempts, peaked at about 162 MiB,
+and cleared all active/retained state. The five-minute baseline supersedes any
+earlier local probe when its timestamp and target duration differ.
+
+## Soak and bounded-state interpretation
+
+Each soak cycle creates a listing, repeatedly renews its lease and refreshes
+presence, creates a join attempt, replay marker, and retained outcome, checks
+that scheduled expiry entries remain proportional to live keys, then advances
+the injected monotonic clock beyond all
+deadlines, and verifies that listings, attempts, replay, idempotency, and outcome
+state return to zero. The candidate also measures managed-memory and process
+handle deltas after full collection. Failure is any retained state, more than
+64 MiB retained managed memory, more than eight retained handles, a working set
+above 1.5 GiB, an untyped capacity result, or failure to admit work after expiry.
+
+This accelerated soak intentionally executes far more state lifecycle/cleanup
+events than wall-clock traffic would permit. It catches stale deadline-queue
+entries, cache growth, replay/idempotency retention, and cleanup cost. Because
+it does not open Kestrel/LiteNetLib connections, its process-handle delta is only
+a harness guard and is not evidence of transport stability by itself. The
+selected production-process gate adds a ten-second real HTTP/UDP transport soak,
+samples child-process handles and RSS, asserts bounded growth, then verifies a
+clean SIGTERM and socket release. #23 must extend that into the full rate-shaped
+multi-client canary while sampling queues, managed memory, and state
+cardinalities. A one-hour core override remains required before tagging a
+production release.
+
+## Fault and recovery matrix
+
+`run-capacity-gate.sh` runs these deterministic production paths before the
+numeric profile:
+
+| Fault | Required result |
+| --- | --- |
+| HTTP/UDP overload and tracker exhaustion | Typed HTTP `429`/`CapacityExceeded`, silent UDP drop, bounded tracker keys, recovery after the window |
+| Optional traffic saturation | Lease-critical renew/update/delete capacity remains available |
+| Store/dependency unavailable | Readiness fails; new authorization returns typed `ServiceUnavailable`; liveness remains independent |
+| Graceful drain/SIGTERM | New work returns `Draining`; existing pairing may finish; process exits 0 and releases TCP/UDP before the deadline |
+| Hard restart | In-flight state is lost; SDK reports typed `ServiceUnavailable`; a host re-registers, rebinds presence, and becomes the only browser-visible replacement |
+| UDP listener bind/restart | Readiness stays false without the required listener; rebinding the advertised port restores native LiteNetLib pairing |
+| Wall-clock jump/skew | Monotonic lease/attempt authority is neither shortened nor extended; credential skew remains capped at 30 seconds |
+| Signing-secret rotation | New key signs, overlap verifies, retired/revoked key rejects, missing material fails startup |
+| Principal revocation | Listing, presence, attempts, and outcome paths are removed atomically within the latency budget |
+
+No external database exists in v1, so “dependency/store failure” means the
+process-local atomic store is marked unavailable or a required listener/key is
+unready. The service fails closed rather than pretending a degraded writable
+mode exists.
+
+## Bandwidth and amplification
+
+- Accepted application datagrams are at most 1,200 bytes.
+- Malformed, oversized, unauthenticated, stale, replayed, wrong-role, and
+  rate-limited traffic receives zero response bytes.
+- A completing authenticated contribution produces at most one introduction to
+  each observed peer, and the combined response is at most 2.0 times that
+  contribution's bytes.
+- The frozen-envelope and native LiteNetLib socket tests measure this on the real
+  UDP listener; the hostile corpus and allocation gate exercise 10,000+ inputs
+  without input-sized logs, tasks, or queues.
+
+Bandwidth planning must therefore reserve ingress for the configured 2,000
+datagrams/second plus edge overhead and egress for a worst-case verified 2.0
+amplification. Actual successful pairs normally use two contributions and two
+introductions; normal gameplay leaves Rendezvous entirely.
+
+## Availability decision
+
+Single-active remains the v1 topology. The measured core profile proves bounded
+state and substantial core-path headroom, while public launch capacity remains
+conditional on #23. The service has a bounded stop-before-start restart path.
+Its failure domain is deliberately
+one process/node/public UDP endpoint: node, kernel, host network, DNS/TLS edge,
+secret configuration, or operator error can remove all readiness until the cold
+replacement owns the same source-preserving endpoint.
+
+The 99.5% objective permits about 216 minutes of unannounced downtime in a
+30-day month. Operations must target process readiness within 15 seconds and
+host-visible re-registration within 90 seconds, page when no ready instance
+exists, and include detection plus recovery in the monthly budget. The current
+in-process test validates typed downtime, same-port HTTP restart, fresh
+registration, presence rebinding, and browser visibility in under five seconds;
+the production-process test separately validates graceful termination, TCP/UDP
+release, replacement startup on the same endpoints, UDP readiness, and the
+15-second process-ready RTO. Cold-standby activation policy and the 90-second
+operator-to-host recovery objective still require a deployment drill before
+release. Rollout and rollback use the
+deployment runbook's drain, stop, socket-release, start, smoke sequence; never
+overlap old and new active processes.
+
+Bring shared TTL/CAS state and deterministic mediator routing forward before
+enabling two active instances if any of these occurs:
+
+- one node cannot sustain 150% of the measured 30-day peak while meeting SLOs;
+- CPU stays above 70%, memory above 75%, attempt depth above 70%, or limiter
+  drops/latency remain elevated after abusive traffic is excluded;
+- the availability target rises above 99.5% or planned maintenance must preserve
+  listings; or
+- one region requires multiple simultaneously active mediator endpoints.
+
+Rendezvous makes no multi-instance claim today, so a two-node atomic-pairing
+test is intentionally not applicable. It becomes a hard release gate with the
+shared-state/routing implementation; until then `SingleActiveInstance=false`
+fails production startup. Multi-region and relay remain separate evidence-driven
+decisions.

docs/operations/observability-and-operator-runbook.md

@@ -0,0 +1,144 @@
+# Observability and operator runbook
+
+This runbook defines the production signals and privileged controls for the
+Rendezvous service. The service emits `System.Diagnostics.Metrics` instruments
+from the `FinalFactory.Rendezvous` meter and distributed-tracing activities from
+`FinalFactory.Rendezvous.Server`. Connect those sources to the deployment's
+OpenTelemetry or equivalent collector. Do not add identifiers to metric labels.
+
+## Health and readiness
+
+- `GET /health/live` proves that the HTTP process can answer. It deliberately
+  remains independent of provisioning, the state store, drain state, and optional
+  listeners so an orchestrator does not restart a recoverable dependency failure.
+- `GET /health/ready` returns success only after the HTTP path is answering, the
+  required IPv4 UDP socket is bound, any configured IPv6 UDP socket is bound,
+  provisioning loaded successfully, the store is available, and drain has not
+  started. A failed check returns `503` and removes the instance from new work.
+- A graceful drain immediately makes readiness fail while liveness remains healthy.
+  Existing work may complete until the bounded store drain deadline.
+
+## Metrics and traces
+
+| Instrument | Purpose | Bounded dimensions |
+| --- | --- | --- |
+| `rendezvous.http.requests` / `rendezvous.http.duration` | HTTP volume and latency | operation, status code |
+| `rendezvous.udp.results` / `rendezvous.udp.duration` | UDP mediation volume and processing latency | frozen/litenet operation, result |
+| `rendezvous.limiter.drops` | Requests shed by admission controls | transport, fixed partition class |
+| `rendezvous.operator.authentication` | Accepted, forbidden, and rejected operator authentication | result |
+| `rendezvous.audit.events` | Privileged action outcomes | fixed action, result |
+| `rendezvous.connection.outcomes` | Client-reported direct-connect outcomes | normalized outcome, elapsed bucket |
+| `rendezvous.pairing.latency` | Time from attempt creation to successful peer introduction | none |
+| `rendezvous.queue.depth` | Active join-attempt queue depth | none |
+| `rendezvous.store.active_listings` / `active_leases` / `active_attempts` / `replay_markers` | Current ephemeral load | none |
+| `rendezvous.store.expiry_churn` | Cumulative natural expiry activity | none |
+| `rendezvous.store.available` | Store health (`1` available, `0` unavailable) | none |
+
+HTTP responses include `X-Rendezvous-Correlation-ID`. It is a generated trace ID
+or random value, never a caller-supplied session or player identifier. UDP and
+HTTP activities contain operation-level data only. Logs and traces must not add
+tokens, capabilities, session/listing IDs, player subjects, metadata, raw IP
+addresses, or endpoint values.
+
+Recommended dashboard panels are request rate and p50/p95/p99 latency by fixed
+operation, UDP result ratio, direct connection success ratio, pairing latency,
+active listings/attempts, expiry churn, limiter drops, store availability,
+operator authentication results, audit action results, and signing-key windows.
+
+## Alerts
+
+Tune thresholds from the normal production baseline, then keep these conditions
+as distinct actionable alerts:
+
+- **Signing key expiry:** page when any required signing key has less than seven
+  days before `signUntil`; escalate at 24 hours. Confirm a replacement is signing
+  and the previous key remains verify-only for the maximum credential lifetime.
+- **Authentication spike:** warn when rejected or forbidden operator authentication
+  exceeds five attempts in five minutes. Treat unexpected publisher-authentication
+  growth as a possible credential or integration incident.
+- **Direct success regression:** warn when the connected outcome ratio falls more
+  than 20% below its seven-day same-region baseline for 15 minutes, with a minimum
+  sample floor. Break down only by bounded outcome and time bucket.
+- **Saturation:** warn when queue depth remains above 70% of the configured attempt
+  limit, limiter drops are sustained, or p95 latency exceeds the service objective;
+  page at 90% or when lease-critical traffic is shed.
+- **Store degradation:** page immediately when `rendezvous.store.available` is zero
+  or readiness fails for the store. Rising expiry churn without corresponding new
+  work is a warning for stalled clients or clock/configuration mistakes.
+- **Listener/config readiness:** page when no ready instances remain. Investigate
+  UDP bind failures, a configured-but-unbound IPv6 listener, provisioning errors,
+  and unintended drain state separately.
+
+## Operator authentication and controls
+
+Operator credentials use a signing key configured with `CredentialKinds:
+["Operator"]`. Operator keys cannot be scoped to a game/environment or used for
+publisher credentials. Mint short-lived operator credentials through the trusted
+provisioning process, outside the public Rendezvous HTTP service, and grant only
+the required permission. Never place credentials in command history, URLs, logs,
+or support tickets.
+
+The application also enforces a default-deny source boundary. Configure at most
+32 exact operator source IPs in
+`Rendezvous:AbuseProtection:OperatorAllowedAddresses`; an empty list disables all
+operator HTTP access. Development permits loopback only. Production must place
+`/v1/operator/*` behind a private management listener or reverse-proxy ACL, list
+only the resulting trusted management source addresses, and block that path on
+the public edge. If forwarded headers are enabled, keep the existing exact-proxy,
+single-hop trust policy and allowlist the post-forwarding operator source. Verify
+from both an allowed management host and a denied public host before deployment.
+Denied sources are charged to the bounded general HTTP partition before credential
+or request-body processing, then receive `404`; sustained denied traffic receives
+the same typed `429` overload response as other public traffic.
+
+Operator traffic has a dedicated, bounded rate/concurrency partition and critical
+tracker-key reserve. Public browse/join saturation therefore cannot consume the
+operator control budget, while compromised management sources remain rate-limited.
+
+The OpenAPI document defines the separate `OperatorBearer` scheme. All endpoints
+are under `/v1/operator`:
+
+| Endpoint | Permission | Confirmation |
+| --- | --- | --- |
+| `GET /status` | `ReadPolicy` | none; returns aggregates, tenant status, safe key status, and audit counts |
+| `POST /listings/revoke` | `RevokePublisher` | repeat the exact listing ID in `confirmListingId` |
+| `POST /principals/revoke` | `RevokePublisher` | repeat the exact subject and choose a 1-600 second revocation lifetime |
+| `POST /keys/revoke` | `RotateKeys` | repeat the exact key ID; runtime revocation is immediate |
+| `POST /drain` | `ManagePolicy` | send the exact value `DRAIN` |
+
+Publisher credentials are rejected on this surface even if their subject resembles
+an operator. Destructive responses do not echo identifiers. The status response
+does not expose player identities, raw endpoints, session metadata, capabilities,
+or tokens. Every authenticated operator action, rejected confirmation, and
+permission denial is audited with actor and target fingerprints.
+
+Key revocation is process-local in the current single-instance store. Apply the
+same revocation to every instance, then replace configuration before restarting;
+a restart reconstructs the configured key ring. Principal revocation is bounded
+to ten minutes and removes that principal's active listings and attempts. A
+repeat action may extend an active revocation but never shortens it; wait for its
+original deadline rather than treating a shorter repeat as an un-revoke. Use
+listing revocation for one targeted session and drain before planned shutdown.
+
+## Audit retention and incident handling
+
+The in-process audit trail defaults to 10,000 entries and 30 days. It evicts the
+oldest record at capacity and purges expired records on the next write. Configure
+`Rendezvous:Audit:MaxEntries` and `RetentionDays` within their validated bounds.
+Export the structured `AuditTrail` log events through the deployment's protected
+logging pipeline when durable retention is required; the in-memory trail is not a
+durable compliance archive. Those events include only timestamps, fixed action
+fields, correlation IDs, and actor/target fingerprints.
+
+Audit records retain timestamp, fixed action/result, target kind, correlation ID,
+and 96-bit SHA-256 fingerprints of actor and target. Routine logs contain only the
+fixed action/result/target kind and correlation ID. Restrict audit access to the
+operator role, retain aggregates only as long as operationally necessary, and
+delete raw exported audit data according to the 30-day policy unless an incident
+hold is approved.
+
+During an incident: confirm readiness and store health; capture aggregate graphs
+and correlation IDs; revoke the narrowest listing, principal, or key; drain only
+when isolation is required; record the action in the incident timeline; and verify
+that direct success, limiter drops, and authentication rates return to baseline.
+Do not copy player data, endpoints, or credentials into the incident record.

docs/security/abuse-protection.md

@@ -0,0 +1,103 @@
+# Hostile-input and overload protection
+
+Tracking: #15
+
+Rendezvous treats every public HTTP request and UDP datagram as hostile. The
+server applies bounded fixed-window request budgets and concurrency ceilings in
+two stages so malformed input is discarded before expensive work while valid
+traffic is also isolated by its authenticated scope.
+
+## Enforcement order
+
+1. Kestrel and the HTTP abuse middleware cap request bodies at 16 KiB. A known
+   oversized body receives a typed `413` response before endpoint dispatch.
+2. Every HTTP request consumes global, source-prefix, and operation budgets and
+   acquires the corresponding concurrency leases. IPv4 sources share a `/24`
+   budget and IPv6 sources share a `/56` budget; raw addresses are not retained.
+   Non-lease operations also consume a smaller optional-work budget, leaving a
+   configured global and source-prefix reserve for renew, update, and delete
+   operations during shedding.
+   Health probes use their own source-prefix budget so public API overload cannot
+   make a healthy instance fail its orchestrator probes, while health traffic is
+   still bounded.
+   Operator endpoints likewise use a separate bounded rate/concurrency partition
+   backed by the critical tracker reserve. They first require an exact source IP
+   from the default-deny `OperatorAllowedAddresses` policy, so public traffic
+   cannot spend the incident-response budget.
+3. Once an endpoint has safely derived identities, it also acquires applicable
+   tenant, principal or capability, and listing/attempt budgets. Secret
+   capabilities are represented only by bounded SHA-256 fingerprints.
+4. Every UDP envelope consumes global, source-prefix, and wire-operation
+   budgets before decoding. A structurally and cryptographically valid request
+   then consumes capability, role, and mediation-handle budgets before state
+   mutation or introduction.
+5. HTTP overload returns the stable `RateLimited` error, status `429`, and a
+   bounded `Retry-After` value in both the header and response contract. UDP
+   overload and every invalid UDP input are silently dropped.
+
+The same HTTP identity budget is computed whether or not a listing or attempt
+exists. Rejection therefore does not disclose resource existence. Publisher
+authentication also completes before any tenant/resource operation, while the
+pre-authentication source budget prevents invalid credentials from bypassing
+load shedding.
+
+## Bounded state and recovery
+
+`Rendezvous:AbuseProtection:MaxTrackedKeys` is a hard combined ceiling for rate
+and active-concurrency keys. General HTTP and UDP traffic cannot consume the
+configured `CriticalTrackedKeyReserve`; lease operations, health probes, and
+allowlisted operator controls may
+use that reserve but never exceed the hard ceiling. A request that would exceed
+its applicable ceiling fails closed without adding state. Fixed-window rate keys
+are cleared at the next window boundary; concurrency keys are removed as their
+request leases finish. HTTP and UDP trackers have separate locks and cardinality
+partitions, so a UDP flood cannot block HTTP admission on a shared lock or
+consume HTTP key capacity. This gives
+deterministic burst recovery and prevents an attacker from growing a permanent
+high-cardinality address, credential, or resource table.
+
+The complete default profile is checked into
+`src/FinalFactory.Rendezvous.Server/appsettings.json`. Operators may lower or
+tune limits for a measured deployment profile, but must preserve all dimensions
+and leave the tracker ceiling above the maximum simultaneous key set. A rolling
+deployment should use the same profile on every instance. These per-process
+limits are a final service boundary; an edge proxy may add stricter distributed
+limits but is not a substitute for them.
+
+When an HTTP reverse proxy is used, every immediate proxy address must be
+allowlisted in `Rendezvous:AbuseProtection:TrustedProxyAddresses` (or indexed
+environment variables such as
+`Rendezvous__AbuseProtection__TrustedProxyAddresses__0`). Only one forwarded
+hop is accepted. With an empty allowlist, forwarded headers are ignored and the
+direct TCP peer is the source. Never add a broad network range or accept
+untrusted `X-Forwarded-For` input: that would let a caller choose its own rate
+partition.
+
+## Reflection, disclosure, and logging rules
+
+- UDP sends nothing for malformed, oversized, unauthenticated, stale,
+  replayed, wrong-role, or rate-limited input.
+- Introductions are emitted only after both role-scoped capabilities bind to
+  their observed gameplay-socket sources. HTTP never supplies a public
+  introduction target.
+- Private candidates must be same-family private unicast addresses and are used
+  only for peers observed behind the same public address.
+- Abuse keys, exceptions, and responses never include bearer credentials,
+  capabilities, tickets, raw endpoints, metadata values, or hostile markup.
+- Endpoint and capability values are not used as metric labels or log fields.
+
+## Verification
+
+The deterministic test corpora use the recorded seeds `0x152026`, `0x154A50`,
+and `0x1557A7E`. They exercise 10,000 arbitrary UDP envelopes through the
+production decoder, 5,000 arbitrary HTTP/credential parser inputs, and 1,000
+mutated state transitions, including the oversized and configured-capacity
+boundaries.
+Focused tests cover IPv4 and IPv6 prefix
+partitioning, tenant/principal/resource concurrency, tracker exhaustion,
+window recovery, wire-operation isolation, a steady-state allocation ceiling,
+typed `429`/`413` responses, secret fingerprint redaction, and silent
+authenticated UDP shedding. The existing state, contract, HTTP, client,
+and mediator suites continue to cover cross-tenant access, replay, role swaps,
+credential rotation, bounded metadata, endpoint validation, and one-shot
+amplification behavior.

docs/security/control-matrix.md

@@ -11,7 +11,7 @@ backlog where the control is implemented and verified.
 | Per-game credentials and signing keys | Provisioned principals and versioned keys are scoped to game/environment; secrets come from a provider and never a public binary. (#5) | Cross-tenant authorization tests, rotation/overlap/revocation tests, and secret scans. |
 | Short-lived, single-purpose tokens resistant to replay | Issuer fixes audience, tenant, attempt, role, issued/expiry times, nonce, and key ID; store atomically consumes nonce/ticket. (#4, #6, #10) | Golden vectors; expired, future, mutated, wrong-role, wrong-tenant, and concurrent replay tests. |
 | Strict payload, metadata, and token size limits | ADR 0003 ceilings are checked before allocation/deserialization and again at domain construction. (#4, #15) | Boundary/property tests, malformed corpus, and allocation-aware fuzzing. |
-| Registration, query, and introduction rate limits | Layered per-address, principal, tenant, and global token buckets with bounded queues and stable retry guidance. (#15) | Limit partition/isolation tests and overload/soak profiles. |
+| Registration, query, and introduction rate limits | Layered fixed-window budgets and concurrency leases cover global, operation, IPv4 `/24` or IPv6 `/56`, tenant, principal/capability, and listing/attempt dimensions with a bounded key table and stable retry guidance. (#15) | Deterministic partition, concurrency, tracker-exhaustion, recovery, typed-overload, and silent-UDP-shedding tests. |
 | Lease expiry removes abandoned servers | Visibility and join eligibility atomically require a fresh lease and fresh authenticated presence. (#6, #7) | Fake-clock expiry, renew/expire race, restart, and stale-host join tests. |
 | Validate game, environment, room, and protocol boundaries | Every identifier is a validated type; store keys and authorization decisions include server-derived tenant scope; protocol is exact-match in v1. (#4-#10) | Contract, tenant-isolation, incompatible-version, and confused-deputy tests. |
 | Structured audit events without secrets or reusable credentials | Allowlisted audit schema excludes metadata values, raw endpoints, tokens, and key material; event volume is bounded. (#16) | Captured-log/audit assertions and credential canary scans. |

docs/security/provisioning.md

@@ -63,8 +63,9 @@ only its public key ID/lifecycle metadata and does not require retired secret
 material to remain available.
 
 Key IDs are non-secret base64url identifiers. Secret references are resolved
-through `ISecretProvider`; production supports `env:<VARIABLE>` references and
-the interface is replaceable by a deployment-specific vault/KMS adapter. The
+through `ISecretProvider`; production supports base64 `env:<VARIABLE>` and raw
+`file:/absolute/path` references to bounded non-symlink files. The interface is
+replaceable by a deployment-specific vault/KMS adapter. The
 committed development profile uses an in-memory random key identified by a
 `development:ephemeral/...` reference. It never writes key material to disk and
 all credentials become invalid when the process exits.
@@ -74,8 +75,10 @@ all credentials become invalid when the process exits.
 `Rendezvous:Provisioning` supplies issuer, audience, clock skew, signing-key
 descriptors, and game policies. A production key reference such as
 `env:RENDEZVOUS_SIGNING_KEY_2026_01` expects that environment variable to hold at
-least 32 random bytes encoded as base64. Missing, malformed, short, inactive, or
-duplicate keys stop startup with a key-ID-only diagnostic. No game-wide secret
+least 32 random bytes encoded as base64. `file:/run/secrets/rendezvous-signing`
+expects the raw bytes in a read-only, absolute, non-symlink file. Missing,
+malformed, short, inactive, or duplicate keys stop startup with a key-ID-only
+diagnostic. No game-wide secret
 belongs in `appsettings`, source control, examples, the Client package, URLs,
 responses, logs, metrics, exceptions, or diagnostic dumps.
 

scripts/run-capacity-gate.sh

@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+PROFILE="${RENDEZVOUS_CAPACITY_PROFILE:-quick}"
+OUTPUT="${RENDEZVOUS_CAPACITY_OUTPUT:-$ROOT/artifacts/capacity/rendezvous-capacity-v2.json}"
+CPUSET="${RENDEZVOUS_CAPACITY_CPUSET:-}"
+PROJECT="$ROOT/tests/FinalFactory.Rendezvous.Capacity/FinalFactory.Rendezvous.Capacity.csproj"
+TESTS="$ROOT/tests/FinalFactory.Rendezvous.Tests/FinalFactory.Rendezvous.Tests.csproj"
+
+if [[ "$PROFILE" != quick && "$PROFILE" != candidate ]]; then
+    printf 'RENDEZVOUS_CAPACITY_PROFILE must be quick or candidate.\n' >&2
+    exit 2
+fi
+command -v dotnet >/dev/null || {
+    printf 'Missing required command: dotnet\n' >&2
+    exit 2
+}
+if [[ -n "$CPUSET" ]]; then
+    command -v taskset >/dev/null || {
+        printf 'taskset is required when RENDEZVOUS_CAPACITY_CPUSET is set.\n' >&2
+        exit 2
+    }
+fi
+
+cd "$ROOT"
+export RENDEZVOUS_EVIDENCE_COMMIT="$(git rev-parse HEAD)"
+if [[ -n "$(git status --porcelain)" ]]; then
+    export RENDEZVOUS_EVIDENCE_TREE_STATE=dirty
+else
+    export RENDEZVOUS_EVIDENCE_TREE_STATE=clean
+fi
+if [[ "$PROFILE" == candidate && "$RENDEZVOUS_EVIDENCE_TREE_STATE" != clean ]]; then
+    printf 'Candidate evidence requires a clean source tree.\n' >&2
+    exit 2
+fi
+export RENDEZVOUS_EVIDENCE_CPUSET="${CPUSET:-unrestricted}"
+export RENDEZVOUS_EVIDENCE_COMMAND="RENDEZVOUS_CAPACITY_PROFILE=$PROFILE RENDEZVOUS_CAPACITY_CPUSET=${CPUSET:-unrestricted} ./scripts/run-capacity-gate.sh"
+
+dotnet restore "$ROOT/Rendezvous.slnx" --locked-mode
+dotnet build "$ROOT/Rendezvous.slnx" --configuration Release --no-restore
+
+filter='FullyQualifiedName~TrackerCapacityFailsClosedWithoutGrowingAndAWindowResetRecovers|FullyQualifiedName~OptionalTrafficCannotConsumeTheLeaseOperationReserve|FullyQualifiedName~ConcurrentAbusiveBurstStaysBoundedAndCannotBlockCriticalHttp|FullyQualifiedName~HttpOverloadIsTypedAndOversizedBodiesAreRejectedBeforeDispatch|FullyQualifiedName~WallClockMovementDoesNotExpireOrExtendLease|FullyQualifiedName~RepeatedMutableDeadlineRefreshesKeepOneScheduledEntryPerKey|FullyQualifiedName~RepeatedPrincipalRevocationCanExtendButCannotShortenProtection|FullyQualifiedName~RestartHasNewGenerationAndNoEphemeralState|FullyQualifiedName~RestartReturnsTypedUnavailabilityThenAllowsHostReregistration|FullyQualifiedName~DrainRejectsNewWorkAllowsInflightCompletionThenClearsState|FullyQualifiedName~UnavailableStoreFailsNewAuthorizationClosedAndErasesActiveState|FullyQualifiedName~KeyRotationHonorsOverlapAndRejectsRetiredKeys|FullyQualifiedName~OperatorSurfaceSeparatesAuthenticationConfirmsActionsAndRedactsInspection|FullyQualifiedName~SigtermDrainsThenReleasesHttpAndUdpSockets|FullyQualifiedName~ProductionTransportSoakKeepsHandlesMemoryAndSocketsBounded|FullyQualifiedName~NativeLiteNetLibRequestsIntroduceTheAuthorizedPair'
+dotnet test "$TESTS" --configuration Release --no-build --filter "$filter" \
+    --logger 'console;verbosity=minimal'
+
+mkdir -p "$(dirname "$OUTPUT")"
+arguments=(
+    dotnet run --project "$PROJECT" --configuration Release --no-build --
+    --profile "$PROFILE" --output "$OUTPUT"
+)
+if [[ -n "$CPUSET" ]]; then
+    taskset -c "$CPUSET" "${arguments[@]}"
+else
+    "${arguments[@]}"
+fi
+
+printf 'Capacity and resilience gate passed; evidence: %s\n' "$OUTPUT"

scripts/smoke-deployment.sh

@@ -0,0 +1,148 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+SERVICE_URL="${RENDEZVOUS_SMOKE_HTTP_URL:-http://127.0.0.1:8080/}"
+MEDIATOR="${RENDEZVOUS_SMOKE_UDP_ENDPOINT:-127.0.0.1:9050}"
+TIMEOUT_SECONDS="${RENDEZVOUS_SMOKE_TIMEOUT_SECONDS:-30}"
+LOCAL_KEY="${RENDEZVOUS_SMOKE_LOCAL_KEY:-$ROOT/deploy/compose/secrets/signing-key}"
+PROJECT="$ROOT/src/FinalFactory.Rendezvous.TestClient/FinalFactory.Rendezvous.TestClient.csproj"
+BUILD_CONFIGURATION="${RENDEZVOUS_SMOKE_CONFIGURATION:-Release}"
+GAME_ID="${RENDEZVOUS_SMOKE_GAME_ID:-space-game}"
+ENVIRONMENT_ID="${RENDEZVOUS_SMOKE_ENVIRONMENT_ID:-smoke}"
+REGION="${RENDEZVOUS_SMOKE_REGION:-local}"
+PROTOCOL_VERSION="${RENDEZVOUS_SMOKE_PROTOCOL_VERSION:-1}"
+
+for command in curl date dotnet jq mktemp od openssl tail tr wc; do
+    command -v "$command" >/dev/null || {
+        printf 'Missing required command: %s\n' "$command" >&2
+        exit 2
+    }
+done
+
+if [[ ! "$TIMEOUT_SECONDS" =~ ^[0-9]+$ ]] || (( TIMEOUT_SECONDS < 1 || TIMEOUT_SECONDS > 300 )); then
+    printf 'RENDEZVOUS_SMOKE_TIMEOUT_SECONDS must be an integer from 1 through 300.\n' >&2
+    exit 2
+fi
+if [[ ! "$PROTOCOL_VERSION" =~ ^[0-9]+$ ]] || (( PROTOCOL_VERSION < 1 )); then
+    printf 'RENDEZVOUS_SMOKE_PROTOCOL_VERSION must be a positive integer.\n' >&2
+    exit 2
+fi
+for scoped_value in "$GAME_ID" "$ENVIRONMENT_ID" "$REGION"; do
+    if [[ -z "$scoped_value" ]]; then
+        printf 'Smoke game, environment, and region values must not be empty.\n' >&2
+        exit 2
+    fi
+done
+
+base64url() {
+    openssl base64 -A | tr '+/' '-_' | tr -d '='
+}
+
+local_credential() {
+    if [[ ! -f "$LOCAL_KEY" ]] || [[ "$(wc -c < "$LOCAL_KEY")" -ne 32 ]]; then
+        printf 'Local Compose smoke key must be exactly 32 bytes: %s\n' "$LOCAL_KEY" >&2
+        exit 2
+    fi
+
+    local now expires nonce payload encoded signed hex signature
+    now="$(date +%s)"
+    expires="$((now + 600))"
+    nonce="$(openssl rand -hex 16)"
+    payload="$(jq -cn \
+        --arg issuer final-factory-rendezvous-smoke \
+        --arg audience rendezvous-service \
+        --arg subject local-smoke-host \
+        --arg kind dedicatedPublisher \
+        --arg gameId "$GAME_ID" \
+        --arg environmentId "$ENVIRONMENT_ID" \
+        --arg region "$REGION" \
+        --arg nonce "$nonce" \
+        --argjson now "$now" \
+        --argjson expires "$expires" \
+        '{version:1,issuer:$issuer,audience:$audience,subject:$subject,kind:$kind,gameId:$gameId,environmentId:$environmentId,regions:[$region],permissions:[],issuedAtUnixSeconds:$now,notBeforeUnixSeconds:$now,expiresAtUnixSeconds:$expires,nonce:$nonce}')"
+    encoded="$(printf '%s' "$payload" | base64url)"
+    signed="rv1.local-smoke-1.$encoded"
+    hex="$(od -An -v -tx1 "$LOCAL_KEY" | tr -d ' \n')"
+    signature="$(printf '%s' "$signed" \
+        | openssl dgst -sha256 -mac HMAC -macopt "hexkey:$hex" -binary \
+        | base64url)"
+    printf '%s.%s' "$signed" "$signature"
+}
+
+credential="${RENDEZVOUS_PUBLISHER_CREDENTIAL:-}"
+if [[ -z "$credential" ]]; then
+    credential="$(local_credential)"
+fi
+export RENDEZVOUS_PUBLISHER_CREDENTIAL="$credential"
+
+curl --fail --silent --show-error --max-time 5 "${SERVICE_URL%/}/health/live" >/dev/null
+curl --fail --silent --show-error --max-time 5 "${SERVICE_URL%/}/health/ready" >/dev/null
+
+temp_dir="$(mktemp -d)"
+host_log="$temp_dir/host.jsonl"
+join_log="$temp_dir/join.jsonl"
+host_pid=''
+cleanup() {
+    local status="$?"
+    if [[ -n "$host_pid" ]] && kill -0 "$host_pid" 2>/dev/null; then
+        kill -TERM "$host_pid" 2>/dev/null || true
+        wait "$host_pid" 2>/dev/null || true
+    fi
+    if [[ "$status" -ne 0 ]]; then
+        printf 'Deployment smoke failed; sanitized diagnostic events follow.\n' >&2
+        [[ -f "$host_log" ]] && jq -c . "$host_log" >&2 || true
+        [[ -f "$join_log" ]] && jq -c . "$join_log" >&2 || true
+    fi
+    rm -rf "$temp_dir"
+    return "$status"
+}
+trap cleanup EXIT
+trap 'exit 130' INT
+trap 'exit 143' TERM
+
+dotnet run --project "$PROJECT" --configuration "$BUILD_CONFIGURATION" --no-build -- \
+    host --service "$SERVICE_URL" --mediator "$MEDIATOR" \
+    --game "$GAME_ID" --environment "$ENVIRONMENT_ID" --region "$REGION" --protocol "$PROTOCOL_VERSION" \
+    --script --json --exit-after-echo --timeout-seconds "$TIMEOUT_SECONDS" \
+    >"$host_log" 2>&1 &
+host_pid="$!"
+
+ready=false
+for ((iteration = 0; iteration < TIMEOUT_SECONDS * 4; iteration++)); do
+    if jq -e 'select(.event == "host.ready")' "$host_log" >/dev/null 2>&1; then
+        ready=true
+        break
+    fi
+    if ! kill -0 "$host_pid" 2>/dev/null; then
+        printf 'Host diagnostic stopped before it became ready.\n' >&2
+        jq -c . "$host_log" >&2 || true
+        exit 1
+    fi
+    sleep 0.25
+done
+if [[ "$ready" != true ]]; then
+    printf 'Host diagnostic did not become ready within %s seconds.\n' "$TIMEOUT_SECONDS" >&2
+    exit 1
+fi
+
+listing_id="$(jq -r 'select(.event == "host.registered") | .listingId' "$host_log" | tail -n 1)"
+if [[ -z "$listing_id" || "$listing_id" == null ]]; then
+    printf 'Host diagnostic did not report a listing ID.\n' >&2
+    exit 1
+fi
+
+dotnet run --project "$PROJECT" --configuration "$BUILD_CONFIGURATION" --no-build -- \
+    join --service "$SERVICE_URL" --mediator "$MEDIATOR" \
+    --game "$GAME_ID" --environment "$ENVIRONMENT_ID" --region "$REGION" --protocol "$PROTOCOL_VERSION" \
+    --listing "$listing_id" --script --json --timeout-seconds "$TIMEOUT_SECONDS" \
+    >"$join_log" 2>&1
+wait "$host_pid"
+host_pid=''
+
+jq -e 'select(.event == "host.direct-traffic" and .status == "verified")' "$host_log" >/dev/null
+jq -e 'select(.event == "host.deregistered" and .status == "complete")' "$host_log" >/dev/null
+jq -e 'select(.event == "join.direct-traffic" and .status == "verified")' "$join_log" >/dev/null
+jq -e 'select(.event == "join.outcome-report" and .status == "accepted")' "$join_log" >/dev/null
+
+printf 'Rendezvous deployment smoke passed: HTTP live/ready and authenticated UDP mediation/direct traffic.\n'

src/FinalFactory.Rendezvous.Client/ConnectionOutcomes/RendezvousConnectionOutcome.cs

@@ -0,0 +1,183 @@
+using FinalFactory.Rendezvous.Contracts;
+using LiteNetLib;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public enum RendezvousConnectionOutcomeSource
+{
+    RendezvousService = 1,
+    LocalTraversal = 2,
+    RemoteHost = 3,
+    Caller = 4,
+    Lifecycle = 5,
+}
+
+public enum RendezvousConnectionFailureCategory
+{
+    None = 0,
+    Directory = 1,
+    Compatibility = 2,
+    Authorization = 3,
+    Capacity = 4,
+    HostPresence = 5,
+    Service = 6,
+    Mediation = 7,
+    NatTraversal = 8,
+    DirectConnection = 9,
+    Lifecycle = 10,
+}
+
+public enum RendezvousConnectionPhase
+{
+    Directory = 1,
+    Authorization = 2,
+    Mediation = 3,
+    NatTraversal = 4,
+    DirectConnection = 5,
+    Complete = 6,
+}
+
+public sealed class RendezvousConnectionOutcome
+{
+    private readonly NetworkEndpoint? _dedicatedFallback;
+
+    private RendezvousConnectionOutcome(
+        ConnectionOutcomeKind kind,
+        RendezvousConnectionOutcomeSource source,
+        RendezvousConnectionFailureCategory category,
+        RendezvousConnectionPhase phase,
+        TimeSpan elapsed,
+        RendezvousErrorCode? serviceError,
+        NetworkEndpoint? dedicatedFallback,
+        NetPeer? peer)
+    {
+        if (elapsed < TimeSpan.Zero)
+        {
+            throw new ArgumentOutOfRangeException(nameof(elapsed));
+        }
+
+        if (dedicatedFallback is not null
+            && !ContractValidation.IsNetworkEndpointValid(dedicatedFallback))
+        {
+            throw new ArgumentException("The dedicated fallback endpoint is invalid.", nameof(dedicatedFallback));
+        }
+
+        Kind = kind;
+        Source = source;
+        Category = category;
+        Phase = phase;
+        Elapsed = elapsed;
+        ServiceError = serviceError;
+        _dedicatedFallback = RendezvousEndpoint.Copy(dedicatedFallback);
+        Peer = peer;
+    }
+
+    public ConnectionOutcomeKind Kind { get; }
+    public RendezvousConnectionOutcomeSource Source { get; }
+    public RendezvousConnectionFailureCategory Category { get; }
+    public RendezvousConnectionPhase Phase { get; }
+    public TimeSpan Elapsed { get; }
+    public RendezvousErrorCode? ServiceError { get; }
+    public NetworkEndpoint? DedicatedFallback => RendezvousEndpoint.Copy(_dedicatedFallback);
+    public NetPeer? Peer { get; }
+    public bool IsSuccess => Kind == ConnectionOutcomeKind.Connected;
+    public bool HasDedicatedFallback => _dedicatedFallback is not null;
+
+    public static RendezvousConnectionOutcome FromServiceError(
+        RendezvousErrorCode error,
+        TimeSpan elapsed,
+        NetworkEndpoint? dedicatedFallback = null)
+    {
+        if (error == RendezvousErrorCode.None)
+        {
+            throw new ArgumentException("A service failure outcome requires an error.", nameof(error));
+        }
+
+        (ConnectionOutcomeKind kind, RendezvousConnectionFailureCategory category, RendezvousConnectionPhase phase) =
+            error switch
+            {
+                RendezvousErrorCode.NotFound => (
+                    ConnectionOutcomeKind.DirectoryNotFound,
+                    RendezvousConnectionFailureCategory.Directory,
+                    RendezvousConnectionPhase.Directory),
+                RendezvousErrorCode.Expired => (
+                    ConnectionOutcomeKind.AttemptExpired,
+                    RendezvousConnectionFailureCategory.Authorization,
+                    RendezvousConnectionPhase.Authorization),
+                RendezvousErrorCode.IncompatibleProtocol => (
+                    ConnectionOutcomeKind.IncompatibleProtocol,
+                    RendezvousConnectionFailureCategory.Compatibility,
+                    RendezvousConnectionPhase.Directory),
+                RendezvousErrorCode.AuthenticationRequired
+                    or RendezvousErrorCode.Forbidden
+                    or RendezvousErrorCode.ReplayRejected => (
+                        ConnectionOutcomeKind.Unauthorized,
+                        RendezvousConnectionFailureCategory.Authorization,
+                        RendezvousConnectionPhase.Authorization),
+                RendezvousErrorCode.RateLimited
+                    or RendezvousErrorCode.CapacityExceeded => (
+                        ConnectionOutcomeKind.RateLimited,
+                        RendezvousConnectionFailureCategory.Capacity,
+                        RendezvousConnectionPhase.Authorization),
+                RendezvousErrorCode.StaleHost => (
+                    ConnectionOutcomeKind.NoHostPresence,
+                    RendezvousConnectionFailureCategory.HostPresence,
+                    RendezvousConnectionPhase.Mediation),
+                RendezvousErrorCode.ServiceUnavailable => (
+                    ConnectionOutcomeKind.ServiceUnavailable,
+                    RendezvousConnectionFailureCategory.Service,
+                    RendezvousConnectionPhase.Authorization),
+                _ => (
+                    ConnectionOutcomeKind.ServiceRejected,
+                    RendezvousConnectionFailureCategory.Service,
+                    RendezvousConnectionPhase.Authorization),
+            };
+        return new(
+            kind,
+            RendezvousConnectionOutcomeSource.RendezvousService,
+            category,
+            phase,
+            elapsed,
+            error,
+            dedicatedFallback,
+            null);
+    }
+
+    public static ConnectionElapsedBucket BucketElapsed(TimeSpan elapsed)
+    {
+        if (elapsed < TimeSpan.Zero)
+        {
+            throw new ArgumentOutOfRangeException(nameof(elapsed));
+        }
+
+        return elapsed.TotalSeconds switch
+        {
+            < 1 => ConnectionElapsedBucket.UnderOneSecond,
+            < 5 => ConnectionElapsedBucket.OneToFiveSeconds,
+            < 15 => ConnectionElapsedBucket.FiveToFifteenSeconds,
+            < 30 => ConnectionElapsedBucket.FifteenToThirtySeconds,
+            _ => ConnectionElapsedBucket.ThirtySecondsOrMore,
+        };
+    }
+
+    public override string ToString() =>
+        $"[RendezvousConnectionOutcome {Kind}; {Source}; credentials redacted]";
+
+    internal static RendezvousConnectionOutcome Create(
+        ConnectionOutcomeKind kind,
+        RendezvousConnectionOutcomeSource source,
+        RendezvousConnectionFailureCategory category,
+        RendezvousConnectionPhase phase,
+        TimeSpan elapsed,
+        NetworkEndpoint? dedicatedFallback = null,
+        NetPeer? peer = null) => new(
+            kind,
+            source,
+            category,
+            phase,
+            elapsed,
+            null,
+            dedicatedFallback,
+            peer);
+
+}

src/FinalFactory.Rendezvous.Client/ConnectionOutcomes/RendezvousConnectionStartResult.cs

@@ -0,0 +1,35 @@
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public sealed class RendezvousConnectionStartResult
+{
+    internal RendezvousConnectionStartResult(
+        CreateJoinAttemptResponse? attempt,
+        RendezvousConnectionOutcome? outcome)
+    {
+        if ((attempt is null) == (outcome is null))
+        {
+            throw new ArgumentException(
+                "A connection start result requires exactly one attempt or terminal outcome.");
+        }
+
+        Attempt = attempt;
+        Outcome = outcome;
+    }
+
+    public CreateJoinAttemptResponse? Attempt { get; }
+    public RendezvousConnectionOutcome? Outcome { get; }
+    public bool IsReadyForTraversal => Attempt is not null;
+    public bool IsCompleted => Outcome is not null;
+
+    public static RendezvousConnectionStartResult ReadyForTraversal(
+        CreateJoinAttemptResponse attempt) => new(
+        attempt ?? throw new ArgumentNullException(nameof(attempt)),
+        null);
+
+    public static RendezvousConnectionStartResult Completed(
+        RendezvousConnectionOutcome outcome) => new(
+        null,
+        outcome ?? throw new ArgumentNullException(nameof(outcome)));
+}

src/FinalFactory.Rendezvous.Client/JoinAttempts/RendezvousJoinClient.cs

@@ -0,0 +1,236 @@
+using System.Diagnostics;
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public sealed class RendezvousJoinClient : IRendezvousJoinClient
+{
+    private const string LeaseTokenHeader = "X-Rendezvous-Lease-Token";
+    private const string ClientPunchCapabilityHeader = "X-Rendezvous-Client-Punch-Capability";
+
+    private readonly RendezvousHttpTransport _transport;
+
+    public RendezvousJoinClient(
+        HttpClient httpClient,
+        RendezvousClientOptions? options = null,
+        IRendezvousDelay? delay = null)
+    {
+        _transport = new(httpClient, options, delay);
+    }
+
+    public Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
+        CreateJoinAttemptRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        if (request is null)
+        {
+            throw new ArgumentNullException(nameof(request));
+        }
+        CreateJoinAttemptRequest body = new()
+        {
+            ContractVersion = request.ContractVersion,
+            IdempotencyKey = request.IdempotencyKey,
+            GameId = request.GameId,
+            EnvironmentId = request.EnvironmentId,
+            ListingId = request.ListingId,
+            ProtocolVersion = request.ProtocolVersion,
+        };
+        return _transport.SendSafeAsync<CreateJoinAttemptResponse>(
+            () => RendezvousHttpTransport.JsonRequest(HttpMethod.Post, "v1/join-attempts", body),
+            cancellationToken);
+    }
+
+    public async Task<RendezvousConnectionStartResult> CreateConnectionAttemptAsync(
+        CreateJoinAttemptRequest request,
+        NetworkEndpoint? dedicatedFallback = null,
+        CancellationToken cancellationToken = default)
+    {
+        if (dedicatedFallback is not null
+            && !ContractValidation.IsNetworkEndpointValid(dedicatedFallback))
+        {
+            throw new ArgumentException("The dedicated fallback endpoint is invalid.", nameof(dedicatedFallback));
+        }
+
+        Stopwatch elapsed = Stopwatch.StartNew();
+        try
+        {
+            RendezvousClientResult<CreateJoinAttemptResponse> result = await CreateAsync(
+                request,
+                cancellationToken).ConfigureAwait(false);
+            elapsed.Stop();
+            return result.IsSuccess && result.Value is not null
+                ? RendezvousConnectionStartResult.ReadyForTraversal(result.Value)
+                : RendezvousConnectionStartResult.Completed(
+                    RendezvousConnectionOutcome.FromServiceError(
+                        result.Error,
+                        elapsed.Elapsed,
+                        dedicatedFallback));
+        }
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+        {
+            elapsed.Stop();
+            return RendezvousConnectionStartResult.Completed(
+                RendezvousConnectionOutcome.Create(
+                    ConnectionOutcomeKind.Cancelled,
+                    RendezvousConnectionOutcomeSource.Caller,
+                    RendezvousConnectionFailureCategory.Lifecycle,
+                    RendezvousConnectionPhase.Authorization,
+                    elapsed.Elapsed,
+                    dedicatedFallback));
+        }
+    }
+
+    public Task<RendezvousClientResult<bool>> CancelAsync(
+        CreateJoinAttemptResponse attempt,
+        CancellationToken cancellationToken = default)
+    {
+        if (attempt is null)
+        {
+            throw new ArgumentNullException(nameof(attempt));
+        }
+        return _transport.SendSafeAsync<bool>(
+            () => HeaderRequest(
+                HttpMethod.Delete,
+                $"v1/join-attempts/{attempt.AttemptId}",
+                ClientPunchCapabilityHeader,
+                RequireHeaderValue(attempt.ClientPunchCapability, nameof(attempt))),
+            cancellationToken);
+    }
+
+    public Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
+        PublishedSession session,
+        int pageSize = ContractLimits.BrowserPageMaxItems,
+        string? cursor = null,
+        CancellationToken cancellationToken = default)
+    {
+        if (session is null)
+        {
+            throw new ArgumentNullException(nameof(session));
+        }
+        if (pageSize is < 1 or > ContractLimits.BrowserPageMaxItems)
+        {
+            throw new ArgumentOutOfRangeException(nameof(pageSize));
+        }
+
+        string query = $"v1/sessions/{session.ListingId}/join-attempts"
+            + $"?contractVersion={ContractLimits.ContractVersion}"
+            + $"&pageSize={pageSize}"
+            + (cursor is null ? string.Empty : $"&cursor={Uri.EscapeDataString(cursor)}");
+        return _transport.SendSafeAsync<BrowseHostJoinAttemptsResponse>(
+            () => HeaderRequest(
+                HttpMethod.Get,
+                query,
+                LeaseTokenHeader,
+                RequireHeaderValue(session.LeaseToken, nameof(session))),
+            cancellationToken);
+    }
+
+    public async Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
+        PublishedSession session,
+        int maximumPages = 100,
+        CancellationToken cancellationToken = default)
+    {
+        if (session is null)
+        {
+            throw new ArgumentNullException(nameof(session));
+        }
+        if (maximumPages is < 1 or > 1_000)
+        {
+            throw new ArgumentOutOfRangeException(nameof(maximumPages));
+        }
+
+        List<HostJoinAttempt> attempts = [];
+        string? cursor = null;
+        for (int page = 0; page < maximumPages; page++)
+        {
+            RendezvousClientResult<BrowseHostJoinAttemptsResponse> result =
+                await BrowseForHostAsync(
+                    session,
+                    ContractLimits.BrowserPageMaxItems,
+                    cursor,
+                    cancellationToken).ConfigureAwait(false);
+            if (!result.IsSuccess || result.Value is null)
+            {
+                return RendezvousClientResult.Failure<IReadOnlyList<HostJoinAttempt>>(
+                    result.Error,
+                    result.Message,
+                    result.RetryAfterSeconds);
+            }
+
+            attempts.AddRange(result.Value.Items);
+            cursor = result.Value.NextCursor;
+            if (string.IsNullOrEmpty(cursor))
+            {
+                return RendezvousClientResult.Success<IReadOnlyList<HostJoinAttempt>>(
+                    attempts.AsReadOnly());
+            }
+        }
+
+        return RendezvousClientResult.Failure<IReadOnlyList<HostJoinAttempt>>(
+            RendezvousErrorCode.CapacityExceeded,
+            $"Host invitation polling exceeded the configured {maximumPages}-page limit.");
+    }
+
+    public Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
+        CreateJoinAttemptResponse attempt,
+        RendezvousConnectionOutcome outcome,
+        CancellationToken cancellationToken = default)
+    {
+        if (attempt is null)
+        {
+            throw new ArgumentNullException(nameof(attempt));
+        }
+        if (outcome is null)
+        {
+            throw new ArgumentNullException(nameof(outcome));
+        }
+        if (!ContractValidation.IsReportableConnectionOutcome(outcome.Kind))
+        {
+            throw new ArgumentException(
+                "This outcome cannot be reported for an issued join attempt.",
+                nameof(outcome));
+        }
+
+        ReportConnectionOutcomeRequest body = new()
+        {
+            Outcome = outcome.Kind,
+            ElapsedBucket = RendezvousConnectionOutcome.BucketElapsed(outcome.Elapsed),
+        };
+        return _transport.SendSafeAsync<ReportConnectionOutcomeResponse>(
+            () => HeaderJsonRequest(
+                HttpMethod.Post,
+                $"v1/join-attempts/{attempt.AttemptId}/outcome",
+                ClientPunchCapabilityHeader,
+                RequireHeaderValue(attempt.ClientPunchCapability, nameof(attempt)),
+                body),
+            cancellationToken);
+    }
+
+    private static HttpRequestMessage HeaderRequest(
+        HttpMethod method,
+        string uri,
+        string header,
+        string value)
+    {
+        HttpRequestMessage request = new(method, uri);
+        request.Headers.TryAddWithoutValidation(header, value);
+        return request;
+    }
+
+    private static HttpRequestMessage HeaderJsonRequest<T>(
+        HttpMethod method,
+        string uri,
+        string header,
+        string value,
+        T body)
+    {
+        HttpRequestMessage request = RendezvousHttpTransport.JsonRequest(method, uri, body);
+        request.Headers.TryAddWithoutValidation(header, value);
+        return request;
+    }
+
+    private static string RequireHeaderValue(string value, string parameterName) =>
+        !string.IsNullOrWhiteSpace(value)
+            ? value
+            : throw new ArgumentException("The required capability is missing.", parameterName);
+}

src/FinalFactory.Rendezvous.Client/README.md

@@ -1,6 +1,6 @@
 # FinalFactory.Rendezvous.Client
 
-Godot-independent .NET publisher and session-browser SDK for Rendezvous v1.
+Godot-independent .NET publisher, browser, join, and LiteNetLib traversal SDK for Rendezvous v1.
 The package targets `netstandard2.1` and uses a caller-owned `HttpClient`.
 
 ```csharp
@@ -29,6 +29,12 @@ RendezvousClientResult<PublishedSession> registered = await publisher.RegisterAs
         DisplayName = "My server",
         Visibility = ListingVisibility.Public,
         Capacity = new() { CurrentPlayers = 1, MaximumPlayers = 8 },
+        DedicatedFallback = new()
+        {
+            AddressFamily = AddressFamilyKind.Ipv4,
+            Address = "203.0.113.40",
+            Port = 7777,
+        },
     },
     publisherCredential,
     cancellationToken);
@@ -53,10 +59,106 @@ string presenceToken = NatPunchRequestTokenCodec.Encode(
 gameplayNetManager.NatPunchModule.SendNatIntroduceRequest(mediator, presenceToken);
 ```
 
-The same codec creates `Host` tokens for host-polled invitations and `Client`
-tokens for a created join attempt. Always send them from the same LiteNetLib
-socket that will carry the direct game connection; the mediator ignores any
-caller-supplied public endpoint.
+For direct connections, let the SDK drive those tokens from the same caller-owned
+LiteNetLib socket that carries gameplay. Ask the routing listener to create the
+bound manager, then configure and start that caller-owned manager yourself. The
+factory does not open a socket, and synchronized events must remain enabled:
+
+```csharp
+RendezvousNetListener networkEvents = new();
+NetManager gameplayNetManager = networkEvents.CreateManager();
+if (!gameplayNetManager.Start(0))
+{
+    throw new InvalidOperationException("The gameplay UDP socket could not start.");
+}
+```
+
+The host polls join invitations asynchronously; that method only queues a
+snapshot and never calls the manager. `Poll()` is the sole SDK path that invokes
+LiteNetLib and dispatches its synchronized callbacks. Call it once per game
+frame on the thread that owns the manager:
+
+```csharp
+RendezvousJoinClient joins = new(http);
+using RendezvousHostCoordinator host = new(
+    gameplayNetManager,
+    networkEvents,
+    mediatorEndPoint,
+    session,
+    joins);
+
+// Run periodically from the game's normal async scheduling path.
+await host.RefreshJoinAttemptsAsync(cancellationToken);
+
+// Godot _Process, Update, or the equivalent main-thread frame callback.
+host.Poll();
+```
+
+Do not also call `gameplayNetManager.PollEvents()` or
+`gameplayNetManager.NatPunchModule.PollEvents()` when a coordinator owns polling.
+The host coordinator refreshes host presence, punches for queued invitations,
+validates the introduction ticket, and accepts the direct request. Subscribe to
+`AttemptCompleted`; a `Connected` result is raised only after LiteNetLib reports
+the accepted peer as connected. Register ordinary gameplay callbacks on
+`networkEvents.GameplayEvents`; the routing listener reserves Rendezvous direct
+requests for ticket validation and forwards every other callback normally.
+
+The joining game first requests an attempt through the typed start API. It returns
+exactly one issued attempt or one terminal service outcome, so service authority
+is not confused with a later locally observed traversal failure:
+
+```csharp
+RendezvousConnectionStartResult start = await joins.CreateConnectionAttemptAsync(
+    createJoinRequest,
+    cancellationToken: cancellationToken);
+if (start.Outcome is { } serviceOutcome)
+{
+    ShowConnectionFailure(serviceOutcome.Kind, serviceOutcome.Category);
+    return;
+}
+
+CreateJoinAttemptResponse attempt = start.Attempt
+    ?? throw new InvalidOperationException("The typed start result was invalid.");
+using RendezvousClientCoordinator client = new(
+    gameplayNetManager,
+    networkEvents,
+    mediatorEndPoint,
+    attempt);
+
+// Godot _Process, Update, or the equivalent main-thread frame callback.
+client.Poll();
+```
+
+NAT introduction changes the client state to `Connecting`; it is not success.
+Only a `Connected` outcome supplies `Peer`. Completion exposes a stable kind,
+source, category, phase, and elapsed duration. The default HTTP silence, punch,
+and direct-connect budgets are five, ten, and five seconds respectively; configure
+them through `RendezvousClientOptions` and `RendezvousCoordinatorOptions` when a
+game has measured reasons to do so. The signed attempt expiry is always the
+absolute upper bound.
+
+Call `Cancel()` and then `Poll()` for local cancellation, or
+`CancelAsync(joins, cancellationToken)` to also revoke the service attempt.
+Terminal client paths complete exactly once and release all event subscriptions,
+so late packets and callbacks are inert. Disposing a coordinator never stops or
+disposes the caller-owned manager and does not touch an in-flight peer; call
+`Cancel()` followed by `Poll()` first when that peer must also be disconnected.
+
+After terminal completion, reporting is explicit and safe to retry. It sends only
+the authenticated outcome enum and a coarse elapsed bucket—never the endpoint,
+exact duration, diagnostic text, metadata, or player identity:
+
+```csharp
+RendezvousClientResult<ReportConnectionOutcomeResponse> report =
+    await client.ReportOutcomeAsync(joins, cancellationToken);
+```
+
+An optional `DedicatedFallback` is copied from the authoritative listing into the
+issued attempt and terminal outcome. A local deployment may replace it with
+`RendezvousCoordinatorOptions.DedicatedFallbackOverride`. The SDK only returns
+the endpoint; it never connects automatically. The game must explicitly decide
+whether to use it and then connect and authenticate through its own gameplay
+transport. If the outcome has no fallback, v1 offers no relay.
 
 Lease renewal is explicit and caller-controlled:
 
@@ -90,5 +192,6 @@ apply its own player identity, capacity, ban, and gameplay admission rules. Revo
 the attempt on cancellation and dispose the validator during host shutdown so its
 keyed ticket digests are zeroed.
 
-See the repository's ADR 0007 for HTTP ownership/retry semantics and ADR 0008 for
-join-capability and connection-ticket security semantics.
+See the repository's ADR 0007 for HTTP ownership/retry semantics, ADR 0008 for
+join-capability and connection-ticket security semantics, and ADR 0010 for typed
+outcomes, deadlines, reporting, and caller-owned fallback.

src/FinalFactory.Rendezvous.Client/RendezvousClientAbstractions.cs

@@ -42,6 +42,10 @@ public static class RendezvousClientResult
 
 public sealed class PublishedSession
 {
+    private readonly object _timingGate = new();
+    private DateTimeOffset _expiresAt;
+    private int _leaseRenewAfterSeconds;
+
     internal PublishedSession(RegisterSessionResponse response)
     {
         ListingId = response.ListingId;
@@ -49,8 +53,8 @@ public sealed class PublishedSession
         LeaseToken = response.LeaseToken;
         HostPresenceHandle = response.HostPresenceHandle;
         HostPresenceCapability = response.HostPresenceCapability;
-        ExpiresAt = response.ExpiresAt;
-        LeaseRenewAfterSeconds = response.LeaseRenewAfterSeconds;
+        _expiresAt = response.ExpiresAt;
+        _leaseRenewAfterSeconds = response.LeaseRenewAfterSeconds;
         HostPresenceRefreshAfterSeconds = response.HostPresenceRefreshAfterSeconds;
     }
 
@@ -59,8 +63,41 @@ public sealed class PublishedSession
     public string LeaseToken { get; }
     public MediationHandle HostPresenceHandle { get; }
     public string HostPresenceCapability { get; }
-    public DateTimeOffset ExpiresAt { get; internal set; }
-    public int LeaseRenewAfterSeconds { get; internal set; }
+    public DateTimeOffset ExpiresAt
+    {
+        get
+        {
+            lock (_timingGate)
+            {
+                return _expiresAt;
+            }
+        }
+        internal set
+        {
+            lock (_timingGate)
+            {
+                _expiresAt = value;
+            }
+        }
+    }
+
+    public int LeaseRenewAfterSeconds
+    {
+        get
+        {
+            lock (_timingGate)
+            {
+                return _leaseRenewAfterSeconds;
+            }
+        }
+        internal set
+        {
+            lock (_timingGate)
+            {
+                _leaseRenewAfterSeconds = value;
+            }
+        }
+    }
     public int HostPresenceRefreshAfterSeconds { get; }
 
     public override string ToString() => $"[PublishedSession {ListingId}; credentials redacted]";
@@ -109,6 +146,38 @@ public interface IRendezvousSessionBrowserClient
         CancellationToken cancellationToken = default);
 }
 
+public interface IRendezvousJoinClient
+{
+    Task<RendezvousConnectionStartResult> CreateConnectionAttemptAsync(
+        CreateJoinAttemptRequest request,
+        NetworkEndpoint? dedicatedFallback = null,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
+        CreateJoinAttemptRequest request,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<bool>> CancelAsync(
+        CreateJoinAttemptResponse attempt,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
+        PublishedSession session,
+        int pageSize = ContractLimits.BrowserPageMaxItems,
+        string? cursor = null,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
+        PublishedSession session,
+        int maximumPages = 100,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
+        CreateJoinAttemptResponse attempt,
+        RendezvousConnectionOutcome outcome,
+        CancellationToken cancellationToken = default);
+}
+
 public interface IRendezvousDelay
 {
     Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken);
@@ -117,6 +186,7 @@ public interface IRendezvousDelay
 public sealed class RendezvousClientOptions
 {
     public int MaximumSafeRetries { get; set; } = 2;
+    public TimeSpan RequestTimeout { get; set; } = TimeSpan.FromSeconds(5);
     public TimeSpan InitialRetryDelay { get; set; } = TimeSpan.FromMilliseconds(200);
     public TimeSpan MaximumRetryDelay { get; set; } = TimeSpan.FromSeconds(2);
     public double JitterRatio { get; set; } = 0.2;
@@ -124,6 +194,8 @@ public sealed class RendezvousClientOptions
     internal void Validate()
     {
         if (MaximumSafeRetries is < 0 or > 5
+            || RequestTimeout <= TimeSpan.Zero
+            || RequestTimeout > TimeSpan.FromSeconds(30)
             || InitialRetryDelay < TimeSpan.Zero
             || MaximumRetryDelay < InitialRetryDelay
             || MaximumRetryDelay > TimeSpan.FromSeconds(30)
@@ -139,3 +211,15 @@ internal sealed class SystemRendezvousDelay : IRendezvousDelay
     public Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken) =>
         Task.Delay(delay, cancellationToken);
 }
+
+internal static class RendezvousEndpoint
+{
+    internal static NetworkEndpoint? Copy(NetworkEndpoint? endpoint) => endpoint is null
+        ? null
+        : new NetworkEndpoint
+        {
+            AddressFamily = endpoint.AddressFamily,
+            Address = endpoint.Address,
+            Port = endpoint.Port,
+        };
+}

src/FinalFactory.Rendezvous.Client/RendezvousHttpTransport.cs

@@ -24,6 +24,7 @@ internal sealed class RendezvousHttpTransport
         _options = new RendezvousClientOptions
         {
             MaximumSafeRetries = suppliedOptions.MaximumSafeRetries,
+            RequestTimeout = suppliedOptions.RequestTimeout,
             InitialRetryDelay = suppliedOptions.InitialRetryDelay,
             MaximumRetryDelay = suppliedOptions.MaximumRetryDelay,
             JitterRatio = suppliedOptions.JitterRatio,
@@ -38,11 +39,15 @@ internal sealed class RendezvousHttpTransport
         for (int attempt = 0; ; attempt++)
         {
             cancellationToken.ThrowIfCancellationRequested();
+            using CancellationTokenSource requestTimeout =
+                CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            requestTimeout.CancelAfter(_options.RequestTimeout);
+            CancellationToken requestCancellation = requestTimeout.Token;
             try
             {
                 using HttpRequestMessage request = requestFactory();
                 using HttpResponseMessage response = await _httpClient
-                    .SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken)
+                    .SendAsync(request, HttpCompletionOption.ResponseHeadersRead, requestCancellation)
                     .ConfigureAwait(false);
                 if (response.IsSuccessStatusCode)
                 {
@@ -54,7 +59,7 @@ internal sealed class RendezvousHttpTransport
                     byte[] payload;
                     try
                     {
-                        payload = await ReadBoundedAsync(response.Content, cancellationToken)
+                        payload = await ReadBoundedAsync(response.Content, requestCancellation)
                             .ConfigureAwait(false);
                     }
                     catch (InvalidDataException)
@@ -81,7 +86,7 @@ internal sealed class RendezvousHttpTransport
                         : RendezvousClientResult.Success(value);
                 }
 
-                ApiError error = await ReadErrorAsync(response, cancellationToken).ConfigureAwait(false);
+                ApiError error = await ReadErrorAsync(response, requestCancellation).ConfigureAwait(false);
                 int? retryAfter = error.RetryAfterSeconds ?? GetRetryAfterSeconds(response.Headers.RetryAfter);
                 if (attempt < _options.MaximumSafeRetries && IsTransient(error.Code))
                 {

src/FinalFactory.Rendezvous.Client/RendezvousPublisherClient.cs

@@ -88,6 +88,7 @@ public sealed class RendezvousPublisherClient : IRendezvousPublisherClient
             DisplayName = request.DisplayName,
             Capacity = CopyCapacity(request.Capacity),
             Metadata = CopyMetadata(request.Metadata),
+            DedicatedFallback = RendezvousEndpoint.Copy(request.DedicatedFallback),
         };
         return _transport.SendSafeAsync<bool>(
             () => RendezvousHttpTransport.JsonRequest(
@@ -138,6 +139,7 @@ public sealed class RendezvousPublisherClient : IRendezvousPublisherClient
         Visibility = request.Visibility,
         Capacity = CopyCapacity(request.Capacity),
         Metadata = CopyMetadata(request.Metadata),
+        DedicatedFallback = RendezvousEndpoint.Copy(request.DedicatedFallback),
     };
 
     private static SessionCapacity CopyCapacity(SessionCapacity capacity) => new()
@@ -148,4 +150,5 @@ public sealed class RendezvousPublisherClient : IRendezvousPublisherClient
 
     private static Dictionary<string, string> CopyMetadata(Dictionary<string, string> metadata) =>
         new(metadata, StringComparer.Ordinal);
+
 }

src/FinalFactory.Rendezvous.Client/Traversal/DirectConnectionRequestCodec.cs

@@ -0,0 +1,83 @@
+using System.Text;
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public sealed class DirectConnectionRequest
+{
+    public JoinAttemptId AttemptId { get; set; }
+    public string ConnectionTicket { get; set; } = string.Empty;
+
+    public override string ToString() =>
+        $"[DirectConnectionRequest {AttemptId}; ticket redacted]";
+}
+
+public static class DirectConnectionRequestCodec
+{
+    public const int EncodedLength = 63;
+
+    private const int MagicLength = 4;
+    private const int AttemptIdLength = 16;
+    private const int TicketLength = ContractLimits.DerivedCredentialCharacters;
+    private static readonly byte[] Magic = [(byte)'R', (byte)'V', (byte)'D', (byte)'1'];
+
+    public static bool IsRendezvousRequest(ReadOnlySpan<byte> encoded) =>
+        encoded.Length >= MagicLength && encoded[..MagicLength].SequenceEqual(Magic);
+
+    public static byte[] Encode(JoinAttemptId attemptId, string connectionTicket)
+    {
+        if (attemptId.Value == Guid.Empty
+            || connectionTicket is null
+            || connectionTicket.Length != TicketLength
+            || !ContractValidation.IsConnectionTicketValid(connectionTicket))
+        {
+            throw new ArgumentException("The direct connection request fields are invalid.");
+        }
+
+        byte[] encoded = new byte[EncodedLength];
+        Magic.CopyTo(encoded, 0);
+        if (!attemptId.Value.TryWriteBytes(encoded.AsSpan(MagicLength, AttemptIdLength)))
+        {
+            throw new InvalidOperationException("The join attempt identifier could not be encoded.");
+        }
+
+        Encoding.ASCII.GetBytes(
+            connectionTicket,
+            0,
+            connectionTicket.Length,
+            encoded,
+            MagicLength + AttemptIdLength);
+        return encoded;
+    }
+
+    public static bool TryDecode(
+        ReadOnlySpan<byte> encoded,
+        out DirectConnectionRequest? request)
+    {
+        request = null;
+        if (encoded.Length != EncodedLength
+            || !encoded[..MagicLength].SequenceEqual(Magic))
+        {
+            return false;
+        }
+
+        Guid attemptId = new(encoded.Slice(MagicLength, AttemptIdLength));
+        if (attemptId == Guid.Empty)
+        {
+            return false;
+        }
+
+        string ticket = Encoding.ASCII.GetString(encoded[(MagicLength + AttemptIdLength)..]);
+        if (!ContractValidation.IsConnectionTicketValid(ticket))
+        {
+            return false;
+        }
+
+        request = new DirectConnectionRequest
+        {
+            AttemptId = new JoinAttemptId(attemptId),
+            ConnectionTicket = ticket,
+        };
+        return true;
+    }
+}

src/FinalFactory.Rendezvous.Client/Traversal/RendezvousClientCoordinator.cs

@@ -0,0 +1,462 @@
+using System.Net;
+using System.Net.Sockets;
+using FinalFactory.Rendezvous.Contracts;
+using LiteNetLib;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public sealed class RendezvousClientCoordinator : IDisposable
+{
+    private readonly NetManager _manager;
+    private readonly RendezvousNetListener _networkEvents;
+    private readonly EventBasedNatPunchListener _punchEvents;
+    private readonly IPEndPoint _mediator;
+    private readonly CreateJoinAttemptResponse _attempt;
+    private readonly IRendezvousCoordinatorClock _clock;
+    private readonly RendezvousCoordinatorOptions _options;
+    private readonly RendezvousPunchRetrySchedule _retry;
+    private readonly object _completionGate = new();
+    private readonly TimeSpan _startedAt;
+    private readonly TimeSpan _attemptDeadline;
+    private readonly TimeSpan _punchDeadline;
+    private readonly NetworkEndpoint? _dedicatedFallback;
+    private NetPeer? _connectingPeer;
+    private IPEndPoint? _directEndpoint;
+    private TimeSpan? _directDeadline;
+    private RendezvousConnectionOutcome? _outcome;
+    private bool _cancelRequested;
+    private int _polling;
+    private bool _subscriptionsReleased;
+    private int _disposed;
+
+    public RendezvousClientCoordinator(
+        NetManager manager,
+        RendezvousNetListener networkEvents,
+        IPEndPoint mediator,
+        CreateJoinAttemptResponse attempt,
+        RendezvousCoordinatorOptions? options = null)
+        : this(
+            manager,
+            networkEvents,
+            mediator,
+            attempt,
+            options,
+            new SystemRendezvousCoordinatorClock())
+    {
+    }
+
+    internal RendezvousClientCoordinator(
+        NetManager manager,
+        RendezvousNetListener networkEvents,
+        IPEndPoint mediator,
+        CreateJoinAttemptResponse attempt,
+        RendezvousCoordinatorOptions? options,
+        IRendezvousCoordinatorClock clock)
+    {
+        _manager = manager ?? throw new ArgumentNullException(nameof(manager));
+        _networkEvents = networkEvents ?? throw new ArgumentNullException(nameof(networkEvents));
+        _punchEvents = _networkEvents.PunchEvents;
+        _mediator = mediator ?? throw new ArgumentNullException(nameof(mediator));
+        _attempt = attempt ?? throw new ArgumentNullException(nameof(attempt));
+        _clock = clock ?? throw new ArgumentNullException(nameof(clock));
+        _options = (options ?? new RendezvousCoordinatorOptions())
+            .CopyAndValidate();
+        _retry = new(_options, _clock);
+
+        RendezvousManagerGuard.Validate(_manager, _networkEvents);
+        DateTimeOffset startedUtc = _clock.UtcNow;
+        if (_mediator.Port is < 1 or > 65_535
+            || _attempt.AttemptId.Value == Guid.Empty
+            || _attempt.MediationHandle.Value == Guid.Empty
+            || !ContractValidation.IsCapabilityValid(_attempt.ClientPunchCapability)
+            || !ContractValidation.IsConnectionTicketValid(_attempt.ConnectionTicketDigest)
+            || _attempt.ExpiresAt <= startedUtc)
+        {
+            throw new ArgumentException("The client traversal inputs are invalid.");
+        }
+
+        _startedAt = _clock.Elapsed;
+        _attemptDeadline = _startedAt + (_attempt.ExpiresAt - startedUtc);
+        _punchDeadline = Min(_attemptDeadline, _startedAt + _options.PunchTimeout);
+        _dedicatedFallback = RendezvousEndpoint.Copy(
+            _options.DedicatedFallbackOverride ?? _attempt.DedicatedFallback);
+
+        _networkEvents.RendezvousPeerConnected += OnPeerConnected;
+        _networkEvents.RendezvousPeerDisconnected += OnPeerDisconnected;
+        _networkEvents.RendezvousNetworkError += OnNetworkError;
+        _punchEvents.NatIntroductionSuccess += OnNatIntroductionSuccess;
+    }
+
+    public event EventHandler<RendezvousConnectionCompletedEventArgs>? Completed;
+
+    public RendezvousConnectionState State { get; private set; } = RendezvousConnectionState.Punching;
+    public NetPeer? ConnectedPeer { get; private set; }
+    public RendezvousConnectionOutcome? Outcome => Volatile.Read(ref _outcome);
+    public bool IsCompleted => Outcome is not null;
+
+    public void Cancel() => Volatile.Write(ref _cancelRequested, true);
+
+    public async Task<RendezvousClientResult<bool>> CancelAsync(
+        IRendezvousJoinClient joinClient,
+        CancellationToken cancellationToken = default)
+    {
+        if (joinClient is null)
+        {
+            throw new ArgumentNullException(nameof(joinClient));
+        }
+
+        ThrowIfDisposed();
+        Cancel();
+        return await joinClient.CancelAsync(_attempt, cancellationToken).ConfigureAwait(false);
+    }
+
+    public Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
+        IRendezvousJoinClient joinClient,
+        CancellationToken cancellationToken = default)
+    {
+        if (joinClient is null)
+        {
+            throw new ArgumentNullException(nameof(joinClient));
+        }
+        ThrowIfDisposed();
+        if (Outcome is null)
+        {
+            throw new InvalidOperationException("The connection attempt has not completed.");
+        }
+
+        return joinClient.ReportOutcomeAsync(_attempt, Outcome, cancellationToken);
+    }
+
+    public void Poll()
+    {
+        ThrowIfDisposed();
+        if (IsCompleted)
+        {
+            return;
+        }
+
+        if (Interlocked.Exchange(ref _polling, 1) != 0)
+        {
+            throw new InvalidOperationException("The Rendezvous coordinator cannot be polled concurrently or recursively.");
+        }
+
+        try
+        {
+            if (Volatile.Read(ref _cancelRequested))
+            {
+                DisconnectPendingPeer();
+                Complete(
+                    RendezvousConnectionState.Cancelled,
+                    ConnectionOutcomeKind.Cancelled,
+                    RendezvousConnectionOutcomeSource.Caller,
+                    RendezvousConnectionFailureCategory.Lifecycle,
+                    CurrentPhase());
+                return;
+            }
+
+            if (!_manager.IsRunning)
+            {
+                CompleteManagerStopped();
+                return;
+            }
+
+            _manager.PollEvents();
+            _manager.NatPunchModule.PollEvents();
+            if (IsCompleted)
+            {
+                return;
+            }
+
+            DateTimeOffset now = _clock.UtcNow;
+            TimeSpan elapsed = _clock.Elapsed;
+            if (Volatile.Read(ref _cancelRequested))
+            {
+                DisconnectPendingPeer();
+                Complete(
+                    RendezvousConnectionState.Cancelled,
+                    ConnectionOutcomeKind.Cancelled,
+                    RendezvousConnectionOutcomeSource.Caller,
+                    RendezvousConnectionFailureCategory.Lifecycle,
+                    CurrentPhase());
+            }
+            else if (!_manager.IsRunning)
+            {
+                CompleteManagerStopped();
+            }
+            else if (now >= _attempt.ExpiresAt || elapsed >= _attemptDeadline)
+            {
+                DisconnectPendingPeer();
+                Complete(
+                    RendezvousConnectionState.TimedOut,
+                    ConnectionOutcomeKind.AttemptExpired,
+                    RendezvousConnectionOutcomeSource.RendezvousService,
+                    RendezvousConnectionFailureCategory.Authorization,
+                    RendezvousConnectionPhase.Authorization);
+            }
+            else if (State == RendezvousConnectionState.Punching)
+            {
+                if (elapsed >= _punchDeadline
+                    || _retry.IsExhausted && _retry.IsDue(elapsed))
+                {
+                    Complete(
+                        RendezvousConnectionState.TimedOut,
+                        ConnectionOutcomeKind.PunchTimedOut,
+                        RendezvousConnectionOutcomeSource.LocalTraversal,
+                        RendezvousConnectionFailureCategory.NatTraversal,
+                        RendezvousConnectionPhase.NatTraversal);
+                    return;
+                }
+
+                if (_retry.IsDue(elapsed))
+                {
+                    _manager.NatPunchModule.SendNatIntroduceRequest(
+                        _mediator,
+                        NatPunchRequestTokenCodec.Encode(
+                            NatPunchPeerRole.Client,
+                            _attempt.MediationHandle,
+                            _attempt.ClientPunchCapability));
+                    _retry.RecordRequest();
+                }
+            }
+            else if (State == RendezvousConnectionState.Connecting
+                && _directDeadline is TimeSpan directDeadline
+                && directDeadline <= elapsed)
+            {
+                DisconnectPendingPeer();
+                Complete(
+                    RendezvousConnectionState.TimedOut,
+                    ConnectionOutcomeKind.DirectConnectTimedOut,
+                    RendezvousConnectionOutcomeSource.LocalTraversal,
+                    RendezvousConnectionFailureCategory.DirectConnection,
+                    RendezvousConnectionPhase.DirectConnection);
+            }
+        }
+        finally
+        {
+            Volatile.Write(ref _polling, 0);
+        }
+    }
+
+    public void Dispose()
+    {
+        if (Interlocked.Exchange(ref _disposed, 1) != 0)
+        {
+            return;
+        }
+
+        if (!IsCompleted)
+        {
+            Complete(
+                RendezvousConnectionState.Disposed,
+                ConnectionOutcomeKind.Disposed,
+                RendezvousConnectionOutcomeSource.Lifecycle,
+                RendezvousConnectionFailureCategory.Lifecycle,
+                CurrentPhase());
+        }
+
+        ReleaseSubscriptions();
+    }
+
+    public override string ToString() =>
+        $"[RendezvousClientCoordinator {_attempt.AttemptId}; credentials redacted]";
+
+    private void OnNatIntroductionSuccess(
+        IPEndPoint target,
+        NatAddressType addressType,
+        string encodedIntroduction)
+    {
+        _ = addressType;
+        if (State != RendezvousConnectionState.Punching
+            || !NatIntroductionTokenCodec.TryDecode(
+                encodedIntroduction,
+                out NatIntroductionToken? introduction)
+            || introduction is null
+            || introduction.AttemptId != _attempt.AttemptId
+            || !NatIntroductionTokenCodec.MatchesDigest(
+                introduction.ConnectionTicket,
+                _attempt.ConnectionTicketDigest))
+        {
+            return;
+        }
+
+        byte[] connectionData = DirectConnectionRequestCodec.Encode(
+            introduction.AttemptId,
+            introduction.ConnectionTicket);
+        _directEndpoint = target;
+        _connectingPeer = _manager.Connect(target, connectionData);
+        if (_connectingPeer is null
+            || _connectingPeer.ConnectionState != ConnectionState.Outgoing)
+        {
+            _connectingPeer = null;
+            Complete(
+                RendezvousConnectionState.Rejected,
+                ConnectionOutcomeKind.TransportError,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.DirectConnection,
+                RendezvousConnectionPhase.DirectConnection);
+            return;
+        }
+
+        State = RendezvousConnectionState.Connecting;
+        _directDeadline = Min(
+            _attemptDeadline,
+            _clock.Elapsed + _options.DirectConnectTimeout);
+    }
+
+    private void OnPeerConnected(NetPeer peer)
+    {
+        if (State != RendezvousConnectionState.Connecting
+            || !ReferenceEquals(peer, _connectingPeer))
+        {
+            return;
+        }
+
+        Complete(
+            RendezvousConnectionState.Connected,
+            ConnectionOutcomeKind.Connected,
+            RendezvousConnectionOutcomeSource.LocalTraversal,
+            RendezvousConnectionFailureCategory.None,
+            RendezvousConnectionPhase.Complete,
+            peer);
+    }
+
+    private void OnPeerDisconnected(NetPeer peer, DisconnectInfo disconnectInfo)
+    {
+        if (State == RendezvousConnectionState.Connecting
+            && ReferenceEquals(peer, _connectingPeer))
+        {
+            ConnectionOutcomeKind kind = disconnectInfo.Reason == DisconnectReason.Timeout
+                ? ConnectionOutcomeKind.DirectConnectTimedOut
+                : disconnectInfo.Reason == DisconnectReason.ConnectionFailed
+                    ? ConnectionOutcomeKind.TransportError
+                    : ConnectionOutcomeKind.HostRejected;
+            Complete(
+                kind == ConnectionOutcomeKind.DirectConnectTimedOut
+                    ? RendezvousConnectionState.TimedOut
+                    : RendezvousConnectionState.Rejected,
+                kind,
+                kind == ConnectionOutcomeKind.HostRejected
+                    ? RendezvousConnectionOutcomeSource.RemoteHost
+                    : RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.DirectConnection,
+                RendezvousConnectionPhase.DirectConnection);
+        }
+    }
+
+    private void OnNetworkError(IPEndPoint endpoint, SocketError socketError)
+    {
+        _ = socketError;
+        if (State == RendezvousConnectionState.Punching && endpoint.Equals(_mediator))
+        {
+            Complete(
+                RendezvousConnectionState.Rejected,
+                ConnectionOutcomeKind.MediatorUnavailable,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.Mediation,
+                RendezvousConnectionPhase.Mediation);
+        }
+        else if (State == RendezvousConnectionState.Connecting
+            && endpoint.Equals(_directEndpoint))
+        {
+            DisconnectPendingPeer();
+            Complete(
+                RendezvousConnectionState.Rejected,
+                ConnectionOutcomeKind.TransportError,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.DirectConnection,
+                RendezvousConnectionPhase.DirectConnection);
+        }
+    }
+
+    private void DisconnectPendingPeer()
+    {
+        if (_connectingPeer is not null && State == RendezvousConnectionState.Connecting)
+        {
+            _connectingPeer.Disconnect();
+        }
+    }
+
+    private void Complete(
+        RendezvousConnectionState terminalState,
+        ConnectionOutcomeKind kind,
+        RendezvousConnectionOutcomeSource source,
+        RendezvousConnectionFailureCategory category,
+        RendezvousConnectionPhase phase,
+        NetPeer? peer = null)
+    {
+        RendezvousConnectionCompletedEventArgs completion;
+        lock (_completionGate)
+        {
+            if (_outcome is not null)
+            {
+                return;
+            }
+
+            RendezvousConnectionOutcome outcome = RendezvousConnectionOutcome.Create(
+                kind,
+                source,
+                category,
+                phase,
+                _clock.Elapsed - _startedAt,
+                ShouldOfferFallback(kind) ? _dedicatedFallback : null,
+                peer);
+            State = terminalState;
+            if (kind == ConnectionOutcomeKind.Connected)
+            {
+                ConnectedPeer = peer;
+            }
+            Volatile.Write(ref _outcome, outcome);
+            ReleaseSubscriptions();
+            completion = new(terminalState, outcome);
+        }
+
+        Completed?.Invoke(this, completion);
+    }
+
+    private void ReleaseSubscriptions()
+    {
+        lock (_completionGate)
+        {
+            if (_subscriptionsReleased)
+            {
+                return;
+            }
+
+            _networkEvents.RendezvousPeerConnected -= OnPeerConnected;
+            _networkEvents.RendezvousPeerDisconnected -= OnPeerDisconnected;
+            _networkEvents.RendezvousNetworkError -= OnNetworkError;
+            _punchEvents.NatIntroductionSuccess -= OnNatIntroductionSuccess;
+            _subscriptionsReleased = true;
+        }
+    }
+
+    private void CompleteManagerStopped() => Complete(
+        RendezvousConnectionState.ManagerStopped,
+        ConnectionOutcomeKind.ManagerStopped,
+        RendezvousConnectionOutcomeSource.Lifecycle,
+        RendezvousConnectionFailureCategory.Lifecycle,
+        CurrentPhase());
+
+    private RendezvousConnectionPhase CurrentPhase() => State switch
+    {
+        RendezvousConnectionState.Punching => RendezvousConnectionPhase.NatTraversal,
+        RendezvousConnectionState.Connecting => RendezvousConnectionPhase.DirectConnection,
+        _ => RendezvousConnectionPhase.Complete,
+    };
+
+    private static bool ShouldOfferFallback(ConnectionOutcomeKind kind) => kind is not (
+        ConnectionOutcomeKind.Connected
+        or ConnectionOutcomeKind.Cancelled
+        or ConnectionOutcomeKind.Disposed);
+
+    private static TimeSpan Min(TimeSpan left, TimeSpan right) =>
+        left <= right ? left : right;
+
+    private void ThrowIfDisposed()
+    {
+        if (Volatile.Read(ref _disposed) != 0)
+        {
+            throw new ObjectDisposedException(nameof(RendezvousClientCoordinator));
+        }
+    }
+}

src/FinalFactory.Rendezvous.Client/Traversal/RendezvousCoordinatorAbstractions.cs

@@ -0,0 +1,228 @@
+using System.Diagnostics;
+using System.Security.Cryptography;
+using FinalFactory.Rendezvous.Contracts;
+using LiteNetLib;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public enum RendezvousConnectionState
+{
+    Punching = 1,
+    Connecting = 2,
+    Connected = 3,
+    Cancelled = 4,
+    TimedOut = 5,
+    Rejected = 6,
+    ManagerStopped = 7,
+    Disposed = 8,
+}
+
+public sealed class RendezvousConnectionCompletedEventArgs : EventArgs
+{
+    [Obsolete("Completion events now expose a typed Outcome. Construct these arguments only for legacy test doubles.")]
+    public RendezvousConnectionCompletedEventArgs(
+        RendezvousConnectionState state,
+        NetPeer? peer)
+        : this(state, RendezvousCompletionInvariant.FromLegacy(state, peer))
+    {
+    }
+
+    internal RendezvousConnectionCompletedEventArgs(
+        RendezvousConnectionState state,
+        RendezvousConnectionOutcome outcome)
+    {
+        RendezvousCompletionInvariant.Validate(state, outcome);
+        State = state;
+        Outcome = outcome;
+    }
+
+    public RendezvousConnectionState State { get; }
+    public RendezvousConnectionOutcome Outcome { get; }
+    public NetPeer? Peer => Outcome.Peer;
+}
+
+internal static class RendezvousCompletionInvariant
+{
+    internal static RendezvousConnectionOutcome FromLegacy(
+        RendezvousConnectionState state,
+        NetPeer? peer) => state switch
+        {
+            RendezvousConnectionState.Connected when peer is not null => RendezvousConnectionOutcome.Create(
+                ConnectionOutcomeKind.Connected,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.None,
+                RendezvousConnectionPhase.Complete,
+                TimeSpan.Zero,
+                peer: peer),
+            RendezvousConnectionState.Cancelled => RendezvousConnectionOutcome.Create(
+                ConnectionOutcomeKind.Cancelled,
+                RendezvousConnectionOutcomeSource.Caller,
+                RendezvousConnectionFailureCategory.Lifecycle,
+                RendezvousConnectionPhase.Complete,
+                TimeSpan.Zero),
+            RendezvousConnectionState.TimedOut => RendezvousConnectionOutcome.Create(
+                ConnectionOutcomeKind.DirectConnectTimedOut,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.DirectConnection,
+                RendezvousConnectionPhase.DirectConnection,
+                TimeSpan.Zero),
+            RendezvousConnectionState.Rejected => RendezvousConnectionOutcome.Create(
+                ConnectionOutcomeKind.HostRejected,
+                RendezvousConnectionOutcomeSource.RemoteHost,
+                RendezvousConnectionFailureCategory.Authorization,
+                RendezvousConnectionPhase.Authorization,
+                TimeSpan.Zero),
+            RendezvousConnectionState.ManagerStopped => RendezvousConnectionOutcome.Create(
+                ConnectionOutcomeKind.ManagerStopped,
+                RendezvousConnectionOutcomeSource.Lifecycle,
+                RendezvousConnectionFailureCategory.Lifecycle,
+                RendezvousConnectionPhase.Complete,
+                TimeSpan.Zero),
+            RendezvousConnectionState.Disposed => RendezvousConnectionOutcome.Create(
+                ConnectionOutcomeKind.Disposed,
+                RendezvousConnectionOutcomeSource.Lifecycle,
+                RendezvousConnectionFailureCategory.Lifecycle,
+                RendezvousConnectionPhase.Complete,
+                TimeSpan.Zero),
+            RendezvousConnectionState.Connected => throw new ArgumentNullException(
+                nameof(peer),
+                "A connected completion requires a peer."),
+            _ => throw new ArgumentOutOfRangeException(
+                nameof(state),
+                state,
+                "A completion event requires a terminal connection state."),
+        };
+
+    internal static void Validate(
+        RendezvousConnectionState state,
+        RendezvousConnectionOutcome outcome)
+    {
+        if (outcome is null)
+        {
+            throw new ArgumentNullException(nameof(outcome));
+        }
+        if ((state == RendezvousConnectionState.Connected) != outcome.IsSuccess)
+        {
+            throw new ArgumentException(
+                "The connection state and typed outcome contradict each other.",
+                nameof(outcome));
+        }
+    }
+}
+
+public sealed class RendezvousCoordinatorOptions
+{
+    public int MaximumPunchRequests { get; set; } = 5;
+    public int MaximumAttemptChecksPerPoll { get; set; } = 128;
+    public TimeSpan InitialPunchRetryDelay { get; set; } = TimeSpan.FromMilliseconds(200);
+    public TimeSpan MaximumPunchRetryDelay { get; set; } = TimeSpan.FromSeconds(2);
+    public TimeSpan PunchTimeout { get; set; } = TimeSpan.FromSeconds(10);
+    public TimeSpan DirectConnectTimeout { get; set; } = TimeSpan.FromSeconds(5);
+    public TimeSpan ConnectionTicketLifetime { get; set; } = TimeSpan.FromSeconds(20);
+    public double JitterRatio { get; set; } = 0.2;
+    public NetworkEndpoint? DedicatedFallbackOverride { get; set; }
+
+    internal RendezvousCoordinatorOptions CopyAndValidate()
+    {
+        if (MaximumPunchRequests is < 1 or > 20
+            || MaximumAttemptChecksPerPoll is < 1 or > 1_024
+            || InitialPunchRetryDelay < TimeSpan.FromMilliseconds(10)
+            || MaximumPunchRetryDelay < InitialPunchRetryDelay
+            || MaximumPunchRetryDelay > TimeSpan.FromSeconds(10)
+            || PunchTimeout <= TimeSpan.Zero
+            || PunchTimeout > TimeSpan.FromSeconds(30)
+            || DirectConnectTimeout <= TimeSpan.Zero
+            || DirectConnectTimeout > TimeSpan.FromSeconds(30)
+            || ConnectionTicketLifetime <= TimeSpan.Zero
+            || ConnectionTicketLifetime > TimeSpan.FromSeconds(20)
+            || JitterRatio is < 0 or > 1
+            || DedicatedFallbackOverride is not null
+                && !ContractValidation.IsNetworkEndpointValid(DedicatedFallbackOverride))
+        {
+            throw new ArgumentOutOfRangeException(nameof(RendezvousCoordinatorOptions));
+        }
+
+        return new RendezvousCoordinatorOptions
+        {
+            MaximumPunchRequests = MaximumPunchRequests,
+            MaximumAttemptChecksPerPoll = MaximumAttemptChecksPerPoll,
+            InitialPunchRetryDelay = InitialPunchRetryDelay,
+            MaximumPunchRetryDelay = MaximumPunchRetryDelay,
+            PunchTimeout = PunchTimeout,
+            DirectConnectTimeout = DirectConnectTimeout,
+            ConnectionTicketLifetime = ConnectionTicketLifetime,
+            JitterRatio = JitterRatio,
+            DedicatedFallbackOverride = RendezvousEndpoint.Copy(DedicatedFallbackOverride),
+        };
+    }
+}
+
+internal interface IRendezvousCoordinatorClock
+{
+    DateTimeOffset UtcNow { get; }
+    TimeSpan Elapsed { get; }
+}
+
+internal sealed class SystemRendezvousCoordinatorClock : IRendezvousCoordinatorClock
+{
+    private readonly long _origin = Stopwatch.GetTimestamp();
+
+    public DateTimeOffset UtcNow => DateTimeOffset.UtcNow;
+    public TimeSpan Elapsed => TimeSpan.FromSeconds(
+        (Stopwatch.GetTimestamp() - _origin) / (double)Stopwatch.Frequency);
+}
+
+internal static class RendezvousManagerGuard
+{
+    internal static void Validate(
+        NetManager manager,
+        RendezvousNetListener networkEvents)
+    {
+        networkEvents.ValidateManager(manager);
+        if (!manager.IsRunning)
+        {
+            throw new InvalidOperationException("The caller-owned LiteNetLib manager must be running.");
+        }
+
+        if (!manager.NatPunchEnabled
+            || manager.UnsyncedEvents
+            || manager.NatPunchModule.UnsyncedEvents)
+        {
+            throw new InvalidOperationException(
+                "The caller-owned manager must enable NAT punching and synchronized event dispatch.");
+        }
+    }
+}
+
+internal sealed class RendezvousPunchRetrySchedule(
+    RendezvousCoordinatorOptions options,
+    IRendezvousCoordinatorClock clock)
+{
+    public int RequestsSent { get; private set; }
+    public TimeSpan NextRequestAt { get; private set; } = TimeSpan.Zero;
+
+    public bool IsExhausted => RequestsSent >= options.MaximumPunchRequests;
+
+    public bool IsDue(TimeSpan elapsed) => elapsed >= NextRequestAt;
+
+    public void RecordRequest()
+    {
+        int exponent = Math.Min(RequestsSent, 30);
+        RequestsSent++;
+        double milliseconds = Math.Min(
+            options.InitialPunchRetryDelay.TotalMilliseconds * Math.Pow(2, exponent),
+            options.MaximumPunchRetryDelay.TotalMilliseconds);
+        if (options.JitterRatio > 0)
+        {
+            Span<byte> random = stackalloc byte[1];
+            RandomNumberGenerator.Fill(random);
+            double unit = random[0] / 255d;
+            double multiplier = 1 - options.JitterRatio + (2 * options.JitterRatio * unit);
+            milliseconds = Math.Min(
+                milliseconds * multiplier,
+                options.MaximumPunchRetryDelay.TotalMilliseconds);
+        }
+
+        NextRequestAt = clock.Elapsed + TimeSpan.FromMilliseconds(milliseconds);
+    }
+}

src/FinalFactory.Rendezvous.Client/Traversal/RendezvousHostCoordinator.cs

@@ -0,0 +1,813 @@
+using System.Net;
+using System.Net.Sockets;
+using FinalFactory.Rendezvous.Contracts;
+using LiteNetLib;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public enum RendezvousHostState
+{
+    Active = 1,
+    ManagerStopped = 2,
+    Disposed = 3,
+}
+
+public sealed class RendezvousHostAttemptCompletedEventArgs : EventArgs
+{
+    [Obsolete("Completion events now expose a typed Outcome. Construct these arguments only for legacy test doubles.")]
+    public RendezvousHostAttemptCompletedEventArgs(
+        JoinAttemptId attemptId,
+        RendezvousConnectionState state,
+        NetPeer? peer)
+        : this(attemptId, state, RendezvousCompletionInvariant.FromLegacy(state, peer))
+    {
+    }
+
+    internal RendezvousHostAttemptCompletedEventArgs(
+        JoinAttemptId attemptId,
+        RendezvousConnectionState state,
+        RendezvousConnectionOutcome outcome)
+    {
+        if (attemptId.Value == Guid.Empty)
+        {
+            throw new ArgumentException("The completed attempt ID is invalid.", nameof(attemptId));
+        }
+
+        RendezvousCompletionInvariant.Validate(state, outcome);
+        AttemptId = attemptId;
+        State = state;
+        Outcome = outcome;
+    }
+
+    public JoinAttemptId AttemptId { get; }
+    public RendezvousConnectionState State { get; }
+    public RendezvousConnectionOutcome Outcome { get; }
+    public NetPeer? Peer => Outcome.Peer;
+}
+
+public sealed class RendezvousHostCoordinator : IDisposable
+{
+    private readonly NetManager _manager;
+    private readonly RendezvousNetListener _networkEvents;
+    private readonly EventBasedNatPunchListener _punchEvents;
+    private readonly IPEndPoint _mediator;
+    private readonly PublishedSession _session;
+    private readonly IRendezvousJoinClient _joinClient;
+    private readonly RendezvousCoordinatorOptions _options;
+    private readonly IRendezvousCoordinatorClock _clock;
+    private readonly ConnectionTicketValidator _tickets;
+    private readonly Dictionary<JoinAttemptId, PendingHostAttempt> _attempts = [];
+    private readonly Dictionary<NetPeer, JoinAttemptId> _acceptedPeers = [];
+    private readonly Dictionary<JoinAttemptId, DeferredConnectionRequest> _deferredRequests = [];
+    private readonly Dictionary<JoinAttemptId, DateTimeOffset> _terminalAttempts = [];
+    private readonly Queue<JoinAttemptId> _attemptSchedule = [];
+    private readonly SortedDictionary<long, Queue<HostAttemptDeadline>> _deadlines = [];
+    private readonly List<JoinAttemptId> _cleanupScratch = [];
+    private HostJoinAttempt[]? _latestSnapshot;
+    private DateTimeOffset _nextPresenceAt = DateTimeOffset.MinValue;
+    private DateTimeOffset _nextTerminalCleanupAt = DateTimeOffset.MinValue;
+    private int _refreshing;
+    private int _polling;
+    private bool _subscriptionsReleased;
+    private int _disposed;
+
+    public RendezvousHostCoordinator(
+        NetManager manager,
+        RendezvousNetListener networkEvents,
+        IPEndPoint mediator,
+        PublishedSession session,
+        IRendezvousJoinClient joinClient,
+        RendezvousCoordinatorOptions? options = null)
+        : this(
+            manager,
+            networkEvents,
+            mediator,
+            session,
+            joinClient,
+            options,
+            new SystemRendezvousCoordinatorClock(),
+            null)
+    {
+    }
+
+    internal RendezvousHostCoordinator(
+        NetManager manager,
+        RendezvousNetListener networkEvents,
+        IPEndPoint mediator,
+        PublishedSession session,
+        IRendezvousJoinClient joinClient,
+        RendezvousCoordinatorOptions? options,
+        IRendezvousCoordinatorClock clock,
+        ConnectionTicketValidator? tickets)
+    {
+        _manager = manager ?? throw new ArgumentNullException(nameof(manager));
+        _networkEvents = networkEvents ?? throw new ArgumentNullException(nameof(networkEvents));
+        _punchEvents = _networkEvents.PunchEvents;
+        _mediator = mediator ?? throw new ArgumentNullException(nameof(mediator));
+        _session = session ?? throw new ArgumentNullException(nameof(session));
+        _joinClient = joinClient ?? throw new ArgumentNullException(nameof(joinClient));
+        _options = (options ?? new RendezvousCoordinatorOptions()).CopyAndValidate();
+        _clock = clock ?? throw new ArgumentNullException(nameof(clock));
+        _tickets = tickets ?? new ConnectionTicketValidator();
+
+        RendezvousManagerGuard.Validate(_manager, _networkEvents);
+        ValidateInputs();
+        _networkEvents.RendezvousConnectionRequest += OnConnectionRequest;
+        _networkEvents.RendezvousPeerConnected += OnPeerConnected;
+        _networkEvents.RendezvousPeerDisconnected += OnPeerDisconnected;
+        _networkEvents.RendezvousNetworkError += OnNetworkError;
+        _punchEvents.NatIntroductionSuccess += OnNatIntroductionSuccess;
+    }
+
+    public event EventHandler<RendezvousHostAttemptCompletedEventArgs>? AttemptCompleted;
+
+    public RendezvousHostState State { get; private set; } = RendezvousHostState.Active;
+    public int PendingAttemptCount => _attempts.Count;
+    internal int DeferredRequestCount => _deferredRequests.Count;
+
+    public async Task<RendezvousClientResult<int>> RefreshJoinAttemptsAsync(
+        CancellationToken cancellationToken = default)
+    {
+        ThrowIfDisposed();
+        if (Interlocked.Exchange(ref _refreshing, 1) != 0)
+        {
+            throw new InvalidOperationException("A host invitation refresh is already running.");
+        }
+
+        try
+        {
+            RendezvousClientResult<IReadOnlyList<HostJoinAttempt>> result =
+                await _joinClient.BrowseAllForHostAsync(
+                    _session,
+                    cancellationToken: cancellationToken).ConfigureAwait(false);
+            if (!result.IsSuccess || result.Value is null)
+            {
+                return RendezvousClientResult.Failure<int>(
+                    result.Error,
+                    result.Message,
+                    result.RetryAfterSeconds);
+            }
+
+            HostJoinAttempt[] snapshot = result.Value.Select(CopyAttempt).ToArray();
+            if (Volatile.Read(ref _disposed) != 0)
+            {
+                throw new ObjectDisposedException(nameof(RendezvousHostCoordinator));
+            }
+
+            Interlocked.Exchange(ref _latestSnapshot, snapshot);
+            if (Volatile.Read(ref _disposed) != 0)
+            {
+                Interlocked.Exchange(ref _latestSnapshot, null);
+                throw new ObjectDisposedException(nameof(RendezvousHostCoordinator));
+            }
+
+            return RendezvousClientResult.Success(snapshot.Length);
+        }
+        finally
+        {
+            Volatile.Write(ref _refreshing, 0);
+        }
+    }
+
+    public void Poll()
+    {
+        ThrowIfDisposed();
+        if (State != RendezvousHostState.Active)
+        {
+            return;
+        }
+
+        if (Interlocked.Exchange(ref _polling, 1) != 0)
+        {
+            throw new InvalidOperationException("The Rendezvous coordinator cannot be polled concurrently or recursively.");
+        }
+
+        try
+        {
+            ApplySnapshots();
+            if (!_manager.IsRunning)
+            {
+                Stop(
+                    RendezvousHostState.ManagerStopped,
+                    RendezvousConnectionState.ManagerStopped,
+                    ConnectionOutcomeKind.ManagerStopped);
+                return;
+            }
+
+            _manager.NatPunchModule.PollEvents();
+            _manager.PollEvents();
+            _manager.NatPunchModule.PollEvents();
+            if (State != RendezvousHostState.Active)
+            {
+                return;
+            }
+
+            DateTimeOffset now = _clock.UtcNow;
+            TimeSpan elapsed = _clock.Elapsed;
+            if (!_manager.IsRunning)
+            {
+                Stop(
+                    RendezvousHostState.ManagerStopped,
+                    RendezvousConnectionState.ManagerStopped,
+                    ConnectionOutcomeKind.ManagerStopped);
+                return;
+            }
+
+            RefreshPresence(now);
+            ProcessDueDeadlines(elapsed);
+            if (State != RendezvousHostState.Active)
+            {
+                return;
+            }
+
+            int checks = Math.Min(
+                _attemptSchedule.Count,
+                _options.MaximumAttemptChecksPerPoll);
+            for (int index = 0; index < checks; index++)
+            {
+                JoinAttemptId attemptId = _attemptSchedule.Dequeue();
+                if (!_attempts.TryGetValue(attemptId, out PendingHostAttempt? attempt))
+                {
+                    continue;
+                }
+
+                if (attempt.State != RendezvousConnectionState.Punching)
+                {
+                    continue;
+                }
+
+                if (attempt.Retry.IsDue(elapsed))
+                {
+                    if (attempt.Retry.IsExhausted)
+                    {
+                        CompleteAttempt(
+                            attemptId,
+                            RendezvousConnectionState.TimedOut,
+                            ConnectionOutcomeKind.PunchTimedOut,
+                            RendezvousConnectionOutcomeSource.LocalTraversal,
+                            RendezvousConnectionFailureCategory.NatTraversal,
+                            RendezvousConnectionPhase.NatTraversal);
+                        continue;
+                    }
+
+                    _manager.NatPunchModule.SendNatIntroduceRequest(
+                        _mediator,
+                        NatPunchRequestTokenCodec.Encode(
+                            NatPunchPeerRole.Host,
+                            attempt.Invitation.MediationHandle,
+                            attempt.Invitation.HostPunchCapability));
+                    attempt.Retry.RecordRequest();
+                }
+
+                _attemptSchedule.Enqueue(attemptId);
+            }
+
+            if (now >= _nextTerminalCleanupAt)
+            {
+                _cleanupScratch.Clear();
+                foreach (KeyValuePair<JoinAttemptId, DateTimeOffset> terminal in _terminalAttempts)
+                {
+                    if (terminal.Value <= now)
+                    {
+                        _cleanupScratch.Add(terminal.Key);
+                    }
+                }
+
+                foreach (JoinAttemptId attemptId in _cleanupScratch)
+                {
+                    _terminalAttempts.Remove(attemptId);
+                }
+
+                _nextTerminalCleanupAt = now + TimeSpan.FromSeconds(1);
+            }
+        }
+        finally
+        {
+            Volatile.Write(ref _polling, 0);
+        }
+    }
+
+    public void Dispose()
+    {
+        if (Interlocked.Exchange(ref _disposed, 1) != 0)
+        {
+            return;
+        }
+
+        Stop(
+            RendezvousHostState.Disposed,
+            RendezvousConnectionState.Disposed,
+            ConnectionOutcomeKind.Disposed);
+        Interlocked.Exchange(ref _latestSnapshot, null);
+        _attemptSchedule.Clear();
+        _deadlines.Clear();
+        _terminalAttempts.Clear();
+        _cleanupScratch.Clear();
+        _tickets.Dispose();
+    }
+
+    public override string ToString() =>
+        $"[RendezvousHostCoordinator {_session.ListingId}; credentials redacted]";
+
+    private void ApplySnapshots()
+    {
+        HostJoinAttempt[]? latest = Interlocked.Exchange(ref _latestSnapshot, null);
+
+        if (latest is null)
+        {
+            return;
+        }
+
+        DateTimeOffset now = _clock.UtcNow;
+        TimeSpan elapsed = _clock.Elapsed;
+        foreach (HostJoinAttempt invitation in latest)
+        {
+            if (invitation.AttemptId.Value == Guid.Empty
+                || invitation.MediationHandle.Value == Guid.Empty
+                || !ContractValidation.IsCapabilityValid(invitation.HostPunchCapability)
+                || !ContractValidation.IsConnectionTicketValid(
+                    invitation.ConnectionTicketDigest))
+            {
+                continue;
+            }
+
+            if (invitation.IsCancelled)
+            {
+                if (_attempts.ContainsKey(invitation.AttemptId))
+                {
+                    CompleteAttempt(
+                        invitation.AttemptId,
+                        RendezvousConnectionState.Cancelled,
+                        ConnectionOutcomeKind.Cancelled,
+                        RendezvousConnectionOutcomeSource.RendezvousService,
+                        RendezvousConnectionFailureCategory.Lifecycle,
+                        RendezvousConnectionPhase.Authorization);
+                }
+
+                _terminalAttempts[invitation.AttemptId] = invitation.ExpiresAt;
+                continue;
+            }
+
+            if (invitation.ExpiresAt <= now
+                || _attempts.ContainsKey(invitation.AttemptId)
+                || _terminalAttempts.ContainsKey(invitation.AttemptId))
+            {
+                continue;
+            }
+
+            TimeSpan attemptDeadline = elapsed + (invitation.ExpiresAt - now);
+            TimeSpan punchDeadline = Min(
+                attemptDeadline,
+                elapsed + _options.PunchTimeout);
+            _attempts.Add(
+                invitation.AttemptId,
+                new PendingHostAttempt(
+                    CopyAttempt(invitation),
+                    new RendezvousPunchRetrySchedule(_options, _clock),
+                    elapsed,
+                    attemptDeadline,
+                    punchDeadline));
+            EnqueueDeadline(
+                new HostAttemptDeadline(
+                    invitation.AttemptId,
+                    RendezvousConnectionState.Punching,
+                    punchDeadline));
+            _attemptSchedule.Enqueue(invitation.AttemptId);
+        }
+    }
+
+    private void RefreshPresence(DateTimeOffset now)
+    {
+        if (now < _nextPresenceAt || now >= _session.ExpiresAt)
+        {
+            return;
+        }
+
+        _manager.NatPunchModule.SendNatIntroduceRequest(
+            _mediator,
+            NatPunchRequestTokenCodec.Encode(
+                NatPunchPeerRole.HostPresence,
+                _session.HostPresenceHandle,
+                _session.HostPresenceCapability));
+        _nextPresenceAt = now + TimeSpan.FromSeconds(_session.HostPresenceRefreshAfterSeconds);
+    }
+
+    private void OnNatIntroductionSuccess(
+        IPEndPoint target,
+        NatAddressType addressType,
+        string encodedIntroduction)
+    {
+        _ = target;
+        _ = addressType;
+        if (!NatIntroductionTokenCodec.TryDecode(
+                encodedIntroduction,
+                out NatIntroductionToken? introduction)
+            || introduction is null
+            || !_attempts.TryGetValue(introduction.AttemptId, out PendingHostAttempt? attempt)
+            || !NatIntroductionTokenCodec.MatchesDigest(
+                introduction.ConnectionTicket,
+                attempt.Invitation.ConnectionTicketDigest)
+            || !_tickets.TryAuthorize(
+                introduction.AttemptId,
+                introduction.ConnectionTicket,
+                Min(
+                    attempt.Invitation.ExpiresAt,
+                    _clock.UtcNow + _options.ConnectionTicketLifetime)))
+        {
+            return;
+        }
+
+        attempt.State = RendezvousConnectionState.Connecting;
+        attempt.DirectDeadline = Min(
+            attempt.AttemptDeadline,
+            _clock.Elapsed + _options.DirectConnectTimeout);
+        EnqueueDeadline(new HostAttemptDeadline(
+            introduction.AttemptId,
+            RendezvousConnectionState.Connecting,
+            attempt.DirectDeadline.Value));
+        if (_deferredRequests.Remove(
+                introduction.AttemptId,
+                out DeferredConnectionRequest? deferred))
+        {
+            AcceptAuthorizedRequest(
+                introduction.AttemptId,
+                attempt,
+                deferred.Request,
+                deferred.ConnectionTicket);
+        }
+    }
+
+    private void OnConnectionRequest(ConnectionRequest request)
+    {
+        ReadOnlySpan<byte> data = request.Data.GetRemainingBytesSpan();
+        if (!DirectConnectionRequestCodec.IsRendezvousRequest(data))
+        {
+            return;
+        }
+
+        if (!DirectConnectionRequestCodec.TryDecode(data, out DirectConnectionRequest? connection)
+            || connection is null
+            || !_attempts.TryGetValue(connection.AttemptId, out PendingHostAttempt? attempt)
+            || !NatIntroductionTokenCodec.MatchesDigest(
+                connection.ConnectionTicket,
+                attempt.Invitation.ConnectionTicketDigest))
+        {
+            request.RejectForce([]);
+            return;
+        }
+
+        if (attempt.State == RendezvousConnectionState.Punching)
+        {
+            _deferredRequests[connection.AttemptId] = new(
+                request,
+                connection.ConnectionTicket);
+            return;
+        }
+
+        if (attempt.State != RendezvousConnectionState.Connecting)
+        {
+            request.RejectForce([]);
+            return;
+        }
+
+        AcceptAuthorizedRequest(
+            connection.AttemptId,
+            attempt,
+            request,
+            connection.ConnectionTicket);
+    }
+
+    private void OnPeerConnected(NetPeer peer)
+    {
+        if (_acceptedPeers.TryGetValue(peer, out JoinAttemptId attemptId))
+        {
+            CompleteAttempt(
+                attemptId,
+                RendezvousConnectionState.Connected,
+                ConnectionOutcomeKind.Connected,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.None,
+                RendezvousConnectionPhase.Complete,
+                peer);
+        }
+    }
+
+    private void OnPeerDisconnected(NetPeer peer, DisconnectInfo disconnectInfo)
+    {
+        _ = disconnectInfo;
+        if (_acceptedPeers.TryGetValue(peer, out JoinAttemptId attemptId))
+        {
+            ConnectionOutcomeKind kind = disconnectInfo.Reason == DisconnectReason.Timeout
+                ? ConnectionOutcomeKind.DirectConnectTimedOut
+                : ConnectionOutcomeKind.TransportError;
+            CompleteAttempt(
+                attemptId,
+                kind == ConnectionOutcomeKind.DirectConnectTimedOut
+                    ? RendezvousConnectionState.TimedOut
+                    : RendezvousConnectionState.Rejected,
+                kind,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.DirectConnection,
+                RendezvousConnectionPhase.DirectConnection);
+        }
+    }
+
+    private void OnNetworkError(IPEndPoint endpoint, SocketError socketError)
+    {
+        _ = socketError;
+        if (!endpoint.Equals(_mediator))
+        {
+            return;
+        }
+
+        foreach (JoinAttemptId attemptId in _attempts
+                     .Where(static item => item.Value.State == RendezvousConnectionState.Punching)
+                     .Select(static item => item.Key)
+                     .ToArray())
+        {
+            CompleteAttempt(
+                attemptId,
+                RendezvousConnectionState.Rejected,
+                ConnectionOutcomeKind.MediatorUnavailable,
+                RendezvousConnectionOutcomeSource.LocalTraversal,
+                RendezvousConnectionFailureCategory.Mediation,
+                RendezvousConnectionPhase.Mediation);
+        }
+    }
+
+    private void CompleteAttempt(
+        JoinAttemptId attemptId,
+        RendezvousConnectionState state,
+        ConnectionOutcomeKind kind,
+        RendezvousConnectionOutcomeSource source,
+        RendezvousConnectionFailureCategory category,
+        RendezvousConnectionPhase phase,
+        NetPeer? peer = null)
+    {
+        if (TryCompleteAttempt(
+                attemptId,
+                state,
+                kind,
+                source,
+                category,
+                phase,
+                peer,
+                out RendezvousHostAttemptCompletedEventArgs? completion))
+        {
+            AttemptCompleted?.Invoke(this, completion!);
+        }
+    }
+
+    private bool TryCompleteAttempt(
+        JoinAttemptId attemptId,
+        RendezvousConnectionState state,
+        ConnectionOutcomeKind kind,
+        RendezvousConnectionOutcomeSource source,
+        RendezvousConnectionFailureCategory category,
+        RendezvousConnectionPhase phase,
+        NetPeer? peer,
+        out RendezvousHostAttemptCompletedEventArgs? completion)
+    {
+        completion = null;
+        if (!_attempts.Remove(attemptId, out PendingHostAttempt? attempt))
+        {
+            return false;
+        }
+
+        if (attempt.AcceptedPeer is not null)
+        {
+            _acceptedPeers.Remove(attempt.AcceptedPeer);
+            if (kind != ConnectionOutcomeKind.Connected)
+            {
+                attempt.AcceptedPeer.Disconnect();
+            }
+        }
+
+        if (_deferredRequests.Remove(attemptId, out DeferredConnectionRequest? deferred))
+        {
+            deferred.Request.RejectForce([]);
+        }
+        _tickets.Revoke(attemptId);
+        _terminalAttempts[attemptId] = attempt.Invitation.ExpiresAt;
+        RendezvousConnectionOutcome outcome = RendezvousConnectionOutcome.Create(
+            kind,
+            source,
+            category,
+            phase,
+            _clock.Elapsed - attempt.StartedAt,
+            peer: peer);
+        completion = new(attemptId, state, outcome);
+        return true;
+    }
+
+    private void Stop(
+        RendezvousHostState hostState,
+        RendezvousConnectionState attemptState,
+        ConnectionOutcomeKind outcomeKind)
+    {
+        if (State != RendezvousHostState.Active)
+        {
+            return;
+        }
+
+        State = hostState;
+        List<RendezvousHostAttemptCompletedEventArgs> completions = [];
+        foreach (JoinAttemptId attemptId in _attempts.Keys.ToArray())
+        {
+            RendezvousConnectionPhase phase = _attempts[attemptId].State
+                == RendezvousConnectionState.Connecting
+                    ? RendezvousConnectionPhase.DirectConnection
+                    : RendezvousConnectionPhase.NatTraversal;
+            if (TryCompleteAttempt(
+                    attemptId,
+                    attemptState,
+                    outcomeKind,
+                    RendezvousConnectionOutcomeSource.Lifecycle,
+                    RendezvousConnectionFailureCategory.Lifecycle,
+                    phase,
+                    null,
+                    out RendezvousHostAttemptCompletedEventArgs? completion))
+            {
+                completions.Add(completion!);
+            }
+        }
+
+        ReleaseSubscriptions();
+        foreach (RendezvousHostAttemptCompletedEventArgs completion in completions)
+        {
+            AttemptCompleted?.Invoke(this, completion);
+        }
+    }
+
+    private void ReleaseSubscriptions()
+    {
+        if (_subscriptionsReleased)
+        {
+            return;
+        }
+
+        _networkEvents.RendezvousConnectionRequest -= OnConnectionRequest;
+        _networkEvents.RendezvousPeerConnected -= OnPeerConnected;
+        _networkEvents.RendezvousPeerDisconnected -= OnPeerDisconnected;
+        _networkEvents.RendezvousNetworkError -= OnNetworkError;
+        _punchEvents.NatIntroductionSuccess -= OnNatIntroductionSuccess;
+        _subscriptionsReleased = true;
+    }
+
+    private void ValidateInputs()
+    {
+        if (_mediator.Port is < 1 or > 65_535
+            || _session.HostPresenceHandle.Value == Guid.Empty
+            || !ContractValidation.IsCapabilityValid(_session.HostPresenceCapability)
+            || _session.HostPresenceRefreshAfterSeconds < 1
+            || _session.ExpiresAt <= _clock.UtcNow)
+        {
+            throw new ArgumentException("The host traversal inputs are invalid.");
+        }
+    }
+
+    private static HostJoinAttempt CopyAttempt(HostJoinAttempt attempt) => new()
+    {
+        AttemptId = attempt.AttemptId,
+        MediationHandle = attempt.MediationHandle,
+        HostPunchCapability = attempt.HostPunchCapability,
+        ConnectionTicketDigest = attempt.ConnectionTicketDigest,
+        IsCancelled = attempt.IsCancelled,
+        ExpiresAt = attempt.ExpiresAt,
+    };
+
+    private static TimeSpan Min(TimeSpan left, TimeSpan right) =>
+        left <= right ? left : right;
+
+    private static DateTimeOffset Min(DateTimeOffset left, DateTimeOffset right) =>
+        left <= right ? left : right;
+
+    private void EnqueueDeadline(HostAttemptDeadline deadline)
+    {
+        if (!_deadlines.TryGetValue(deadline.Deadline.Ticks, out Queue<HostAttemptDeadline>? bucket))
+        {
+            bucket = new Queue<HostAttemptDeadline>();
+            _deadlines.Add(deadline.Deadline.Ticks, bucket);
+        }
+
+        bucket.Enqueue(deadline);
+    }
+
+    private void ProcessDueDeadlines(TimeSpan elapsed)
+    {
+        while (_deadlines.Count > 0)
+        {
+            KeyValuePair<long, Queue<HostAttemptDeadline>> first = _deadlines.First();
+            if (first.Key > elapsed.Ticks)
+            {
+                return;
+            }
+
+            HostAttemptDeadline deadline = first.Value.Dequeue();
+            if (first.Value.Count == 0)
+            {
+                _deadlines.Remove(first.Key);
+            }
+
+            if (!_attempts.TryGetValue(deadline.AttemptId, out PendingHostAttempt? attempt)
+                || attempt.State != deadline.ExpectedState
+                || (deadline.ExpectedState == RendezvousConnectionState.Punching
+                    ? attempt.PunchDeadline
+                    : attempt.DirectDeadline) != deadline.Deadline)
+            {
+                continue;
+            }
+
+            bool expired = elapsed >= attempt.AttemptDeadline;
+            CompleteAttempt(
+                deadline.AttemptId,
+                RendezvousConnectionState.TimedOut,
+                expired
+                    ? ConnectionOutcomeKind.AttemptExpired
+                    : deadline.ExpectedState == RendezvousConnectionState.Punching
+                        ? ConnectionOutcomeKind.PunchTimedOut
+                        : ConnectionOutcomeKind.DirectConnectTimedOut,
+                expired
+                    ? RendezvousConnectionOutcomeSource.RendezvousService
+                    : RendezvousConnectionOutcomeSource.LocalTraversal,
+                expired
+                    ? RendezvousConnectionFailureCategory.Authorization
+                    : deadline.ExpectedState == RendezvousConnectionState.Punching
+                        ? RendezvousConnectionFailureCategory.NatTraversal
+                        : RendezvousConnectionFailureCategory.DirectConnection,
+                expired
+                    ? RendezvousConnectionPhase.Authorization
+                    : deadline.ExpectedState == RendezvousConnectionState.Punching
+                        ? RendezvousConnectionPhase.NatTraversal
+                        : RendezvousConnectionPhase.DirectConnection);
+
+            if (State != RendezvousHostState.Active)
+            {
+                return;
+            }
+        }
+    }
+
+    private void AcceptAuthorizedRequest(
+        JoinAttemptId attemptId,
+        PendingHostAttempt attempt,
+        ConnectionRequest request,
+        string connectionTicket)
+    {
+        ConnectionTicketConsumptionResult consumption = _tickets.Consume(
+            attemptId,
+            connectionTicket);
+        if (consumption != ConnectionTicketConsumptionResult.Accepted)
+        {
+            request.RejectForce([]);
+            return;
+        }
+
+        NetPeer peer = request.Accept();
+        attempt.AcceptedPeer = peer;
+        _acceptedPeers[peer] = attemptId;
+    }
+
+    private void ThrowIfDisposed()
+    {
+        if (Volatile.Read(ref _disposed) != 0)
+        {
+            throw new ObjectDisposedException(nameof(RendezvousHostCoordinator));
+        }
+    }
+
+    private sealed class PendingHostAttempt(
+        HostJoinAttempt invitation,
+        RendezvousPunchRetrySchedule retry,
+        TimeSpan startedAt,
+        TimeSpan attemptDeadline,
+        TimeSpan punchDeadline)
+    {
+        internal HostJoinAttempt Invitation { get; } = invitation;
+        internal RendezvousPunchRetrySchedule Retry { get; } = retry;
+        internal TimeSpan StartedAt { get; } = startedAt;
+        internal TimeSpan AttemptDeadline { get; } = attemptDeadline;
+        internal TimeSpan PunchDeadline { get; } = punchDeadline;
+        internal TimeSpan? DirectDeadline { get; set; }
+        internal RendezvousConnectionState State { get; set; } = RendezvousConnectionState.Punching;
+        internal NetPeer? AcceptedPeer { get; set; }
+    }
+
+    private sealed class HostAttemptDeadline(
+        JoinAttemptId attemptId,
+        RendezvousConnectionState expectedState,
+        TimeSpan deadline)
+    {
+        internal JoinAttemptId AttemptId { get; } = attemptId;
+        internal RendezvousConnectionState ExpectedState { get; } = expectedState;
+        internal TimeSpan Deadline { get; } = deadline;
+    }
+
+    private sealed class DeferredConnectionRequest(
+        ConnectionRequest request,
+        string connectionTicket)
+    {
+        internal ConnectionRequest Request { get; } = request;
+        internal string ConnectionTicket { get; } = connectionTicket;
+    }
+}

src/FinalFactory.Rendezvous.Client/Traversal/RendezvousNetListener.cs

@@ -0,0 +1,114 @@
+using System.Net;
+using System.Net.Sockets;
+using LiteNetLib;
+using LiteNetLib.Utils;
+
+namespace FinalFactory.Rendezvous.Client;
+
+public sealed class RendezvousNetListener : INetEventListener
+{
+    private NetManager? _manager;
+
+    public EventBasedNetListener GameplayEvents { get; } = new();
+    public EventBasedNatPunchListener PunchEvents { get; } = new();
+
+    public NetManager CreateManager()
+    {
+        if (_manager is not null)
+        {
+            throw new InvalidOperationException(
+                "This Rendezvous listener is already bound to a LiteNetLib manager.");
+        }
+
+        NetManager manager = new(this) { NatPunchEnabled = true };
+        manager.NatPunchModule.Init(PunchEvents);
+        _manager = manager;
+        return manager;
+    }
+
+    internal event Action<NetPeer>? RendezvousPeerConnected;
+    internal event Action<NetPeer, DisconnectInfo>? RendezvousPeerDisconnected;
+    internal event Action<ConnectionRequest>? RendezvousConnectionRequest;
+    internal event Action<IPEndPoint, SocketError>? RendezvousNetworkError;
+
+    internal void ValidateManager(NetManager manager)
+    {
+        if (!ReferenceEquals(_manager, manager))
+        {
+            throw new InvalidOperationException(
+                "The LiteNetLib manager must be created by this Rendezvous listener.");
+        }
+    }
+
+    public void OnPeerConnected(NetPeer peer)
+    {
+        RendezvousPeerConnected?.Invoke(peer);
+        ((INetEventListener)GameplayEvents).OnPeerConnected(peer);
+    }
+
+    public void OnPeerDisconnected(NetPeer peer, DisconnectInfo disconnectInfo)
+    {
+        RendezvousPeerDisconnected?.Invoke(peer, disconnectInfo);
+        ((INetEventListener)GameplayEvents).OnPeerDisconnected(peer, disconnectInfo);
+    }
+
+    public void OnNetworkError(IPEndPoint endPoint, SocketError socketError)
+    {
+        RendezvousNetworkError?.Invoke(endPoint, socketError);
+        ((INetEventListener)GameplayEvents).OnNetworkError(endPoint, socketError);
+    }
+
+    public void OnNetworkReceive(
+        NetPeer peer,
+        NetPacketReader reader,
+        byte channelNumber,
+        DeliveryMethod deliveryMethod) =>
+        ((INetEventListener)GameplayEvents).OnNetworkReceive(
+            peer,
+            reader,
+            channelNumber,
+            deliveryMethod);
+
+    public void OnNetworkReceiveUnconnected(
+        IPEndPoint remoteEndPoint,
+        NetPacketReader reader,
+        UnconnectedMessageType messageType) =>
+        ((INetEventListener)GameplayEvents).OnNetworkReceiveUnconnected(
+            remoteEndPoint,
+            reader,
+            messageType);
+
+    public void OnNetworkLatencyUpdate(NetPeer peer, int latency) =>
+        ((INetEventListener)GameplayEvents).OnNetworkLatencyUpdate(peer, latency);
+
+    public void OnConnectionRequest(ConnectionRequest request)
+    {
+        int position = request.Data.Position;
+        bool isRendezvous = DirectConnectionRequestCodec.IsRendezvousRequest(
+            request.Data.GetRemainingBytesSpan());
+        request.Data.SetPosition(position);
+        if (!isRendezvous)
+        {
+            ((INetEventListener)GameplayEvents).OnConnectionRequest(request);
+            return;
+        }
+
+        Action<ConnectionRequest>? handler = RendezvousConnectionRequest;
+        if (handler is null)
+        {
+            request.RejectForce([]);
+            return;
+        }
+
+        handler(request);
+    }
+
+    public void OnMessageDelivered(NetPeer peer, object userData) =>
+        ((INetEventListener)GameplayEvents).OnMessageDelivered(peer, userData);
+
+    public void OnNtpResponse(NtpPacket packet) =>
+        ((INetEventListener)GameplayEvents).OnNtpResponse(packet);
+
+    public void OnPeerAddressChanged(NetPeer peer, IPEndPoint previousAddress) =>
+        ((INetEventListener)GameplayEvents).OnPeerAddressChanged(peer, previousAddress);
+}

src/FinalFactory.Rendezvous.Contracts/ContractEnums.cs

@@ -49,6 +49,27 @@ public enum ConnectionOutcomeKind
     HostRejected = 7,
     TransportFailed = 8,
     FallbackOffered = 9,
+    DirectoryNotFound = 10,
+    AttemptExpired = 11,
+    Unauthorized = 12,
+    RateLimited = 13,
+    NoHostPresence = 14,
+    ServiceUnavailable = 15,
+    MediatorUnavailable = 16,
+    PunchTimedOut = 17,
+    DirectConnectTimedOut = 18,
+    TransportError = 19,
+    ManagerStopped = 20,
+    Disposed = 21,
+}
+
+public enum ConnectionElapsedBucket
+{
+    UnderOneSecond = 1,
+    OneToFiveSeconds = 2,
+    FiveToFifteenSeconds = 3,
+    FifteenToThirtySeconds = 4,
+    ThirtySecondsOrMore = 5,
 }
 
 public enum UdpPresenceMessageType : byte

src/FinalFactory.Rendezvous.Contracts/ContractValidation.cs

@@ -45,6 +45,23 @@ public static class ContractValidation
     public static bool IsDiagnosticCodeValid(string? value) =>
         value is null || IsVisibleAsciiWithin(value, ContractLimits.DiagnosticCodeMaxCharacters);
 
+    public static bool IsReportableConnectionOutcome(ConnectionOutcomeKind outcome) => outcome is
+        ConnectionOutcomeKind.Connected
+        or ConnectionOutcomeKind.Cancelled
+        or ConnectionOutcomeKind.TimedOut
+        or ConnectionOutcomeKind.StaleHost
+        or ConnectionOutcomeKind.TransportFailed
+        or ConnectionOutcomeKind.FallbackOffered
+        or ConnectionOutcomeKind.AttemptExpired
+        or ConnectionOutcomeKind.NoHostPresence
+        or ConnectionOutcomeKind.MediatorUnavailable
+        or ConnectionOutcomeKind.PunchTimedOut
+        or ConnectionOutcomeKind.DirectConnectTimedOut
+        or ConnectionOutcomeKind.HostRejected
+        or ConnectionOutcomeKind.TransportError
+        or ConnectionOutcomeKind.ManagerStopped
+        or ConnectionOutcomeKind.Disposed;
+
     public static bool IsBuildVersionValid(string? value) =>
         !string.IsNullOrWhiteSpace(value)
         && IsUtf8LengthWithin(value, ContractLimits.BuildVersionMaxBytes);

src/FinalFactory.Rendezvous.Contracts/Http/ConnectionOutcomeContracts.cs

@@ -0,0 +1,33 @@
+using System.Text.Json.Serialization;
+
+namespace FinalFactory.Rendezvous.Contracts;
+
+public sealed class ReportConnectionOutcomeRequest
+{
+    [JsonRequired]
+    public int ContractVersion { get; set; } = ContractLimits.ContractVersion;
+
+    [JsonRequired]
+    public ConnectionOutcomeKind Outcome { get; set; }
+
+    public ConnectionElapsedBucket ElapsedBucket { get; set; }
+
+    [Obsolete("Use ElapsedBucket. Exact elapsed time is accepted only for v1 compatibility and is not retained.")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
+    public int ElapsedMilliseconds { get; set; }
+
+    [Obsolete("Diagnostic codes are accepted only for v1 compatibility and are not retained.")]
+    public string? DiagnosticCode { get; set; }
+}
+
+public sealed class ReportConnectionOutcomeResponse
+{
+    [JsonRequired]
+    public int ContractVersion { get; set; } = ContractLimits.ContractVersion;
+
+    [JsonRequired]
+    public bool Accepted { get; set; }
+
+    [JsonRequired]
+    public bool IsDuplicate { get; set; }
+}

src/FinalFactory.Rendezvous.Contracts/Http/JoinContracts.cs

@@ -37,6 +37,9 @@ public sealed class CreateJoinAttemptResponse
     [JsonRequired]
     public string ClientPunchCapability { get; set; } = string.Empty;
 
+    [JsonRequired]
+    public string ConnectionTicketDigest { get; set; } = string.Empty;
+
     [JsonRequired]
     public DateTimeOffset ExpiresAt { get; set; }
     public NetworkEndpoint? DedicatedFallback { get; set; }
@@ -53,6 +56,12 @@ public sealed class HostJoinAttempt
     [JsonRequired]
     public string HostPunchCapability { get; set; } = string.Empty;
 
+    [JsonRequired]
+    public string ConnectionTicketDigest { get; set; } = string.Empty;
+
+    [JsonRequired]
+    public bool IsCancelled { get; set; }
+
     [JsonRequired]
     public DateTimeOffset ExpiresAt { get; set; }
 }
@@ -67,26 +76,3 @@ public sealed class BrowseHostJoinAttemptsResponse
 
     public string? NextCursor { get; set; }
 }
-
-public sealed class ReportConnectionOutcomeRequest
-{
-    [JsonRequired]
-    public int ContractVersion { get; set; } = ContractLimits.ContractVersion;
-
-    [JsonRequired]
-    public ConnectionOutcomeKind Outcome { get; set; }
-
-    [JsonRequired]
-    public int ElapsedMilliseconds { get; set; }
-
-    public string? DiagnosticCode { get; set; }
-}
-
-public sealed class ReportConnectionOutcomeResponse
-{
-    [JsonRequired]
-    public int ContractVersion { get; set; } = ContractLimits.ContractVersion;
-
-    [JsonRequired]
-    public bool Accepted { get; set; }
-}

src/FinalFactory.Rendezvous.Contracts/Http/SessionContracts.cs

@@ -39,6 +39,8 @@ public sealed class SessionListing
 
     [JsonRequired]
     public Dictionary<string, string> Metadata { get; set; } = new(StringComparer.Ordinal);
+
+    public NetworkEndpoint? DedicatedFallback { get; set; }
 }
 
 public sealed class RegisterSessionRequest
@@ -75,6 +77,8 @@ public sealed class RegisterSessionRequest
 
     [JsonRequired]
     public Dictionary<string, string> Metadata { get; set; } = new(StringComparer.Ordinal);
+
+    public NetworkEndpoint? DedicatedFallback { get; set; }
 }
 
 public sealed class RegisterSessionResponse
@@ -147,6 +151,8 @@ public sealed class UpdateSessionRequest
 
     [JsonRequired]
     public Dictionary<string, string> Metadata { get; set; } = new(StringComparer.Ordinal);
+
+    public NetworkEndpoint? DedicatedFallback { get; set; }
 }
 
 public sealed class DeleteSessionRequest

src/FinalFactory.Rendezvous.Contracts/Serialization/ContractJson.cs

@@ -25,7 +25,9 @@ public static class ContractJson
 
         options.AllowTrailingCommas = false;
         options.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
-        options.MaxDepth = 8;
+        // Nine is the minimum that lets ASP.NET generate the nullable fallback
+        // OpenAPI schema; the 16 KiB HTTP body limit still bounds parser work.
+        options.MaxDepth = 9;
         options.NumberHandling = JsonNumberHandling.Strict;
         options.PropertyNameCaseInsensitive = false;
         options.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;

src/FinalFactory.Rendezvous.Contracts/Udp/NatIntroductionTokenCodec.cs

@@ -0,0 +1,149 @@
+using System.Security.Cryptography;
+using System.Text;
+
+namespace FinalFactory.Rendezvous.Contracts;
+
+public sealed class NatIntroductionToken
+{
+    public JoinAttemptId AttemptId { get; set; }
+    public string ConnectionTicket { get; set; } = string.Empty;
+
+    public override string ToString() =>
+        $"[NatIntroductionToken {AttemptId}; ticket redacted]";
+}
+
+public static class NatIntroductionTokenCodec
+{
+    public const int EncodedLength = ContractLimits.DerivedCredentialCharacters;
+
+    private const int DecodedLength = 32;
+    private const int AttemptIdLength = 16;
+    private const int AuthenticatorLength = DecodedLength - AttemptIdLength;
+
+    public static string Encode(JoinAttemptId attemptId, string derivedAuthenticator)
+    {
+        if (attemptId.Value == Guid.Empty
+            || !ContractValidation.IsConnectionTicketValid(derivedAuthenticator)
+            || !TryDecodeBase64Url(derivedAuthenticator, out byte[]? authenticator)
+            || authenticator.Length != DecodedLength)
+        {
+            throw new ArgumentException("The NAT introduction token fields are invalid.");
+        }
+
+        byte[] payload = new byte[DecodedLength];
+        try
+        {
+            if (!attemptId.Value.TryWriteBytes(payload.AsSpan(0, AttemptIdLength)))
+            {
+                throw new InvalidOperationException("The join attempt identifier could not be encoded.");
+            }
+
+            authenticator.AsSpan(0, AuthenticatorLength).CopyTo(payload.AsSpan(AttemptIdLength));
+            return EncodeBase64Url(payload);
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(authenticator);
+            CryptographicOperations.ZeroMemory(payload);
+        }
+    }
+
+    public static bool TryDecode(string? encoded, out NatIntroductionToken? token)
+    {
+        token = null;
+        if (!ContractValidation.IsConnectionTicketValid(encoded)
+            || !TryDecodeBase64Url(encoded!, out byte[]? payload)
+            || payload.Length != DecodedLength)
+        {
+            return false;
+        }
+
+        try
+        {
+            Guid attemptId = new(payload.AsSpan(0, AttemptIdLength));
+            if (attemptId == Guid.Empty)
+            {
+                return false;
+            }
+
+            token = new NatIntroductionToken
+            {
+                AttemptId = new JoinAttemptId(attemptId),
+                ConnectionTicket = encoded!,
+            };
+            return true;
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(payload);
+        }
+    }
+
+    public static string ComputeDigest(string connectionTicket)
+    {
+        if (!ContractValidation.IsConnectionTicketValid(connectionTicket))
+        {
+            throw new ArgumentException("The connection ticket is invalid.", nameof(connectionTicket));
+        }
+
+        byte[] encoded = Encoding.ASCII.GetBytes(connectionTicket);
+        byte[] digest;
+        using (SHA256 sha256 = SHA256.Create())
+        {
+            digest = sha256.ComputeHash(encoded);
+        }
+        CryptographicOperations.ZeroMemory(encoded);
+        try
+        {
+            return EncodeBase64Url(digest);
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(digest);
+        }
+    }
+
+    public static bool MatchesDigest(string? connectionTicket, string? expectedDigest)
+    {
+        if (!ContractValidation.IsConnectionTicketValid(connectionTicket)
+            || !ContractValidation.IsConnectionTicketValid(expectedDigest))
+        {
+            return false;
+        }
+
+        byte[] actual = Encoding.ASCII.GetBytes(ComputeDigest(connectionTicket!));
+        byte[] expected = Encoding.ASCII.GetBytes(expectedDigest!);
+        try
+        {
+            return CryptographicOperations.FixedTimeEquals(actual, expected);
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(actual);
+            CryptographicOperations.ZeroMemory(expected);
+        }
+    }
+
+    private static bool TryDecodeBase64Url(string? encoded, out byte[] bytes)
+    {
+        bytes = [];
+        if (encoded is null || encoded.Length != EncodedLength)
+        {
+            return false;
+        }
+
+        try
+        {
+            bytes = Convert.FromBase64String(
+                encoded.Replace('-', '+').Replace('_', '/') + "=");
+            return true;
+        }
+        catch (FormatException)
+        {
+            return false;
+        }
+    }
+
+    private static string EncodeBase64Url(byte[] value) =>
+        Convert.ToBase64String(value).TrimEnd('=').Replace('+', '-').Replace('/', '_');
+}

src/FinalFactory.Rendezvous.Server/Abuse/AbuseProtectionOptions.cs

@@ -0,0 +1,111 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace FinalFactory.Rendezvous.Server.Abuse;
+
+internal sealed class AbuseProtectionOptions
+{
+    public const string SectionName = "Rendezvous:AbuseProtection";
+
+    [Range(1, 60)]
+    public int WindowSeconds { get; set; } = 1;
+
+    [Range(1_000, 1_000_000)]
+    public int MaxTrackedKeys { get; set; } = 100_000;
+
+    [Range(0, 100_000)]
+    public int CriticalTrackedKeyReserve { get; set; } = 2_048;
+
+    [Range(1_000, 999_999)]
+    public int UdpTrackedKeyLimit { get; set; } = 70_000;
+
+    public string[] TrustedProxyAddresses { get; set; } = [];
+
+    public string[] OperatorAllowedAddresses { get; set; } = [];
+
+    [Range(1, 100_000)]
+    public int HealthGlobalRequestsPerWindow { get; set; } = 1_000;
+
+    [Range(1, 10_000)]
+    public int HealthGlobalConcurrency { get; set; } = 32;
+
+    [Range(1, 100_000)]
+    public int HealthIpPrefixRequestsPerWindow { get; set; } = 120;
+
+    [Range(1, 1_000)]
+    public int HealthIpPrefixConcurrency { get; set; } = 8;
+
+    [Range(1, 100_000)]
+    public int OperatorGlobalRequestsPerWindow { get; set; } = 1_000;
+
+    [Range(1, 10_000)]
+    public int OperatorGlobalConcurrency { get; set; } = 32;
+
+    [Range(1, 100_000)]
+    public int OperatorIpPrefixRequestsPerWindow { get; set; } = 120;
+
+    [Range(1, 1_000)]
+    public int OperatorIpPrefixConcurrency { get; set; } = 8;
+
+    [Range(1, 1_000_000)]
+    public int HttpGlobalRequestsPerWindow { get; set; } = 20_000;
+
+    [Range(1, 1_000_000)]
+    public int HttpOptionalRequestsPerWindow { get; set; } = 18_000;
+
+    [Range(1, 100_000)]
+    public int HttpIpPrefixRequestsPerWindow { get; set; } = 500;
+
+    [Range(1, 100_000)]
+    public int HttpOptionalIpPrefixRequestsPerWindow { get; set; } = 450;
+
+    [Range(1, 1_000_000)]
+    public int HttpOperationRequestsPerWindow { get; set; } = 5_000;
+
+    [Range(1, 1_000_000)]
+    public int HttpTenantRequestsPerWindow { get; set; } = 2_000;
+
+    [Range(1, 100_000)]
+    public int HttpPrincipalRequestsPerWindow { get; set; } = 500;
+
+    [Range(1, 100_000)]
+    public int HttpResourceRequestsPerWindow { get; set; } = 200;
+
+    [Range(1, 100_000)]
+    public int HttpGlobalConcurrency { get; set; } = 1_024;
+
+    [Range(1, 100_000)]
+    public int HttpOptionalConcurrency { get; set; } = 768;
+
+    [Range(1, 10_000)]
+    public int HttpIpPrefixConcurrency { get; set; } = 64;
+
+    [Range(1, 10_000)]
+    public int HttpOptionalIpPrefixConcurrency { get; set; } = 48;
+
+    [Range(1, 100_000)]
+    public int HttpOperationConcurrency { get; set; } = 256;
+
+    [Range(1, 100_000)]
+    public int HttpTenantConcurrency { get; set; } = 256;
+
+    [Range(1, 10_000)]
+    public int HttpPrincipalConcurrency { get; set; } = 32;
+
+    [Range(1, 10_000)]
+    public int HttpResourceConcurrency { get; set; } = 16;
+
+    [Range(1, 10_000_000)]
+    public int UdpGlobalDatagramsPerWindow { get; set; } = 100_000;
+
+    [Range(1, 1_000_000)]
+    public int UdpIpPrefixDatagramsPerWindow { get; set; } = 2_000;
+
+    [Range(1, 10_000_000)]
+    public int UdpOperationDatagramsPerWindow { get; set; } = 50_000;
+
+    [Range(1, 100_000)]
+    public int UdpCapabilityDatagramsPerWindow { get; set; } = 120;
+
+    [Range(1, 100_000)]
+    public int UdpResourceDatagramsPerWindow { get; set; } = 240;
+}

src/FinalFactory.Rendezvous.Server/Abuse/AbuseProtectionService.cs

@@ -0,0 +1,530 @@
+using System.Buffers;
+using System.Net;
+using System.Security.Cryptography;
+using System.Text;
+using FinalFactory.Rendezvous.Server.Observability;
+using Microsoft.Extensions.Options;
+
+namespace FinalFactory.Rendezvous.Server.Abuse;
+
+internal sealed class AbuseProtectionService
+{
+    private readonly AbuseProtectionOptions _options;
+    private readonly TimeProvider _timeProvider;
+    private readonly TrackerState _httpTracker;
+    private readonly TrackerState _udpTracker;
+    private readonly RendezvousTelemetry? _telemetry;
+    private readonly HashSet<string> _operatorAllowedAddresses;
+
+    public AbuseProtectionService(
+        IOptions<AbuseProtectionOptions> options,
+        TimeProvider? timeProvider = null,
+        RendezvousTelemetry? telemetry = null)
+    {
+        _options = options.Value;
+        _timeProvider = timeProvider ?? TimeProvider.System;
+        _telemetry = telemetry;
+        _operatorAllowedAddresses = options.Value.OperatorAllowedAddresses
+            .Select(static value => IPAddress.TryParse(value, out IPAddress? address)
+                ? NormalizeAddress(address).ToString()
+                : string.Empty)
+            .Where(static value => value.Length > 0)
+            .ToHashSet(StringComparer.Ordinal);
+        DateTimeOffset now = _timeProvider.GetUtcNow();
+        _httpTracker = new(now);
+        _udpTracker = new(now);
+    }
+
+    public bool TryAcquireHttpIngress(
+        IPAddress? remoteAddress,
+        string operation,
+        out AbuseLease? lease,
+        out int retryAfterSeconds)
+    {
+        string prefix = GetNetworkPrefix(remoteAddress);
+        List<RateDimension> rates =
+        [
+            new("http:rate:global", _options.HttpGlobalRequestsPerWindow),
+            new($"http:rate:ip:{prefix}", _options.HttpIpPrefixRequestsPerWindow),
+            new($"http:rate:operation:{operation}", _options.HttpOperationRequestsPerWindow),
+        ];
+        List<RateDimension> concurrency =
+        [
+            new("http:concurrency:global", _options.HttpGlobalConcurrency),
+            new($"http:concurrency:ip:{prefix}", _options.HttpIpPrefixConcurrency),
+            new($"http:concurrency:operation:{operation}", _options.HttpOperationConcurrency),
+        ];
+        if (!IsLeaseCriticalOperation(operation))
+        {
+            rates.Add(new("http:rate:optional", _options.HttpOptionalRequestsPerWindow));
+            rates.Add(new($"http:rate:optional-ip:{prefix}",
+                _options.HttpOptionalIpPrefixRequestsPerWindow));
+            concurrency.Add(new("http:concurrency:optional", _options.HttpOptionalConcurrency));
+            concurrency.Add(new($"http:concurrency:optional-ip:{prefix}",
+                _options.HttpOptionalIpPrefixConcurrency));
+        }
+
+        return TryAcquire(
+            [.. rates],
+            [.. concurrency],
+            TrackerDomain.Http,
+            IsLeaseCriticalOperation(operation),
+            out lease,
+            out retryAfterSeconds);
+    }
+
+    public bool TryAcquireHealthIngress(
+        IPAddress? remoteAddress,
+        out AbuseLease? lease,
+        out int retryAfterSeconds)
+    {
+        string prefix = GetNetworkPrefix(remoteAddress);
+        RateDimension[] rates =
+        [
+            new("health:rate:global", _options.HealthGlobalRequestsPerWindow),
+            new($"health:rate:ip:{prefix}", _options.HealthIpPrefixRequestsPerWindow),
+        ];
+        RateDimension[] concurrency =
+        [
+            new("health:concurrency:global", _options.HealthGlobalConcurrency),
+            new($"health:concurrency:ip:{prefix}", _options.HealthIpPrefixConcurrency),
+        ];
+        return TryAcquire(
+            rates,
+            concurrency,
+            TrackerDomain.Http,
+            true,
+            out lease,
+            out retryAfterSeconds);
+    }
+
+    public bool IsOperatorSourceAllowed(IPAddress? remoteAddress) =>
+        remoteAddress is not null
+        && _operatorAllowedAddresses.Contains(NormalizeAddress(remoteAddress).ToString());
+
+    public bool TryAcquireOperatorIngress(
+        IPAddress? remoteAddress,
+        out AbuseLease? lease,
+        out int retryAfterSeconds)
+    {
+        string prefix = GetNetworkPrefix(remoteAddress);
+        RateDimension[] rates =
+        [
+            new("operator:rate:global", _options.OperatorGlobalRequestsPerWindow),
+            new($"operator:rate:ip:{prefix}", _options.OperatorIpPrefixRequestsPerWindow),
+        ];
+        RateDimension[] concurrency =
+        [
+            new("operator:concurrency:global", _options.OperatorGlobalConcurrency),
+            new($"operator:concurrency:ip:{prefix}", _options.OperatorIpPrefixConcurrency),
+        ];
+        return TryAcquire(
+            rates,
+            concurrency,
+            TrackerDomain.Http,
+            true,
+            out lease,
+            out retryAfterSeconds);
+    }
+
+    public bool TryAcquireHttpIdentity(
+        string operation,
+        string? tenant,
+        string? principal,
+        string? resource,
+        out AbuseLease? lease,
+        out int retryAfterSeconds) => TryAcquireHttpIdentity(
+        operation,
+        null,
+        tenant,
+        principal,
+        resource,
+        out lease,
+        out retryAfterSeconds);
+
+    public bool TryAcquireHttpIdentity(
+        string operation,
+        IPAddress? remoteAddress,
+        string? tenant,
+        string? principal,
+        string? resource,
+        out AbuseLease? lease,
+        out int retryAfterSeconds)
+    {
+        string sourcePrefix = GetNetworkPrefix(remoteAddress);
+        List<RateDimension> rates = [];
+        List<RateDimension> concurrency = [];
+        AddDimension(rates, concurrency, "tenant", tenant,
+            _options.HttpTenantRequestsPerWindow, _options.HttpTenantConcurrency);
+        AddDimension(rates, concurrency, "principal", principal,
+            _options.HttpPrincipalRequestsPerWindow, _options.HttpPrincipalConcurrency);
+        AddDimension(rates, concurrency, "resource", resource,
+            _options.HttpResourceRequestsPerWindow, _options.HttpResourceConcurrency);
+        return TryAcquire(
+            [.. rates],
+            [.. concurrency],
+            TrackerDomain.Http,
+            IsLeaseCriticalOperation(operation),
+            out lease,
+            out retryAfterSeconds);
+
+        void AddDimension(
+            List<RateDimension> rateDimensions,
+            List<RateDimension> concurrencyDimensions,
+            string kind,
+            string? value,
+            int rateLimit,
+            int concurrencyLimit)
+        {
+            if (string.IsNullOrEmpty(value))
+            {
+                return;
+            }
+
+            if (kind == "resource")
+            {
+                string validationKey =
+                    $"http:source-resource:{operation}:{sourcePrefix}:{value}";
+                rateDimensions.Add(new($"{validationKey}:rate", rateLimit));
+                concurrencyDimensions.Add(new($"{validationKey}:concurrency", concurrencyLimit));
+            }
+
+            string key = kind == "resource"
+                ? $"http:resource-scoped:{operation}:{tenant ?? string.Empty}|{principal ?? string.Empty}:{value}"
+                : $"http:{kind}:{operation}:{value}";
+            rateDimensions.Add(new($"{key}:rate", rateLimit));
+            concurrencyDimensions.Add(new($"{key}:concurrency", concurrencyLimit));
+        }
+    }
+
+    public bool TryAcceptUdpIngress(IPAddress? remoteAddress, string operation)
+    {
+        string prefix = GetNetworkPrefix(remoteAddress);
+        RateDimension[] rates =
+        [
+            new("udp:rate:global", _options.UdpGlobalDatagramsPerWindow),
+            new($"udp:rate:ip:{prefix}", _options.UdpIpPrefixDatagramsPerWindow),
+            new($"udp:rate:operation:{operation}", _options.UdpOperationDatagramsPerWindow),
+        ];
+        return TryAcquire(
+                   rates,
+                   [],
+                   TrackerDomain.Udp,
+                   false,
+                   out AbuseLease? lease,
+                   out _)
+               && DisposeAccepted(lease);
+    }
+
+    public bool TryAcceptUdpIdentity(
+        string operation,
+        string capability,
+        string resource) => TryAcceptUdpIdentity(
+        operation,
+        null,
+        capability,
+        resource);
+
+    public bool TryAcceptUdpIdentity(
+        string operation,
+        IPAddress? remoteAddress,
+        string capability,
+        string resource)
+    {
+        string sourcePrefix = GetNetworkPrefix(remoteAddress);
+        string capabilityFingerprint = FingerprintSecret(capability);
+        RateDimension[] rates =
+        [
+            new($"udp:rate:capability:{operation}:{capabilityFingerprint}",
+                _options.UdpCapabilityDatagramsPerWindow),
+            new($"udp:rate:source-resource:{operation}:{sourcePrefix}:{resource}",
+                _options.UdpResourceDatagramsPerWindow),
+            new($"udp:rate:resource:{operation}:{capabilityFingerprint}:{resource}",
+                _options.UdpResourceDatagramsPerWindow),
+        ];
+        return TryAcquire(
+                   rates,
+                   [],
+                   TrackerDomain.Udp,
+                   false,
+                   out AbuseLease? lease,
+                   out _)
+               && DisposeAccepted(lease);
+    }
+
+    public static string FingerprintSecret(string secret)
+    {
+        int byteCount = Encoding.UTF8.GetByteCount(secret);
+        byte[]? rented = null;
+        Span<byte> encoded = byteCount <= 1_024
+            ? stackalloc byte[byteCount]
+            : (rented = ArrayPool<byte>.Shared.Rent(byteCount)).AsSpan(0, byteCount);
+        Span<byte> digest = stackalloc byte[32];
+        try
+        {
+            _ = Encoding.UTF8.GetBytes(secret, encoded);
+            _ = SHA256.HashData(encoded, digest);
+            return Convert.ToHexString(digest[..12]);
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(encoded);
+            CryptographicOperations.ZeroMemory(digest);
+            if (rented is not null)
+            {
+                ArrayPool<byte>.Shared.Return(rented);
+            }
+        }
+    }
+
+    internal int TrackedKeyCount
+    {
+        get
+        {
+            int http;
+            int udp;
+            lock (_httpTracker.Gate)
+            {
+                http = _httpTracker.WindowCounts.Count + _httpTracker.ConcurrencyCounts.Count;
+            }
+
+            lock (_udpTracker.Gate)
+            {
+                udp = _udpTracker.WindowCounts.Count + _udpTracker.ConcurrencyCounts.Count;
+            }
+
+            return http + udp;
+        }
+    }
+
+    private bool TryAcquire(
+        ReadOnlySpan<RateDimension> rates,
+        ReadOnlySpan<RateDimension> concurrency,
+        TrackerDomain domain,
+        bool canUseCriticalReserve,
+        out AbuseLease? lease,
+        out int retryAfterSeconds)
+    {
+        TrackerState tracker = domain == TrackerDomain.Udp ? _udpTracker : _httpTracker;
+        bool accepted;
+        lock (tracker.Gate)
+        {
+            accepted = TryAcquireLocked(
+                tracker,
+                rates,
+                concurrency,
+                domain,
+                canUseCriticalReserve,
+                out lease,
+                out retryAfterSeconds);
+        }
+
+        if (!accepted)
+        {
+            _telemetry?.RecordLimiterDrop(
+                domain == TrackerDomain.Udp ? "udp" : "http",
+                "rate-or-concurrency");
+        }
+
+        return accepted;
+    }
+
+    private bool TryAcquireLocked(
+        TrackerState tracker,
+        ReadOnlySpan<RateDimension> rates,
+        ReadOnlySpan<RateDimension> concurrency,
+        TrackerDomain domain,
+        bool canUseCriticalReserve,
+        out AbuseLease? lease,
+        out int retryAfterSeconds)
+    {
+        DateTimeOffset now = _timeProvider.GetUtcNow();
+        TimeSpan window = TimeSpan.FromSeconds(_options.WindowSeconds);
+        if (now - tracker.WindowStartedAt >= window || now < tracker.WindowStartedAt)
+        {
+            tracker.WindowCounts.Clear();
+            tracker.WindowStartedAt = now;
+        }
+
+        retryAfterSeconds = Math.Max(
+            1,
+            (int)Math.Ceiling((window - (now - tracker.WindowStartedAt)).TotalSeconds));
+        int stagedNewKeys = 0;
+        int partitionLimit = domain == TrackerDomain.Udp
+            ? _options.UdpTrackedKeyLimit
+            : _options.MaxTrackedKeys - _options.UdpTrackedKeyLimit;
+        int maxTrackedKeys = domain == TrackerDomain.Udp || canUseCriticalReserve
+            ? partitionLimit
+            : partitionLimit - _options.CriticalTrackedKeyReserve;
+        if (!CanAcquireAll(
+                tracker,
+                tracker.WindowCounts,
+                rates,
+                maxTrackedKeys,
+                ref stagedNewKeys)
+            || !CanAcquireAll(
+                tracker,
+                tracker.ConcurrencyCounts,
+                concurrency,
+                maxTrackedKeys,
+                ref stagedNewKeys))
+        {
+            lease = null;
+            return false;
+        }
+
+        foreach (RateDimension dimension in rates)
+        {
+            tracker.WindowCounts[dimension.Key] =
+                tracker.WindowCounts.GetValueOrDefault(dimension.Key) + 1;
+        }
+
+        if (concurrency.IsEmpty)
+        {
+            lease = null;
+            return true;
+        }
+
+        string[] acquiredConcurrency = new string[concurrency.Length];
+        for (int index = 0; index < concurrency.Length; index++)
+        {
+            RateDimension dimension = concurrency[index];
+            tracker.ConcurrencyCounts[dimension.Key] =
+                tracker.ConcurrencyCounts.GetValueOrDefault(dimension.Key) + 1;
+            acquiredConcurrency[index] = dimension.Key;
+        }
+
+        lease = new AbuseLease(this, tracker, acquiredConcurrency);
+        return true;
+    }
+
+    private static bool CanAcquireAll(
+        TrackerState tracker,
+        Dictionary<string, int> counts,
+        ReadOnlySpan<RateDimension> dimensions,
+        int maxTrackedKeys,
+        ref int stagedNewKeys)
+    {
+        foreach (RateDimension dimension in dimensions)
+        {
+            if (counts.TryGetValue(dimension.Key, out int current))
+            {
+                if (current >= dimension.Limit)
+                {
+                    return false;
+                }
+
+                continue;
+            }
+
+            stagedNewKeys++;
+            if (tracker.WindowCounts.Count + tracker.ConcurrencyCounts.Count + stagedNewKeys
+                > maxTrackedKeys)
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private static void Release(TrackerState tracker, string[] keys)
+    {
+        lock (tracker.Gate)
+        {
+            foreach (string key in keys)
+            {
+                if (!tracker.ConcurrencyCounts.TryGetValue(key, out int current))
+                {
+                    continue;
+                }
+
+                if (current <= 1)
+                {
+                    tracker.ConcurrencyCounts.Remove(key);
+                }
+                else
+                {
+                    tracker.ConcurrencyCounts[key] = current - 1;
+                }
+            }
+        }
+    }
+
+    private static bool DisposeAccepted(AbuseLease? lease)
+    {
+        lease?.Dispose();
+        return true;
+    }
+
+    private static bool IsLeaseCriticalOperation(string operation) => operation is
+        "RenewSessionLease" or "UpdateSession" or "DeleteSession";
+
+    private static string GetNetworkPrefix(IPAddress? address)
+    {
+        if (address is null)
+        {
+            return "unknown";
+        }
+
+        IPAddress normalized = address.IsIPv4MappedToIPv6 ? address.MapToIPv4() : address;
+        byte[] bytes = normalized.GetAddressBytes();
+        if (bytes.Length == 4)
+        {
+            bytes[3] = 0;
+            return $"4:{Convert.ToHexString(bytes)}:24";
+        }
+
+        if (bytes.Length == 16)
+        {
+            Array.Clear(bytes, 7, 9);
+            return $"6:{Convert.ToHexString(bytes)}:56";
+        }
+
+        return "unknown";
+    }
+
+    private static IPAddress NormalizeAddress(IPAddress address) =>
+        address.IsIPv4MappedToIPv6 ? address.MapToIPv4() : address;
+
+    private readonly record struct RateDimension(string Key, int Limit);
+
+    private enum TrackerDomain
+    {
+        Http,
+        Udp,
+    }
+
+    internal sealed class TrackerState(DateTimeOffset windowStartedAt)
+    {
+        public object Gate { get; } = new();
+        public Dictionary<string, int> WindowCounts { get; } = new(StringComparer.Ordinal);
+        public Dictionary<string, int> ConcurrencyCounts { get; } = new(StringComparer.Ordinal);
+        public DateTimeOffset WindowStartedAt { get; set; } = windowStartedAt;
+    }
+
+    internal sealed class AbuseLease : IDisposable
+    {
+        private AbuseProtectionService? _owner;
+        private readonly TrackerState _tracker;
+        private readonly string[] _keys;
+
+        internal AbuseLease(
+            AbuseProtectionService owner,
+            TrackerState tracker,
+            string[] keys)
+        {
+            _owner = owner;
+            _tracker = tracker;
+            _keys = keys;
+        }
+
+        public void Dispose()
+        {
+            if (Interlocked.Exchange(ref _owner, null) is not null)
+            {
+                Release(_tracker, _keys);
+            }
+        }
+    }
+}

src/FinalFactory.Rendezvous.Server/Abuse/HttpAbuseProtectionMiddleware.cs

@@ -0,0 +1,135 @@
+using FinalFactory.Rendezvous.Contracts;
+using Microsoft.AspNetCore.Http.Features;
+
+namespace FinalFactory.Rendezvous.Server.Abuse;
+
+internal sealed class HttpAbuseProtectionMiddleware(
+    RequestDelegate next,
+    AbuseProtectionService protection)
+{
+    public async Task InvokeAsync(HttpContext context)
+    {
+        IHttpMaxRequestBodySizeFeature? bodySize =
+            context.Features.Get<IHttpMaxRequestBodySizeFeature>();
+        if (bodySize is { IsReadOnly: false })
+        {
+            bodySize.MaxRequestBodySize = ContractLimits.HttpRequestMaxBytes;
+        }
+
+        string operation = context.GetEndpoint()?.Metadata.GetMetadata<IEndpointNameMetadata>()
+            ?.EndpointName ?? "Unmatched";
+        bool healthEndpoint = operation is "GetLiveness" or "GetReadiness";
+        bool operatorEndpoint = operation is
+            "GetOperatorStatus"
+            or "RevokeOperatorListing"
+            or "RevokeOperatorPrincipal"
+            or "RevokeOperatorSigningKey"
+            or "BeginOperatorDrain";
+        if (operatorEndpoint
+            && !protection.IsOperatorSourceAllowed(context.Connection.RemoteIpAddress))
+        {
+            bool deniedSourceAdmitted = protection.TryAcquireHttpIngress(
+                context.Connection.RemoteIpAddress,
+                "Unmatched",
+                out AbuseProtectionService.AbuseLease? deniedSourceLease,
+                out int deniedRetryAfterSeconds);
+            using (deniedSourceLease)
+            {
+                if (!deniedSourceAdmitted)
+                {
+                    context.Response.Headers.RetryAfter = deniedRetryAfterSeconds.ToString(
+                        System.Globalization.CultureInfo.InvariantCulture);
+                    await WriteErrorAsync(
+                        context,
+                        StatusCodes.Status429TooManyRequests,
+                        RendezvousErrorCode.RateLimited,
+                        "The request rate limit was exceeded.",
+                        deniedRetryAfterSeconds).ConfigureAwait(false);
+                    return;
+                }
+
+                await WriteErrorAsync(
+                    context,
+                    StatusCodes.Status404NotFound,
+                    RendezvousErrorCode.NotFound,
+                    "The requested resource was not found.").ConfigureAwait(false);
+            }
+
+            return;
+        }
+
+        AbuseProtectionService.AbuseLease? lease;
+        int retryAfterSeconds;
+        bool acquired;
+        if (healthEndpoint)
+        {
+            acquired = protection.TryAcquireHealthIngress(
+                context.Connection.RemoteIpAddress,
+                out lease,
+                out retryAfterSeconds);
+        }
+        else if (operatorEndpoint)
+        {
+            acquired = protection.TryAcquireOperatorIngress(
+                context.Connection.RemoteIpAddress,
+                out lease,
+                out retryAfterSeconds);
+        }
+        else
+        {
+            acquired = protection.TryAcquireHttpIngress(
+                context.Connection.RemoteIpAddress,
+                operation,
+                out lease,
+                out retryAfterSeconds);
+        }
+
+        if (!acquired)
+        {
+            context.Response.Headers.RetryAfter = retryAfterSeconds.ToString(
+                System.Globalization.CultureInfo.InvariantCulture);
+            await WriteErrorAsync(
+                context,
+                StatusCodes.Status429TooManyRequests,
+                RendezvousErrorCode.RateLimited,
+                "The request rate limit was exceeded.",
+                retryAfterSeconds).ConfigureAwait(false);
+            return;
+        }
+
+        using (lease)
+        {
+            if (context.Request.ContentLength > ContractLimits.HttpRequestMaxBytes)
+            {
+                await WriteErrorAsync(
+                    context,
+                    StatusCodes.Status413PayloadTooLarge,
+                    RendezvousErrorCode.InvalidRequest,
+                    "The request body exceeds the supported size.").ConfigureAwait(false);
+                return;
+            }
+
+            await next(context).ConfigureAwait(false);
+        }
+    }
+
+    private static Task WriteErrorAsync(
+        HttpContext context,
+        int status,
+        RendezvousErrorCode code,
+        string message,
+        int? retryAfterSeconds = null)
+    {
+        context.Response.StatusCode = status;
+        return context.Response.WriteAsJsonAsync(
+            new ApiError
+            {
+                Code = code,
+                Message = message,
+                RetryAfterSeconds = retryAfterSeconds,
+            },
+            ContractJson.Options,
+            contentType: "application/json",
+            cancellationToken: context.RequestAborted);
+    }
+}

src/FinalFactory.Rendezvous.Server/Abuse/TrustedProxyForwarding.cs

@@ -0,0 +1,24 @@
+using System.Net;
+using Microsoft.AspNetCore.HttpOverrides;
+
+namespace FinalFactory.Rendezvous.Server.Abuse;
+
+internal static class TrustedProxyForwarding
+{
+    public static bool IsEnabled(AbuseProtectionOptions options) =>
+        options.TrustedProxyAddresses is { Length: > 0 };
+
+    public static void Configure(
+        ForwardedHeadersOptions forwarded,
+        AbuseProtectionOptions abuse)
+    {
+        forwarded.ForwardedHeaders = ForwardedHeaders.XForwardedFor;
+        forwarded.ForwardLimit = 1;
+        forwarded.KnownProxies.Clear();
+        forwarded.KnownIPNetworks.Clear();
+        foreach (string address in abuse.TrustedProxyAddresses ?? [])
+        {
+            forwarded.KnownProxies.Add(IPAddress.Parse(address));
+        }
+    }
+}

src/FinalFactory.Rendezvous.Server/Browser/SessionBrowserService.cs

@@ -153,5 +153,6 @@ internal sealed class SessionBrowserService(
             static item => item.Key,
             static item => item.Value,
             StringComparer.Ordinal),
+        DedicatedFallback = StoredListing.CopyEndpoint(stored.Definition.DedicatedFallback),
     };
 }

src/FinalFactory.Rendezvous.Server/ConnectionOutcomes/ConnectionOutcomeService.cs

@@ -0,0 +1,141 @@
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Observability;
+using FinalFactory.Rendezvous.Server.Sessions;
+using FinalFactory.Rendezvous.Server.State;
+
+namespace FinalFactory.Rendezvous.Server.ConnectionOutcomes;
+
+internal sealed record ConnectionOutcomeServiceResult(
+    RendezvousErrorCode Error,
+    ReportConnectionOutcomeResponse? Value = null)
+{
+    public bool Succeeded => Error == RendezvousErrorCode.None;
+}
+
+internal sealed class ConnectionOutcomeMetrics
+{
+    private readonly object _gate = new();
+    private readonly Dictionary<(ConnectionOutcomeKind, ConnectionElapsedBucket), long> _counts = [];
+    private readonly RendezvousTelemetry? _telemetry;
+
+    public ConnectionOutcomeMetrics(RendezvousTelemetry? telemetry = null) =>
+        _telemetry = telemetry;
+
+    internal void Record(ConnectionOutcomeKind outcome, ConnectionElapsedBucket elapsedBucket)
+    {
+        lock (_gate)
+        {
+            (ConnectionOutcomeKind, ConnectionElapsedBucket) key = (outcome, elapsedBucket);
+            _counts.TryGetValue(key, out long count);
+            _counts[key] = count + 1;
+        }
+
+        _telemetry?.RecordConnectionOutcome(outcome.ToString(), elapsedBucket.ToString());
+    }
+
+    internal long GetCount(ConnectionOutcomeKind outcome, ConnectionElapsedBucket elapsedBucket)
+    {
+        lock (_gate)
+        {
+            return _counts.GetValueOrDefault((outcome, elapsedBucket));
+        }
+    }
+}
+
+internal sealed class ConnectionOutcomeService(
+    IEphemeralRendezvousStore store,
+    ISessionCapabilityService capabilities,
+    ConnectionOutcomeMetrics metrics)
+{
+    internal ConnectionOutcomeServiceResult Report(
+        JoinAttemptId attemptId,
+        string? clientPunchCapability,
+        ReportConnectionOutcomeRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+        RendezvousErrorCode version = ContractValidation.ValidateContractVersion(
+            request.ContractVersion);
+        if (version != RendezvousErrorCode.None)
+        {
+            return new(version);
+        }
+
+        if (attemptId.Value == Guid.Empty
+            || !ContractValidation.IsCapabilityValid(clientPunchCapability)
+            || !TryNormalizeReport(request, out ConnectionOutcomeKind outcome, out ConnectionElapsedBucket elapsedBucket)
+            || !capabilities.TryFingerprint(
+                clientPunchCapability,
+                out SecretFingerprint capabilityFingerprint))
+        {
+            return new(RendezvousErrorCode.InvalidRequest);
+        }
+
+        StoreResult<StoredConnectionOutcome> reported = store.ReportConnectionOutcome(new(
+            attemptId,
+            capabilityFingerprint,
+            outcome,
+            elapsedBucket), cancellationToken);
+        if (!reported.Succeeded)
+        {
+            return new(reported.Code.ToContractError());
+        }
+
+        if (!reported.IsIdempotentReplay)
+        {
+            metrics.Record(outcome, elapsedBucket);
+        }
+
+        return new(RendezvousErrorCode.None, new ReportConnectionOutcomeResponse
+        {
+            Accepted = true,
+            IsDuplicate = reported.IsIdempotentReplay,
+        });
+    }
+
+    private static bool TryNormalizeReport(
+        ReportConnectionOutcomeRequest request,
+        out ConnectionOutcomeKind outcome,
+        out ConnectionElapsedBucket elapsedBucket)
+    {
+        outcome = request.Outcome switch
+        {
+            ConnectionOutcomeKind.TimedOut => ConnectionOutcomeKind.PunchTimedOut,
+            ConnectionOutcomeKind.StaleHost => ConnectionOutcomeKind.NoHostPresence,
+            ConnectionOutcomeKind.TransportFailed => ConnectionOutcomeKind.TransportError,
+            _ => request.Outcome,
+        };
+        if (!ContractValidation.IsReportableConnectionOutcome(request.Outcome))
+        {
+            elapsedBucket = default;
+            return false;
+        }
+
+        if (Enum.IsDefined(request.ElapsedBucket))
+        {
+            elapsedBucket = request.ElapsedBucket;
+            return true;
+        }
+
+#pragma warning disable CS0618 // Frozen v1 compatibility input; never retained at exact precision.
+        if (request.ElapsedBucket == default && request.ElapsedMilliseconds >= 0)
+        {
+            elapsedBucket = BucketElapsedMilliseconds(request.ElapsedMilliseconds);
+            return true;
+        }
+#pragma warning restore CS0618
+
+        elapsedBucket = default;
+        return false;
+    }
+
+    private static ConnectionElapsedBucket BucketElapsedMilliseconds(int elapsedMilliseconds) =>
+        elapsedMilliseconds switch
+        {
+            < 1_000 => ConnectionElapsedBucket.UnderOneSecond,
+            < 5_000 => ConnectionElapsedBucket.OneToFiveSeconds,
+            < 15_000 => ConnectionElapsedBucket.FiveToFifteenSeconds,
+            < 30_000 => ConnectionElapsedBucket.FifteenToThirtySeconds,
+            _ => ConnectionElapsedBucket.ThirtySecondsOrMore,
+        };
+}

src/FinalFactory.Rendezvous.Server/Deployment/DeploymentOptions.cs

@@ -0,0 +1,235 @@
+using System.ComponentModel.DataAnnotations;
+using System.Net;
+using FinalFactory.Rendezvous.Server.Abuse;
+
+namespace FinalFactory.Rendezvous.Server.Deployment;
+
+internal sealed record DeploymentOptions
+{
+    public const string SectionName = "Rendezvous:Deployment";
+
+    [Required]
+    public string PublicHttpBaseUrl { get; init; } = string.Empty;
+
+    [Required]
+    public string PublicUdpHost { get; init; } = string.Empty;
+
+    [Range(1, 65_535)]
+    public int PublicUdpPort { get; init; } = 9050;
+
+    [Range(1, 30)]
+    public int DrainDeadlineSeconds { get; init; } = 30;
+
+    [Range(0, 5)]
+    public int MinimumDrainSeconds { get; init; } = 1;
+
+    public bool SingleActiveInstance { get; init; } = true;
+
+    public bool AllowPrivatePublicEndpoints { get; init; }
+
+    public IReadOnlyList<string> ValidateProduction(
+        AbuseProtectionOptions abuseProtection,
+        string? allowedHosts)
+    {
+        List<string> errors = [];
+        if (!SingleActiveInstance)
+        {
+            errors.Add("Rendezvous:Deployment:SingleActiveInstance must be true because ephemeral state is not shared between replicas.");
+        }
+
+        if (MinimumDrainSeconds >= DrainDeadlineSeconds)
+        {
+            errors.Add("Rendezvous:Deployment:MinimumDrainSeconds must be less than DrainDeadlineSeconds.");
+        }
+
+        if (DrainDeadlineSeconds is < 1 or > 30)
+        {
+            errors.Add("Rendezvous:Deployment:DrainDeadlineSeconds must be between 1 and 30.");
+        }
+
+        if (MinimumDrainSeconds is < 0 or > 5)
+        {
+            errors.Add("Rendezvous:Deployment:MinimumDrainSeconds must be between 0 and 5.");
+        }
+
+        if (PublicUdpPort is < 1 or > 65_535)
+        {
+            errors.Add("Rendezvous:Deployment:PublicUdpPort must be between 1 and 65535.");
+        }
+
+        ValidateHttpEndpoint(errors);
+        ValidateUdpEndpoint(errors);
+        ValidateAllowedHosts(errors, allowedHosts, PublicHttpBaseUrl);
+
+        if (abuseProtection.TrustedProxyAddresses is not { Length: > 0 })
+        {
+            errors.Add(
+                "Rendezvous:AbuseProtection:TrustedProxyAddresses must list the exact TLS proxy addresses; forwarded headers are rejected without this trust boundary.");
+        }
+
+        return errors;
+    }
+
+    private void ValidateHttpEndpoint(List<string> errors)
+    {
+        if (!Uri.TryCreate(PublicHttpBaseUrl, UriKind.Absolute, out Uri? endpoint)
+            || !string.Equals(endpoint.Scheme, Uri.UriSchemeHttps, StringComparison.Ordinal)
+            || !string.IsNullOrEmpty(endpoint.UserInfo)
+            || !string.IsNullOrEmpty(endpoint.Query)
+            || !string.IsNullOrEmpty(endpoint.Fragment)
+            || endpoint.AbsolutePath != "/")
+        {
+            errors.Add(
+                "Rendezvous:Deployment:PublicHttpBaseUrl must be an absolute HTTPS origin with no credentials, path, query, or fragment (for example, https://rendezvous.your-company.tld/).");
+            return;
+        }
+
+        if (!AllowPrivatePublicEndpoints && !IsPublicHost(endpoint.Host))
+        {
+            errors.Add(
+                "Rendezvous:Deployment:PublicHttpBaseUrl must use a public DNS name or address; set AllowPrivatePublicEndpoints=true only for an isolated deployment smoke test.");
+        }
+    }
+
+    private void ValidateUdpEndpoint(List<string> errors)
+    {
+        if (string.IsNullOrWhiteSpace(PublicUdpHost)
+            || PublicUdpHost.Contains("//", StringComparison.Ordinal)
+            || PublicUdpHost.Contains(':', StringComparison.Ordinal) && !IPAddress.TryParse(PublicUdpHost, out _)
+            || Uri.CheckHostName(PublicUdpHost) == UriHostNameType.Unknown)
+        {
+            errors.Add(
+                "Rendezvous:Deployment:PublicUdpHost must contain only the advertised DNS name or IP address; configure the port separately.");
+            return;
+        }
+
+        if (!AllowPrivatePublicEndpoints && !IsPublicHost(PublicUdpHost))
+        {
+            errors.Add(
+                "Rendezvous:Deployment:PublicUdpHost must use a public DNS name or address; set AllowPrivatePublicEndpoints=true only for an isolated deployment smoke test.");
+        }
+    }
+
+    private static void ValidateAllowedHosts(
+        List<string> errors,
+        string? allowedHosts,
+        string publicHttpBaseUrl)
+    {
+        string[] hosts = (allowedHosts ?? string.Empty).Split(
+            ';',
+            StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+        if (hosts.Length == 0 || hosts.Any(static host => host is "*" or "+"))
+        {
+            errors.Add(
+                "AllowedHosts must explicitly list the public HTTP host in production; wildcard or empty host filtering is unsafe.");
+            return;
+        }
+
+        if (Uri.TryCreate(publicHttpBaseUrl, UriKind.Absolute, out Uri? endpoint)
+            && !hosts.Contains(endpoint.Host, StringComparer.OrdinalIgnoreCase))
+        {
+            errors.Add(
+                "AllowedHosts must contain the exact host advertised by Rendezvous:Deployment:PublicHttpBaseUrl.");
+        }
+    }
+
+    private static bool IsPublicHost(string host)
+    {
+        if (!IPAddress.TryParse(host, out IPAddress? address))
+        {
+            return Uri.CheckHostName(host) == UriHostNameType.Dns
+                && host.Contains('.', StringComparison.Ordinal)
+                && !IsReservedDnsName(host);
+        }
+
+        return IsGloballyRoutableUnicast(address);
+    }
+
+    private static bool IsReservedDnsName(string host)
+    {
+        string normalized = host.TrimEnd('.');
+        string[] reservedSuffixes =
+        [
+            "localhost",
+            "local",
+            "invalid",
+            "test",
+            "example",
+            "example.com",
+            "example.net",
+            "example.org",
+            "home.arpa",
+            "alt",
+            "onion",
+        ];
+        return reservedSuffixes.Any(suffix =>
+            string.Equals(normalized, suffix, StringComparison.OrdinalIgnoreCase)
+            || normalized.EndsWith($".{suffix}", StringComparison.OrdinalIgnoreCase));
+    }
+
+    private static bool IsGloballyRoutableUnicast(IPAddress address)
+    {
+        if (address.IsIPv4MappedToIPv6)
+        {
+            address = address.MapToIPv4();
+        }
+
+        byte[] bytes = address.GetAddressBytes();
+        if (address.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
+        {
+            return !(bytes[0] is 0 or 10 or 127
+                || bytes[0] == 100 && bytes[1] is >= 64 and <= 127
+                || bytes[0] == 169 && bytes[1] == 254
+                || bytes[0] == 172 && bytes[1] is >= 16 and <= 31
+                || bytes[0] == 192
+                    && (bytes[1] == 0 && bytes[2] is 0 or 2
+                        || bytes[1] == 88 && bytes[2] == 99
+                        || bytes[1] == 168)
+                || bytes[0] == 198
+                    && (bytes[1] is 18 or 19
+                        || bytes[1] == 51 && bytes[2] == 100)
+                || bytes[0] == 203 && bytes[1] == 0 && bytes[2] == 113
+                || bytes[0] >= 224);
+        }
+
+        return address.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6
+            && !IPAddress.IsLoopback(address)
+            && !address.Equals(IPAddress.IPv6Any)
+            && !address.IsIPv6LinkLocal
+            && !address.IsIPv6SiteLocal
+            && !address.IsIPv6Multicast
+            && (bytes[0] & 0xe0) == 0x20
+            && !HasPrefix(bytes, [0x20, 0x01, 0x00], 23)
+            && !HasPrefix(bytes, [0x20, 0x01, 0x0d, 0xb8], 32)
+            && !HasPrefix(bytes, [0x20, 0x02], 16)
+            && !HasPrefix(bytes, [0x3f, 0xff, 0x00], 20);
+    }
+
+    private static bool HasPrefix(byte[] address, byte[] prefix, int bitCount)
+    {
+        int fullBytes = bitCount / 8;
+        for (int index = 0; index < fullBytes; index++)
+        {
+            if (address[index] != prefix[index])
+            {
+                return false;
+            }
+        }
+
+        int remainingBits = bitCount % 8;
+        if (remainingBits == 0)
+        {
+            return true;
+        }
+
+        int mask = 0xff << (8 - remainingBits);
+        return (address[fullBytes] & mask) == (prefix[fullBytes] & mask);
+    }
+}
+
+internal sealed class DeploymentConfigurationException(IReadOnlyList<string> errors)
+    : InvalidOperationException(
+        "Production deployment configuration is invalid:" + Environment.NewLine
+        + string.Join(Environment.NewLine, errors.Select(static error => $"- {error}")))
+{
+}

src/FinalFactory.Rendezvous.Server/Deployment/GracefulDrainService.cs

@@ -0,0 +1,98 @@
+using System.Diagnostics;
+using FinalFactory.Rendezvous.Server.State;
+using Microsoft.Extensions.Options;
+
+namespace FinalFactory.Rendezvous.Server.Deployment;
+
+internal sealed partial class GracefulDrainService : IHostedService, IDisposable
+{
+    private static readonly TimeSpan PollInterval = TimeSpan.FromMilliseconds(50);
+    private readonly InMemoryEphemeralRendezvousStore _store;
+    private readonly IHostApplicationLifetime _lifetime;
+    private readonly DeploymentOptions _options;
+    private readonly ILogger<GracefulDrainService> _logger;
+    private readonly object _gate = new();
+    private CancellationTokenRegistration _stoppingRegistration;
+    private Task? _drainTask;
+
+    public GracefulDrainService(
+        InMemoryEphemeralRendezvousStore store,
+        IHostApplicationLifetime lifetime,
+        IOptions<DeploymentOptions> options,
+        ILogger<GracefulDrainService> logger)
+    {
+        _store = store;
+        _lifetime = lifetime;
+        _options = options.Value;
+        _logger = logger;
+    }
+
+    public Task StartAsync(CancellationToken cancellationToken)
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        _stoppingRegistration = _lifetime.ApplicationStopping.Register(
+            () => EnsureDrainAsync().GetAwaiter().GetResult());
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken)
+    {
+        // ApplicationStopping callbacks run before hosted services and listeners
+        // stop. StopAsync is the idempotent fallback for directly driven hosts.
+        _ = cancellationToken;
+        return EnsureDrainAsync();
+    }
+
+    public void Dispose() => _stoppingRegistration.Dispose();
+
+    private Task EnsureDrainAsync()
+    {
+        lock (_gate)
+        {
+            return _drainTask ??= DrainAsync();
+        }
+    }
+
+    private async Task DrainAsync()
+    {
+        _store.BeginDrain(CancellationToken.None);
+        TimeSpan deadline = TimeSpan.FromSeconds(_options.DrainDeadlineSeconds);
+        TimeSpan minimum = TimeSpan.FromSeconds(_options.MinimumDrainSeconds);
+        long startedAt = Stopwatch.GetTimestamp();
+        LogDrainStarted(_logger, _options.DrainDeadlineSeconds);
+        try
+        {
+            while (Stopwatch.GetElapsedTime(startedAt) < deadline)
+            {
+                TimeSpan elapsed = Stopwatch.GetElapsedTime(startedAt);
+                if (elapsed >= minimum && _store.GetActiveJoinAttemptCountForDrain() == 0)
+                {
+                    break;
+                }
+
+                TimeSpan remaining = deadline - elapsed;
+                await Task.Delay(
+                    remaining < PollInterval ? remaining : PollInterval,
+                    CancellationToken.None).ConfigureAwait(false);
+            }
+        }
+        finally
+        {
+            _store.MarkUnavailable();
+            double elapsedMilliseconds = Stopwatch.GetElapsedTime(startedAt).TotalMilliseconds;
+            LogDrainFinished(_logger, elapsedMilliseconds);
+        }
+    }
+
+    [LoggerMessage(
+        EventId = 1,
+        Level = LogLevel.Information,
+        Message = "Graceful drain started with a {DrainDeadlineSeconds}-second deadline")]
+    private static partial void LogDrainStarted(ILogger logger, int drainDeadlineSeconds);
+
+    [LoggerMessage(
+        EventId = 2,
+        Level = LogLevel.Information,
+        Message = "Graceful drain finished after {ElapsedMilliseconds:F0} ms; ephemeral state was cleared")]
+    private static partial void LogDrainFinished(ILogger logger, double elapsedMilliseconds);
+}

src/FinalFactory.Rendezvous.Server/Http/ContractEndpoints.cs

@@ -1,6 +1,8 @@
 using System.Net;
 using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.Browser;
+using FinalFactory.Rendezvous.Server.ConnectionOutcomes;
 using FinalFactory.Rendezvous.Server.JoinAttempts;
 using FinalFactory.Rendezvous.Server.Provisioning;
 using FinalFactory.Rendezvous.Server.Sessions;
@@ -11,8 +13,6 @@ namespace FinalFactory.Rendezvous.Server.Http;
 
 internal static class ContractEndpoints
 {
-    private const int NotImplementedStatus = StatusCodes.Status501NotImplemented;
-
     public static IEndpointRouteBuilder MapRendezvousContractEndpoints(
         this IEndpointRouteBuilder endpoints)
     {
@@ -21,6 +21,7 @@ internal static class ContractEndpoints
             .Accepts<RegisterSessionRequest>("application/json")
             .Produces<RegisterSessionResponse>(StatusCodes.Status201Created)
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
             .Produces<ApiError>(StatusCodes.Status401Unauthorized)
             .Produces<ApiError>(StatusCodes.Status403Forbidden)
             .Produces<ApiError>(StatusCodes.Status409Conflict)
@@ -32,45 +33,54 @@ internal static class ContractEndpoints
             .Accepts<RenewLeaseRequest>("application/json")
             .Produces<RenewLeaseResponse>()
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
             .Produces<ApiError>(StatusCodes.Status401Unauthorized)
             .Produces<ApiError>(StatusCodes.Status403Forbidden)
             .Produces<ApiError>(StatusCodes.Status404NotFound)
             .Produces<ApiError>(StatusCodes.Status409Conflict)
             .Produces<ApiError>(StatusCodes.Status410Gone)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("RenewSessionLease");
         sessions.MapPut("/{listingId}", UpdateSession)
             .Accepts<UpdateSessionRequest>("application/json")
             .Produces(StatusCodes.Status204NoContent)
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
             .Produces<ApiError>(StatusCodes.Status401Unauthorized)
             .Produces<ApiError>(StatusCodes.Status403Forbidden)
             .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("UpdateSession");
         sessions.MapDelete("/{listingId}", DeleteSession)
             .Accepts<DeleteSessionRequest>("application/json")
             .Produces(StatusCodes.Status204NoContent)
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
             .Produces<ApiError>(StatusCodes.Status401Unauthorized)
             .Produces<ApiError>(StatusCodes.Status403Forbidden)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("DeleteSession");
         sessions.MapGet("/", BrowseSessions)
             .Produces<BrowseSessionsResponse>()
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("BrowseSessions");
         sessions.MapGet("/{listingId}", GetSession)
             .Produces<GetSessionResponse>()
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
             .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("GetSession");
         sessions.MapGet("/{listingId}/join-attempts", BrowseHostJoinAttempts)
             .Produces<BrowseHostJoinAttemptsResponse>()
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
             .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("BrowseHostJoinAttempts");
 
@@ -81,8 +91,10 @@ internal static class ContractEndpoints
             .Accepts<CreateJoinAttemptRequest>("application/json")
             .Produces<CreateJoinAttemptResponse>(StatusCodes.Status201Created)
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
             .Produces<ApiError>(StatusCodes.Status404NotFound)
             .Produces<ApiError>(StatusCodes.Status409Conflict)
+            .Produces<ApiError>(StatusCodes.Status410Gone)
             .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("CreateJoinAttempt");
@@ -90,12 +102,18 @@ internal static class ContractEndpoints
             .Produces(StatusCodes.Status204NoContent)
             .Produces<ApiError>(StatusCodes.Status400BadRequest)
             .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
             .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("CancelJoinAttempt");
         attempts.MapPost("/{attemptId}/outcome", ReportConnectionOutcome)
             .Accepts<ReportConnectionOutcomeRequest>("application/json")
             .Produces<ReportConnectionOutcomeResponse>()
-            .Produces<ApiError>(StatusCodes.Status501NotImplemented)
+            .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
+            .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status409Conflict)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
             .WithName("ReportConnectionOutcome");
 
         return endpoints;
@@ -106,6 +124,7 @@ internal static class ContractEndpoints
         [FromHeader(Name = "Authorization")] string? authorizationHeader,
         [FromServices] PrincipalCredentialService credentials,
         [FromServices] SessionLeaseService sessions,
+        [FromServices] AbuseProtectionService abuseProtection,
         [FromServices] IWallClock clock,
         HttpContext httpContext,
         CancellationToken cancellationToken)
@@ -119,13 +138,29 @@ internal static class ContractEndpoints
             return AuthenticationRequired(httpContext);
         }
 
-        SessionServiceResult<RegisterSessionResponse> result = sessions.Register(
-            principal!,
-            request,
-            cancellationToken);
-        return result.Succeeded && result.Value is not null
-            ? Results.Created($"/v1/sessions/{result.Value.ListingId}", result.Value)
-            : Error(result.Error);
+        IPublisherPrincipal publisher = (IPublisherPrincipal)principal!;
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "RegisterSession",
+                Tenant(publisher.GameId, publisher.EnvironmentId),
+                publisher.Subject,
+                null,
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            SessionServiceResult<RegisterSessionResponse> result = sessions.Register(
+                principal!,
+                request,
+                cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Created($"/v1/sessions/{result.Value.ListingId}", result.Value)
+                : Error(result.Error);
+        }
     }
 
     private static IResult RenewLease(
@@ -134,6 +169,7 @@ internal static class ContractEndpoints
         [FromHeader(Name = "Authorization")] string? authorizationHeader,
         [FromServices] PrincipalCredentialService credentials,
         [FromServices] SessionLeaseService sessions,
+        [FromServices] AbuseProtectionService abuseProtection,
         [FromServices] IWallClock clock,
         HttpContext httpContext,
         CancellationToken cancellationToken)
@@ -147,14 +183,30 @@ internal static class ContractEndpoints
             return AuthenticationRequired(httpContext);
         }
 
-        SessionServiceResult<RenewLeaseResponse> result = sessions.Renew(
-            principal!,
-            listingId,
-            request,
-            cancellationToken);
-        return result.Succeeded && result.Value is not null
-            ? Results.Ok(result.Value)
-            : Error(result.Error);
+        IPublisherPrincipal publisher = (IPublisherPrincipal)principal!;
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "RenewSessionLease",
+                Tenant(publisher.GameId, publisher.EnvironmentId),
+                publisher.Subject,
+                listingId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            SessionServiceResult<RenewLeaseResponse> result = sessions.Renew(
+                principal!,
+                listingId,
+                request,
+                cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Ok(result.Value)
+                : Error(result.Error);
+        }
     }
 
     private static IResult UpdateSession(
@@ -163,6 +215,7 @@ internal static class ContractEndpoints
         [FromHeader(Name = "Authorization")] string? authorizationHeader,
         [FromServices] PrincipalCredentialService credentials,
         [FromServices] SessionLeaseService sessions,
+        [FromServices] AbuseProtectionService abuseProtection,
         [FromServices] IWallClock clock,
         HttpContext httpContext,
         CancellationToken cancellationToken)
@@ -176,12 +229,28 @@ internal static class ContractEndpoints
             return AuthenticationRequired(httpContext);
         }
 
-        SessionServiceResult<bool> result = sessions.Update(
-            principal!,
-            listingId,
-            request,
-            cancellationToken);
-        return result.Succeeded ? Results.NoContent() : Error(result.Error);
+        IPublisherPrincipal publisher = (IPublisherPrincipal)principal!;
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "UpdateSession",
+                Tenant(publisher.GameId, publisher.EnvironmentId),
+                publisher.Subject,
+                listingId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            SessionServiceResult<bool> result = sessions.Update(
+                principal!,
+                listingId,
+                request,
+                cancellationToken);
+            return result.Succeeded ? Results.NoContent() : Error(result.Error);
+        }
     }
 
     private static IResult DeleteSession(
@@ -190,6 +259,7 @@ internal static class ContractEndpoints
         [FromHeader(Name = "Authorization")] string? authorizationHeader,
         [FromServices] PrincipalCredentialService credentials,
         [FromServices] SessionLeaseService sessions,
+        [FromServices] AbuseProtectionService abuseProtection,
         [FromServices] IWallClock clock,
         HttpContext httpContext,
         CancellationToken cancellationToken)
@@ -203,12 +273,28 @@ internal static class ContractEndpoints
             return AuthenticationRequired(httpContext);
         }
 
-        SessionServiceResult<bool> result = sessions.Delete(
-            principal!,
-            listingId,
-            request,
-            cancellationToken);
-        return result.Succeeded ? Results.NoContent() : Error(result.Error);
+        IPublisherPrincipal publisher = (IPublisherPrincipal)principal!;
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "DeleteSession",
+                Tenant(publisher.GameId, publisher.EnvironmentId),
+                publisher.Subject,
+                listingId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            SessionServiceResult<bool> result = sessions.Delete(
+                principal!,
+                listingId,
+                request,
+                cancellationToken);
+            return result.Succeeded ? Results.NoContent() : Error(result.Error);
+        }
     }
 
     private static IResult BrowseSessions(
@@ -221,6 +307,8 @@ internal static class ContractEndpoints
         [FromQuery] bool? excludeFull,
         [FromQuery] string? cursor,
         [FromServices] SessionBrowserService browser,
+        [FromServices] AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
         CancellationToken cancellationToken)
     {
         if (!GameId.TryParse(gameId, out GameId parsedGameId)
@@ -230,20 +318,35 @@ internal static class ContractEndpoints
             return Error(RendezvousErrorCode.InvalidRequest);
         }
 
-        BrowserServiceResult<BrowseSessionsResponse> result = browser.Browse(new()
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "BrowseSessions",
+                Tenant(parsedGameId, parsedEnvironmentId),
+                null,
+                null,
+                out AbuseProtectionService.AbuseLease? abuseLease))
         {
-            ContractVersion = contractVersion,
-            GameId = parsedGameId,
-            EnvironmentId = parsedEnvironmentId,
-            ProtocolVersion = protocolVersion,
-            RegionId = regionId is null ? null : new RegionId(regionId),
-            PageSize = pageSize ?? ContractLimits.BrowserPageMaxItems,
-            ExcludeFull = excludeFull ?? false,
-            Cursor = cursor,
-        }, cancellationToken);
-        return result.Succeeded && result.Value is not null
-            ? Results.Ok(result.Value)
-            : Error(result.Error);
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            BrowserServiceResult<BrowseSessionsResponse> result = browser.Browse(new()
+            {
+                ContractVersion = contractVersion,
+                GameId = parsedGameId,
+                EnvironmentId = parsedEnvironmentId,
+                ProtocolVersion = protocolVersion,
+                RegionId = regionId is null ? null : new RegionId(regionId),
+                PageSize = pageSize ?? ContractLimits.BrowserPageMaxItems,
+                ExcludeFull = excludeFull ?? false,
+                Cursor = cursor,
+            }, cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Ok(result.Value)
+                : Error(result.Error);
+        }
     }
 
     private static IResult GetSession(
@@ -253,6 +356,8 @@ internal static class ContractEndpoints
         [FromQuery] string environmentId,
         [FromQuery] uint protocolVersion,
         [FromServices] SessionBrowserService browser,
+        [FromServices] AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
         CancellationToken cancellationToken)
     {
         if (ContractValidation.ValidateContractVersion(contractVersion) != RendezvousErrorCode.None)
@@ -266,15 +371,30 @@ internal static class ContractEndpoints
             return Error(RendezvousErrorCode.InvalidRequest);
         }
 
-        BrowserServiceResult<GetSessionResponse> result = browser.Get(
-            listingId,
-            parsedGameId,
-            parsedEnvironmentId,
-            protocolVersion,
-            cancellationToken);
-        return result.Succeeded && result.Value is not null
-            ? Results.Ok(result.Value)
-            : Error(result.Error);
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "GetSession",
+                Tenant(parsedGameId, parsedEnvironmentId),
+                null,
+                listingId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            BrowserServiceResult<GetSessionResponse> result = browser.Get(
+                listingId,
+                parsedGameId,
+                parsedEnvironmentId,
+                protocolVersion,
+                cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Ok(result.Value)
+                : Error(result.Error);
+        }
     }
 
     private static IResult BrowseHostJoinAttempts(
@@ -284,23 +404,41 @@ internal static class ContractEndpoints
         [FromQuery] int? pageSize,
         [FromQuery] string? cursor,
         [FromServices] JoinAttemptService attempts,
+        [FromServices] AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
         CancellationToken cancellationToken)
     {
-        JoinAttemptServiceResult<BrowseHostJoinAttemptsResponse> result = attempts.BrowseForHost(
-            listingId,
-            contractVersion,
-            leaseToken,
-            pageSize ?? ContractLimits.BrowserPageMaxItems,
-            cursor,
-            cancellationToken);
-        return result.Succeeded && result.Value is not null
-            ? Results.Ok(result.Value)
-            : Error(result.Error);
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "BrowseHostJoinAttempts",
+                null,
+                AbuseProtectionService.FingerprintSecret(leaseToken ?? string.Empty),
+                listingId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            JoinAttemptServiceResult<BrowseHostJoinAttemptsResponse> result = attempts.BrowseForHost(
+                listingId,
+                contractVersion,
+                leaseToken,
+                pageSize ?? ContractLimits.BrowserPageMaxItems,
+                cursor,
+                cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Ok(result.Value)
+                : Error(result.Error);
+        }
     }
 
     private static IResult CreateJoinAttempt(
         [FromBody] CreateJoinAttemptRequest request,
         [FromServices] JoinAttemptService attempts,
+        [FromServices] AbuseProtectionService abuseProtection,
         HttpContext httpContext,
         CancellationToken cancellationToken)
     {
@@ -310,40 +448,93 @@ internal static class ContractEndpoints
         }
 
         string clientSubject = attempts.CreateAnonymousClientSubject(remoteAddress);
-        JoinAttemptServiceResult<CreateJoinAttemptResponse> result = attempts.Create(
-            clientSubject,
-            request,
-            cancellationToken);
-        return result.Succeeded && result.Value is not null
-            ? Results.Created($"/v1/join-attempts/{result.Value.AttemptId}", result.Value)
-            : Error(result.Error);
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "CreateJoinAttempt",
+                Tenant(request.GameId, request.EnvironmentId),
+                clientSubject,
+                request.ListingId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            JoinAttemptServiceResult<CreateJoinAttemptResponse> result = attempts.Create(
+                clientSubject,
+                request,
+                cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Created($"/v1/join-attempts/{result.Value.AttemptId}", result.Value)
+                : Error(result.Error);
+        }
     }
 
     private static IResult CancelJoinAttempt(
         JoinAttemptId attemptId,
         [FromHeader(Name = "X-Rendezvous-Client-Punch-Capability")] string clientPunchCapability,
         [FromServices] JoinAttemptService attempts,
+        [FromServices] AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
         CancellationToken cancellationToken)
     {
-        JoinAttemptServiceResult<bool> result = attempts.Cancel(
-            attemptId,
-            clientPunchCapability,
-            cancellationToken);
-        return result.Succeeded ? Results.NoContent() : Error(result.Error);
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "CancelJoinAttempt",
+                null,
+                AbuseProtectionService.FingerprintSecret(clientPunchCapability ?? string.Empty),
+                attemptId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
+        {
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            JoinAttemptServiceResult<bool> result = attempts.Cancel(
+                attemptId,
+                clientPunchCapability,
+                cancellationToken);
+            return result.Succeeded ? Results.NoContent() : Error(result.Error);
+        }
     }
 
     private static IResult ReportConnectionOutcome(
         JoinAttemptId attemptId,
-        [FromBody] ReportConnectionOutcomeRequest request) => NotImplemented();
-
-    private static IResult NotImplemented() => Results.Json(
-        new ApiError
+        [FromHeader(Name = "X-Rendezvous-Client-Punch-Capability")] string clientPunchCapability,
+        [FromBody] ReportConnectionOutcomeRequest request,
+        [FromServices] ConnectionOutcomeService outcomes,
+        [FromServices] AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
+        CancellationToken cancellationToken)
+    {
+        if (!TryAcquireIdentity(
+                abuseProtection,
+                httpContext,
+                "ReportConnectionOutcome",
+                null,
+                AbuseProtectionService.FingerprintSecret(clientPunchCapability ?? string.Empty),
+                attemptId.ToString(),
+                out AbuseProtectionService.AbuseLease? abuseLease))
         {
-            Code = RendezvousErrorCode.ServiceUnavailable,
-            Message = "The v1 contract is reserved; implementation is tracked by subsequent issues.",
-        },
-        ContractJson.Options,
-        statusCode: NotImplementedStatus);
+            return RateLimited(httpContext);
+        }
+
+        using (abuseLease)
+        {
+            ConnectionOutcomeServiceResult result = outcomes.Report(
+                attemptId,
+                clientPunchCapability,
+                request,
+                cancellationToken);
+            return result.Succeeded && result.Value is not null
+                ? Results.Ok(result.Value)
+                : Error(result.Error);
+        }
+    }
 
     private static bool TryAuthenticatePublisher(
         string? authorizationHeader,
@@ -370,11 +561,41 @@ internal static class ContractEndpoints
         return true;
     }
 
-    private static IResult Error(RendezvousErrorCode code) => Results.Json(
+    private static bool TryAcquireIdentity(
+        AbuseProtectionService abuseProtection,
+        HttpContext httpContext,
+        string operation,
+        string? tenant,
+        string? principal,
+        string? resource,
+        out AbuseProtectionService.AbuseLease? lease)
+    {
+        if (abuseProtection.TryAcquireHttpIdentity(
+                operation,
+                httpContext.Connection.RemoteIpAddress,
+                tenant,
+                principal,
+                resource,
+                out lease,
+                out int retryAfterSeconds))
+        {
+            return true;
+        }
+
+        httpContext.Response.Headers.RetryAfter = retryAfterSeconds.ToString(
+            System.Globalization.CultureInfo.InvariantCulture);
+        return false;
+    }
+
+    private static string Tenant(GameId gameId, EnvironmentId environmentId) =>
+        $"{gameId.Value}/{environmentId.Value}";
+
+    private static IResult Error(RendezvousErrorCode code, int? retryAfterSeconds = null) => Results.Json(
         new ApiError
         {
             Code = code,
             Message = ErrorMessage(code),
+            RetryAfterSeconds = retryAfterSeconds,
         },
         ContractJson.Options,
         statusCode: ErrorStatus(code));
@@ -385,13 +606,27 @@ internal static class ContractEndpoints
         return Error(RendezvousErrorCode.AuthenticationRequired);
     }
 
+    private static IResult RateLimited(HttpContext context)
+    {
+        int? retryAfterSeconds = int.TryParse(
+            context.Response.Headers.RetryAfter,
+            System.Globalization.NumberStyles.None,
+            System.Globalization.CultureInfo.InvariantCulture,
+            out int parsed)
+            ? Math.Clamp(parsed, 1, 60)
+            : null;
+        return Error(RendezvousErrorCode.RateLimited, retryAfterSeconds);
+    }
+
     private static int ErrorStatus(RendezvousErrorCode code) => code switch
     {
         RendezvousErrorCode.AuthenticationRequired => StatusCodes.Status401Unauthorized,
         RendezvousErrorCode.Forbidden => StatusCodes.Status403Forbidden,
-        RendezvousErrorCode.NotFound or RendezvousErrorCode.StaleHost => StatusCodes.Status404NotFound,
-        RendezvousErrorCode.Conflict or RendezvousErrorCode.ReplayRejected => StatusCodes.Status409Conflict,
-        RendezvousErrorCode.Expired => StatusCodes.Status410Gone,
+        RendezvousErrorCode.NotFound => StatusCodes.Status404NotFound,
+        RendezvousErrorCode.Conflict
+            or RendezvousErrorCode.IncompatibleProtocol
+            or RendezvousErrorCode.ReplayRejected => StatusCodes.Status409Conflict,
+        RendezvousErrorCode.Expired or RendezvousErrorCode.StaleHost => StatusCodes.Status410Gone,
         RendezvousErrorCode.RateLimited or RendezvousErrorCode.CapacityExceeded =>
             StatusCodes.Status429TooManyRequests,
         RendezvousErrorCode.ServiceUnavailable => StatusCodes.Status503ServiceUnavailable,
@@ -406,7 +641,9 @@ internal static class ContractEndpoints
         RendezvousErrorCode.NotFound => "The session was not found or is not owned by this publisher.",
         RendezvousErrorCode.Conflict => "The session changed concurrently; retry with current state.",
         RendezvousErrorCode.Expired => "The session lease has expired.",
+        RendezvousErrorCode.StaleHost => "The session has no fresh host presence.",
         RendezvousErrorCode.IncompatibleProtocol => "The gameplay protocol is not enabled for this game.",
+        RendezvousErrorCode.RateLimited => "The request rate limit was exceeded.",
         RendezvousErrorCode.CapacityExceeded => "The configured session capacity is currently exhausted.",
         RendezvousErrorCode.ServiceUnavailable => "Session state is temporarily unavailable.",
         RendezvousErrorCode.UnsupportedContractVersion => "The requested contract version is not supported.",

src/FinalFactory.Rendezvous.Server/Http/RendezvousExceptionHandler.cs

@@ -4,7 +4,8 @@ using Microsoft.AspNetCore.Diagnostics;
 
 namespace FinalFactory.Rendezvous.Server.Http;
 
-internal sealed class RendezvousExceptionHandler : IExceptionHandler
+internal sealed partial class RendezvousExceptionHandler(
+    ILogger<RendezvousExceptionHandler> logger) : IExceptionHandler
 {
     public async ValueTask<bool> TryHandleAsync(
         HttpContext httpContext,
@@ -17,21 +18,46 @@ internal sealed class RendezvousExceptionHandler : IExceptionHandler
         }
 
         bool invalidRequest = exception is BadHttpRequestException or JsonException;
-        httpContext.Response.StatusCode = invalidRequest
-            ? StatusCodes.Status400BadRequest
-            : StatusCodes.Status500InternalServerError;
+        bool payloadTooLarge = exception is BadHttpRequestException
+        {
+            StatusCode: StatusCodes.Status413PayloadTooLarge,
+        };
+        httpContext.Response.StatusCode = payloadTooLarge
+            ? StatusCodes.Status413PayloadTooLarge
+            : invalidRequest
+                ? StatusCodes.Status400BadRequest
+                : StatusCodes.Status500InternalServerError;
+        LogRequestFailure(
+            logger,
+            payloadTooLarge ? "payload-too-large" : invalidRequest ? "invalid-request" : "internal-error",
+            httpContext.Response.StatusCode,
+            httpContext.Response.Headers["X-Rendezvous-Correlation-ID"].ToString() is { Length: > 0 } value
+                ? value
+                : "unavailable");
         await httpContext.Response.WriteAsJsonAsync(
             new ApiError
             {
                 Code = invalidRequest
                     ? RendezvousErrorCode.InvalidRequest
                     : RendezvousErrorCode.InternalError,
-                Message = invalidRequest
-                    ? "The request body, route, or query value is invalid."
-                    : "The service could not complete the request.",
+                Message = payloadTooLarge
+                    ? "The request body exceeds the supported size."
+                    : invalidRequest
+                        ? "The request body, route, or query value is invalid."
+                        : "The service could not complete the request.",
             },
             ContractJson.Options,
             cancellationToken).ConfigureAwait(false);
         return true;
     }
+
+    [LoggerMessage(
+        EventId = 200,
+        Level = LogLevel.Warning,
+        Message = "Request failed with {FailureKind} and HTTP status {StatusCode}; correlation {CorrelationId}")]
+    private static partial void LogRequestFailure(
+        ILogger logger,
+        string failureKind,
+        int statusCode,
+        string correlationId);
 }

src/FinalFactory.Rendezvous.Server/JoinAttempts/JoinAttemptService.cs

@@ -66,7 +66,15 @@ internal sealed class JoinAttemptService(
         string derivationSalt = capabilities.CreateDerivationSalt();
         string hostCapability = Derive("join-host-punch", clientSubject, request, requestFingerprint, derivationSalt);
         string clientCapability = Derive("join-client-punch", clientSubject, request, requestFingerprint, derivationSalt);
-        string connectionTicket = Derive("connection-ticket", clientSubject, request, requestFingerprint, derivationSalt);
+        JoinAttemptId attemptId = new(capabilities.DeriveGuid(
+            "join-attempt-id",
+            clientSubject,
+            request.IdempotencyKey,
+            requestFingerprint,
+            derivationSalt));
+        string connectionTicket = NatIntroductionTokenCodec.Encode(
+            attemptId,
+            Derive("connection-ticket", clientSubject, request, requestFingerprint, derivationSalt));
         if (!CredentialLengthsAreValid(hostCapability, clientCapability, connectionTicket)
             || !capabilities.TryFingerprint(hostCapability, out SecretFingerprint hostFingerprint)
             || !capabilities.TryFingerprint(clientCapability, out SecretFingerprint clientFingerprint)
@@ -75,12 +83,6 @@ internal sealed class JoinAttemptService(
             throw new InvalidOperationException("Derived join credentials violated their contract invariants.");
         }
 
-        JoinAttemptId attemptId = new(capabilities.DeriveGuid(
-            "join-attempt-id",
-            clientSubject,
-            request.IdempotencyKey,
-            requestFingerprint,
-            derivationSalt));
         MediationHandle mediationHandle = new(capabilities.DeriveGuid(
             "join-mediation-handle",
             clientSubject,
@@ -126,7 +128,10 @@ internal sealed class JoinAttemptService(
             AttemptId = persisted.AttemptId,
             MediationHandle = persisted.MediationHandle,
             ClientPunchCapability = clientCapability,
+            ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
+                CreateConnectionTicket(persisted)),
             ExpiresAt = persisted.ExpiresAt,
+            DedicatedFallback = StoredListing.CopyEndpoint(persisted.DedicatedFallback),
         });
     }
 
@@ -203,7 +208,7 @@ internal sealed class JoinAttemptService(
         StoredJoinAttempt attempt)
     {
         ArgumentNullException.ThrowIfNull(attempt);
-        if (!attempt.IntroductionConsumed)
+        if (!attempt.IntroductionConsumed || attempt.IsCancelled)
         {
             return new(RendezvousErrorCode.Conflict);
         }
@@ -213,12 +218,7 @@ internal sealed class JoinAttemptService(
             return new(RendezvousErrorCode.Expired);
         }
 
-        string ticket = Derive(
-            "connection-ticket",
-            attempt.ClientSubject,
-            attempt.IdempotencyKey,
-            attempt.RequestFingerprint,
-            attempt.CapabilityDerivationSalt);
+        string ticket = CreateConnectionTicket(attempt);
         if (!ContractValidation.IsConnectionTicketValid(ticket)
             || !capabilities.TryFingerprint(ticket, out SecretFingerprint fingerprint)
             || fingerprint != attempt.ConnectionTicketFingerprint)
@@ -249,10 +249,23 @@ internal sealed class JoinAttemptService(
             AttemptId = attempt.AttemptId,
             MediationHandle = attempt.MediationHandle,
             HostPunchCapability = capability,
+            ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
+                CreateConnectionTicket(attempt)),
+            IsCancelled = attempt.IsCancelled,
             ExpiresAt = attempt.ExpiresAt,
         };
     }
 
+    private string CreateConnectionTicket(StoredJoinAttempt attempt) =>
+        NatIntroductionTokenCodec.Encode(
+            attempt.AttemptId,
+            Derive(
+                "connection-ticket",
+                attempt.ClientSubject,
+                attempt.IdempotencyKey,
+                attempt.RequestFingerprint,
+                attempt.CapabilityDerivationSalt));
+
     private static RendezvousErrorCode ValidateCreate(CreateJoinAttemptRequest request)
     {
         RendezvousErrorCode version = ContractValidation.ValidateContractVersion(request.ContractVersion);

src/FinalFactory.Rendezvous.Server/Observability/AuditOptions.cs

@@ -0,0 +1,14 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace FinalFactory.Rendezvous.Server.Observability;
+
+internal sealed class AuditOptions
+{
+    public const string SectionName = "Rendezvous:Audit";
+
+    [Range(100, 100_000)]
+    public int MaxEntries { get; set; } = 10_000;
+
+    [Range(1, 30)]
+    public int RetentionDays { get; set; } = 30;
+}

src/FinalFactory.Rendezvous.Server/Observability/AuditTrail.cs

@@ -0,0 +1,134 @@
+using System.Security.Cryptography;
+using System.Text;
+using Microsoft.Extensions.Options;
+
+namespace FinalFactory.Rendezvous.Server.Observability;
+
+internal sealed partial class AuditTrail
+{
+    private readonly object _gate = new();
+    private readonly LinkedList<AuditEntry> _entries = [];
+    private readonly AuditOptions _options;
+    private readonly TimeProvider _timeProvider;
+    private readonly ILogger<AuditTrail> _logger;
+    private readonly RendezvousTelemetry _telemetry;
+
+    public AuditTrail(
+        IOptions<AuditOptions> options,
+        ILogger<AuditTrail> logger,
+        RendezvousTelemetry telemetry,
+        TimeProvider? timeProvider = null)
+    {
+        _options = options.Value;
+        _logger = logger;
+        _telemetry = telemetry;
+        _timeProvider = timeProvider ?? TimeProvider.System;
+    }
+
+    public void Record(
+        string actorSubject,
+        string action,
+        string result,
+        string targetKind,
+        string targetIdentifier,
+        string correlationId)
+    {
+        DateTimeOffset now = _timeProvider.GetUtcNow();
+        AuditEntry entry = new(
+            now,
+            Fingerprint(actorSubject),
+            action,
+            result,
+            targetKind,
+            Fingerprint(targetIdentifier),
+            correlationId);
+        lock (_gate)
+        {
+            PurgeExpired(now);
+
+            while (_entries.Count >= _options.MaxEntries)
+            {
+                _entries.RemoveFirst();
+            }
+
+            _entries.AddLast(entry);
+        }
+
+        _telemetry.RecordAudit(action, result);
+        LogOperatorAction(
+            _logger,
+            entry.Timestamp,
+            entry.ActorFingerprint,
+            action,
+            result,
+            targetKind,
+            entry.TargetFingerprint,
+            correlationId);
+    }
+
+    public IReadOnlyDictionary<string, long> GetAggregateCounts()
+    {
+        lock (_gate)
+        {
+            PurgeExpired(_timeProvider.GetUtcNow());
+            return _entries
+                .GroupBy(static entry => $"{entry.Action}:{entry.Result}", StringComparer.Ordinal)
+                .ToDictionary(
+                    static group => group.Key,
+                    static group => (long)group.Count(),
+                    StringComparer.Ordinal);
+        }
+    }
+
+    internal IReadOnlyList<AuditEntry> GetEntriesForTests()
+    {
+        lock (_gate)
+        {
+            PurgeExpired(_timeProvider.GetUtcNow());
+            return _entries.ToArray();
+        }
+    }
+
+    private void PurgeExpired(DateTimeOffset now)
+    {
+        DateTimeOffset oldest = now.AddDays(-_options.RetentionDays);
+        while (_entries.First is { Value.Timestamp: var timestamp }
+               && timestamp < oldest)
+        {
+            _entries.RemoveFirst();
+        }
+    }
+
+    private static string Fingerprint(string value)
+    {
+        byte[] digest = SHA256.HashData(Encoding.UTF8.GetBytes(value));
+        return Convert.ToHexString(digest.AsSpan(0, 12));
+    }
+
+    [LoggerMessage(
+        EventId = 100,
+        Level = LogLevel.Information,
+        Message = "Operator audit at {Timestamp}: actor {ActorFingerprint} action {Action} completed with {Result} for {TargetKind} target {TargetFingerprint}; correlation {CorrelationId}")]
+    private static partial void LogOperatorAction(
+        ILogger logger,
+        DateTimeOffset timestamp,
+        string actorFingerprint,
+        string action,
+        string result,
+        string targetKind,
+        string targetFingerprint,
+        string correlationId);
+}
+
+internal sealed record AuditEntry(
+    DateTimeOffset Timestamp,
+    string ActorFingerprint,
+    string Action,
+    string Result,
+    string TargetKind,
+    string TargetFingerprint,
+    string CorrelationId)
+{
+    public override string ToString() =>
+        $"[AuditEntry {Action}/{Result}; actor and target fingerprinted]";
+}

src/FinalFactory.Rendezvous.Server/Observability/HealthEndpoints.cs

@@ -0,0 +1,30 @@
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.Server.Observability;
+
+internal static class HealthEndpoints
+{
+    public static IEndpointRouteBuilder MapRendezvousHealthEndpoints(
+        this IEndpointRouteBuilder endpoints)
+    {
+        endpoints.MapGet(
+                "/health/live",
+                static () => Results.Ok(new HealthResponse { Status = "live" }))
+            .Produces<HealthResponse>()
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .WithName("GetLiveness")
+            .WithTags("Health");
+        endpoints.MapGet(
+                "/health/ready",
+                static (RendezvousReadiness readiness) =>
+                    !readiness.GetSnapshot().IsReady
+                        ? Results.StatusCode(StatusCodes.Status503ServiceUnavailable)
+                        : Results.Ok(new HealthResponse { Status = "ready" }))
+            .Produces<HealthResponse>()
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .Produces(StatusCodes.Status503ServiceUnavailable)
+            .WithName("GetReadiness")
+            .WithTags("Health");
+        return endpoints;
+    }
+}

src/FinalFactory.Rendezvous.Server/Observability/RendezvousReadiness.cs

@@ -0,0 +1,41 @@
+using FinalFactory.Rendezvous.Server.Provisioning;
+using FinalFactory.Rendezvous.Server.State;
+using FinalFactory.Rendezvous.Server.Transport;
+using Microsoft.Extensions.Options;
+
+namespace FinalFactory.Rendezvous.Server.Observability;
+
+internal sealed class RendezvousReadiness(
+    UdpMediatorService mediator,
+    ProvisioningReadiness provisioning,
+    IEphemeralRendezvousStore state,
+    IOptions<UdpMediatorOptions> udpOptions)
+{
+    public ReadinessSnapshot GetSnapshot()
+    {
+        bool ipv6Required = !string.IsNullOrWhiteSpace(udpOptions.Value.Ipv6ListenAddress);
+        return new ReadinessSnapshot(
+            HttpListenerReady: true,
+            UdpIpv4ListenerReady: mediator.LocalEndpoint is not null,
+            UdpIpv6ListenerReady: !ipv6Required || mediator.LocalIpv6Endpoint is not null,
+            ProvisioningReady: provisioning.IsReady,
+            StoreAvailable: state.IsAvailable,
+            Draining: state.IsDraining);
+    }
+}
+
+internal sealed record ReadinessSnapshot(
+    bool HttpListenerReady,
+    bool UdpIpv4ListenerReady,
+    bool UdpIpv6ListenerReady,
+    bool ProvisioningReady,
+    bool StoreAvailable,
+    bool Draining)
+{
+    public bool IsReady => HttpListenerReady
+        && UdpIpv4ListenerReady
+        && UdpIpv6ListenerReady
+        && ProvisioningReady
+        && StoreAvailable
+        && !Draining;
+}

src/FinalFactory.Rendezvous.Server/Observability/RendezvousTelemetry.cs

@@ -0,0 +1,126 @@
+using System.Diagnostics;
+using System.Diagnostics.Metrics;
+using FinalFactory.Rendezvous.Server.State;
+
+namespace FinalFactory.Rendezvous.Server.Observability;
+
+internal sealed class RendezvousTelemetry : IDisposable
+{
+    public const string MeterName = "FinalFactory.Rendezvous";
+    public const string ActivitySourceName = "FinalFactory.Rendezvous.Server";
+
+    private readonly InMemoryEphemeralRendezvousStore _store;
+    private readonly Meter _meter = new(MeterName, "1.0.0");
+    private readonly ActivitySource _activities = new(ActivitySourceName, "1.0.0");
+    private readonly Counter<long> _httpRequests;
+    private readonly Histogram<double> _httpDuration;
+    private readonly Counter<long> _udpResults;
+    private readonly Histogram<double> _udpDuration;
+    private readonly Counter<long> _limiterDrops;
+    private readonly Counter<long> _auditEvents;
+    private readonly Counter<long> _connectionOutcomes;
+    private readonly Counter<long> _operatorAuthentication;
+    private readonly Histogram<double> _pairingLatency;
+
+    public RendezvousTelemetry(InMemoryEphemeralRendezvousStore store)
+    {
+        _store = store;
+        _httpRequests = _meter.CreateCounter<long>("rendezvous.http.requests");
+        _httpDuration = _meter.CreateHistogram<double>(
+            "rendezvous.http.duration",
+            "ms");
+        _udpResults = _meter.CreateCounter<long>("rendezvous.udp.results");
+        _udpDuration = _meter.CreateHistogram<double>(
+            "rendezvous.udp.duration",
+            "ms");
+        _limiterDrops = _meter.CreateCounter<long>("rendezvous.limiter.drops");
+        _auditEvents = _meter.CreateCounter<long>("rendezvous.audit.events");
+        _connectionOutcomes = _meter.CreateCounter<long>("rendezvous.connection.outcomes");
+        _operatorAuthentication = _meter.CreateCounter<long>("rendezvous.operator.authentication");
+        _pairingLatency = _meter.CreateHistogram<double>(
+            "rendezvous.pairing.latency",
+            "ms");
+        _meter.CreateObservableGauge(
+            "rendezvous.store.active_listings",
+            () => _store.GetMetricsSnapshot().ActiveListings);
+        _meter.CreateObservableGauge(
+            "rendezvous.store.active_leases",
+            () => _store.GetMetricsSnapshot().ActiveListings);
+        _meter.CreateObservableGauge(
+            "rendezvous.store.active_attempts",
+            () => _store.GetMetricsSnapshot().ActiveJoinAttempts);
+        _meter.CreateObservableGauge(
+            "rendezvous.queue.depth",
+            () => _store.GetMetricsSnapshot().ActiveJoinAttempts);
+        _meter.CreateObservableGauge(
+            "rendezvous.store.replay_markers",
+            () => _store.GetMetricsSnapshot().ReplayMarkers);
+        _meter.CreateObservableGauge(
+            "rendezvous.store.available",
+            () => _store.GetMetricsSnapshot().IsAvailable ? 1 : 0);
+        _meter.CreateObservableCounter(
+            "rendezvous.store.expiry_churn",
+            () => _store.GetMetricsSnapshot().ExpiryChurn);
+    }
+
+    public Activity? StartActivity(string name, ActivityKind kind = ActivityKind.Internal) =>
+        _activities.StartActivity(name, kind);
+
+    public void RecordHttp(string operation, int statusCode, double elapsedMilliseconds)
+    {
+        TagList tags = new()
+        {
+            { "operation", operation },
+            { "status_code", statusCode },
+        };
+        _httpRequests.Add(1, tags);
+        _httpDuration.Record(elapsedMilliseconds, tags);
+    }
+
+    public void RecordUdp(string operation, string result, double elapsedMilliseconds)
+    {
+        TagList tags = new()
+        {
+            { "operation", operation },
+            { "result", result },
+        };
+        _udpResults.Add(1, tags);
+        _udpDuration.Record(elapsedMilliseconds, tags);
+    }
+
+    public void RecordLimiterDrop(string transport, string partition) =>
+        _limiterDrops.Add(1, new TagList
+        {
+            { "transport", transport },
+            { "partition", partition },
+        });
+
+    public void RecordAudit(string action, string result) =>
+        _auditEvents.Add(1, new TagList
+        {
+            { "action", action },
+            { "result", result },
+        });
+
+    public void RecordConnectionOutcome(string outcome, string elapsedBucket) =>
+        _connectionOutcomes.Add(1, new TagList
+        {
+            { "outcome", outcome },
+            { "elapsed_bucket", elapsedBucket },
+        });
+
+    public void RecordOperatorAuthentication(string result) =>
+        _operatorAuthentication.Add(1, new TagList
+        {
+            { "result", result },
+        });
+
+    public void RecordPairingLatency(double elapsedMilliseconds) =>
+        _pairingLatency.Record(elapsedMilliseconds);
+
+    public void Dispose()
+    {
+        _activities.Dispose();
+        _meter.Dispose();
+    }
+}

src/FinalFactory.Rendezvous.Server/Observability/TelemetryMiddleware.cs

@@ -0,0 +1,32 @@
+using System.Diagnostics;
+
+namespace FinalFactory.Rendezvous.Server.Observability;
+
+internal sealed class TelemetryMiddleware(
+    RequestDelegate next,
+    RendezvousTelemetry telemetry)
+{
+    public async Task InvokeAsync(HttpContext context)
+    {
+        string operation = context.GetEndpoint()?.Metadata.GetMetadata<IEndpointNameMetadata>()
+            ?.EndpointName ?? "Unmatched";
+        long started = Stopwatch.GetTimestamp();
+        using Activity? activity = telemetry.StartActivity(
+            $"HTTP {operation}",
+            ActivityKind.Server);
+        string correlationId = activity?.TraceId.ToString() ?? Guid.NewGuid().ToString("N");
+        context.Response.Headers["X-Rendezvous-Correlation-ID"] = correlationId;
+        activity?.SetTag("rendezvous.operation", operation);
+        try
+        {
+            await next(context).ConfigureAwait(false);
+        }
+        finally
+        {
+            telemetry.RecordHttp(
+                operation,
+                context.Response.StatusCode,
+                Stopwatch.GetElapsedTime(started).TotalMilliseconds);
+        }
+    }
+}

src/FinalFactory.Rendezvous.Server/Operations/OperatorEndpoints.cs

@@ -0,0 +1,428 @@
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Observability;
+using FinalFactory.Rendezvous.Server.Provisioning;
+using FinalFactory.Rendezvous.Server.State;
+using Microsoft.AspNetCore.Mvc;
+
+namespace FinalFactory.Rendezvous.Server.Operations;
+
+internal static class OperatorEndpoints
+{
+    private const string CorrelationHeader = "X-Rendezvous-Correlation-ID";
+
+    public static IEndpointRouteBuilder MapOperatorEndpoints(this IEndpointRouteBuilder endpoints)
+    {
+        RouteGroupBuilder group = endpoints.MapGroup("/v1/operator").WithTags("Operator");
+        group.MapGet("/status", GetStatus)
+            .Produces<OperatorStatusResponse>()
+            .Produces<ApiError>(StatusCodes.Status401Unauthorized)
+            .Produces<ApiError>(StatusCodes.Status403Forbidden)
+            .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .WithName("GetOperatorStatus");
+        group.MapPost("/listings/revoke", RevokeListing)
+            .Accepts<RevokeListingRequest>("application/json")
+            .Produces<OperatorActionResponse>()
+            .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
+            .Produces<ApiError>(StatusCodes.Status401Unauthorized)
+            .Produces<ApiError>(StatusCodes.Status403Forbidden)
+            .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
+            .WithName("RevokeOperatorListing");
+        group.MapPost("/principals/revoke", RevokePrincipal)
+            .Accepts<RevokePrincipalRequest>("application/json")
+            .Produces<OperatorActionResponse>()
+            .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
+            .Produces<ApiError>(StatusCodes.Status401Unauthorized)
+            .Produces<ApiError>(StatusCodes.Status403Forbidden)
+            .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .Produces<ApiError>(StatusCodes.Status503ServiceUnavailable)
+            .WithName("RevokeOperatorPrincipal");
+        group.MapPost("/keys/revoke", RevokeSigningKey)
+            .Accepts<RevokeSigningKeyRequest>("application/json")
+            .Produces<OperatorActionResponse>()
+            .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
+            .Produces<ApiError>(StatusCodes.Status401Unauthorized)
+            .Produces<ApiError>(StatusCodes.Status403Forbidden)
+            .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .WithName("RevokeOperatorSigningKey");
+        group.MapPost("/drain", BeginDrain)
+            .Accepts<BeginDrainRequest>("application/json")
+            .Produces<OperatorActionResponse>()
+            .Produces<ApiError>(StatusCodes.Status400BadRequest)
+            .Produces<ApiError>(StatusCodes.Status413PayloadTooLarge)
+            .Produces<ApiError>(StatusCodes.Status401Unauthorized)
+            .Produces<ApiError>(StatusCodes.Status403Forbidden)
+            .Produces<ApiError>(StatusCodes.Status404NotFound)
+            .Produces<ApiError>(StatusCodes.Status429TooManyRequests)
+            .WithName("BeginOperatorDrain");
+        return endpoints;
+    }
+
+    private static IResult GetStatus(
+        [FromHeader(Name = "Authorization")] string? authorization,
+        [FromServices] PrincipalCredentialService credentials,
+        [FromServices] IWallClock clock,
+        [FromServices] OperatorService service,
+        [FromServices] AuditTrail audit,
+        [FromServices] RendezvousTelemetry telemetry,
+        HttpContext context)
+    {
+        if (!TryAuthorize(
+                authorization,
+                OperatorPermission.ReadPolicy,
+                "inspect-status",
+                credentials,
+                clock,
+                audit,
+                telemetry,
+                context,
+                out OperatorPrincipal? principal,
+                out IResult? failure))
+        {
+            return failure!;
+        }
+
+        OperatorStatusResponse response = service.GetStatus();
+        audit.Record(
+            principal!.Subject,
+            "inspect-status",
+            "succeeded",
+            "service",
+            "rendezvous",
+            Correlation(context));
+        return Results.Ok(response);
+    }
+
+    private static IResult RevokeListing(
+        [FromBody] RevokeListingRequest request,
+        [FromHeader(Name = "Authorization")] string? authorization,
+        [FromServices] PrincipalCredentialService credentials,
+        [FromServices] IWallClock clock,
+        [FromServices] OperatorService service,
+        [FromServices] AuditTrail audit,
+        [FromServices] RendezvousTelemetry telemetry,
+        HttpContext context,
+        CancellationToken cancellationToken)
+    {
+        if (!TryAuthorize(
+                authorization,
+                OperatorPermission.RevokePublisher,
+                "revoke-listing",
+                credentials,
+                clock,
+                audit,
+                telemetry,
+                context,
+                out OperatorPrincipal? principal,
+                out IResult? failure))
+        {
+            return failure!;
+        }
+
+        bool valid = SessionListingId.TryParse(request.ListingId, out SessionListingId listingId);
+        if (!valid || !string.Equals(request.ListingId, request.ConfirmListingId, StringComparison.Ordinal))
+        {
+            AuditRejected(audit, principal!, "revoke-listing", "listing", request.ListingId, context);
+            return BadRequest("A valid listing ID and an exact repeated confirmation are required.");
+        }
+
+        StoreResult<bool> result = service.RevokeListing(listingId, cancellationToken);
+        return StoreActionResult(
+            result.Code,
+            audit,
+            principal!,
+            "revoke-listing",
+            "listing",
+            request.ListingId,
+            context,
+            affectedResources: result.Succeeded ? 1 : null);
+    }
+
+    private static IResult RevokePrincipal(
+        [FromBody] RevokePrincipalRequest request,
+        [FromHeader(Name = "Authorization")] string? authorization,
+        [FromServices] PrincipalCredentialService credentials,
+        [FromServices] IWallClock clock,
+        [FromServices] OperatorService service,
+        [FromServices] AuditTrail audit,
+        [FromServices] RendezvousTelemetry telemetry,
+        HttpContext context,
+        CancellationToken cancellationToken)
+    {
+        if (!TryAuthorize(
+                authorization,
+                OperatorPermission.RevokePublisher,
+                "revoke-principal",
+                credentials,
+                clock,
+                audit,
+                telemetry,
+                context,
+                out OperatorPrincipal? principal,
+                out IResult? failure))
+        {
+            return failure!;
+        }
+
+        bool safeSubject = request.Subject is { Length: > 0 and <= 128 }
+            && request.Subject.All(static character => character is >= '!' and <= '~');
+        if (!safeSubject
+            || !string.Equals(request.Subject, request.ConfirmSubject, StringComparison.Ordinal)
+            || request.LifetimeSeconds is < 1 or > 600)
+        {
+            AuditRejected(audit, principal!, "revoke-principal", "principal", request.Subject, context);
+            return BadRequest("A valid subject, exact repeated confirmation, and 1-600 second lifetime are required.");
+        }
+
+        StoreResult<int> result = service.RevokePrincipal(
+            request.Subject,
+            TimeSpan.FromSeconds(request.LifetimeSeconds),
+            cancellationToken);
+        return StoreActionResult(
+            result.Code,
+            audit,
+            principal!,
+            "revoke-principal",
+            "principal",
+            request.Subject,
+            context,
+            result.Value);
+    }
+
+    private static IResult RevokeSigningKey(
+        [FromBody] RevokeSigningKeyRequest request,
+        [FromHeader(Name = "Authorization")] string? authorization,
+        [FromServices] PrincipalCredentialService credentials,
+        [FromServices] IWallClock clock,
+        [FromServices] OperatorService service,
+        [FromServices] AuditTrail audit,
+        [FromServices] RendezvousTelemetry telemetry,
+        HttpContext context)
+    {
+        if (!TryAuthorize(
+                authorization,
+                OperatorPermission.RotateKeys,
+                "revoke-signing-key",
+                credentials,
+                clock,
+                audit,
+                telemetry,
+                context,
+                out OperatorPrincipal? principal,
+                out IResult? failure))
+        {
+            return failure!;
+        }
+
+        bool safeKeyId = request.KeyId is { Length: > 0 and <= 64 }
+            && request.KeyId.All(static character => character is
+                >= 'A' and <= 'Z'
+                or >= 'a' and <= 'z'
+                or >= '0' and <= '9'
+                or '-'
+                or '_');
+        if (!safeKeyId || !string.Equals(request.KeyId, request.ConfirmKeyId, StringComparison.Ordinal))
+        {
+            AuditRejected(audit, principal!, "revoke-signing-key", "signing-key", request.KeyId, context);
+            return BadRequest("A valid key ID and an exact repeated confirmation are required.");
+        }
+
+        bool revoked = service.RevokeSigningKey(request.KeyId);
+        string result = revoked ? "succeeded" : "not-found";
+        audit.Record(
+            principal!.Subject,
+            "revoke-signing-key",
+            result,
+            "signing-key",
+            request.KeyId,
+            Correlation(context));
+        return revoked
+            ? Results.Ok(new OperatorActionResponse { Status = "completed" })
+            : Error(RendezvousErrorCode.NotFound, "The requested resource was not found.");
+    }
+
+    private static IResult BeginDrain(
+        [FromBody] BeginDrainRequest request,
+        [FromHeader(Name = "Authorization")] string? authorization,
+        [FromServices] PrincipalCredentialService credentials,
+        [FromServices] IWallClock clock,
+        [FromServices] OperatorService service,
+        [FromServices] AuditTrail audit,
+        [FromServices] RendezvousTelemetry telemetry,
+        HttpContext context,
+        CancellationToken cancellationToken)
+    {
+        if (!TryAuthorize(
+                authorization,
+                OperatorPermission.ManagePolicy,
+                "begin-drain",
+                credentials,
+                clock,
+                audit,
+                telemetry,
+                context,
+                out OperatorPrincipal? principal,
+                out IResult? failure))
+        {
+            return failure!;
+        }
+
+        if (!string.Equals(request.Confirmation, "DRAIN", StringComparison.Ordinal))
+        {
+            AuditRejected(audit, principal!, "begin-drain", "service", "rendezvous", context);
+            return BadRequest("The confirmation value must be exactly 'DRAIN'.");
+        }
+
+        service.BeginDrain(cancellationToken);
+        audit.Record(
+            principal!.Subject,
+            "begin-drain",
+            "succeeded",
+            "service",
+            "rendezvous",
+            Correlation(context));
+        return Results.Ok(new OperatorActionResponse { Status = "draining" });
+    }
+
+    private static bool TryAuthorize(
+        string? authorization,
+        OperatorPermission requiredPermission,
+        string operation,
+        PrincipalCredentialService credentials,
+        IWallClock clock,
+        AuditTrail audit,
+        RendezvousTelemetry telemetry,
+        HttpContext context,
+        out OperatorPrincipal? principal,
+        out IResult? failure)
+    {
+        principal = null;
+        failure = null;
+        const string prefix = "Bearer ";
+        if (authorization is null
+            || !authorization.StartsWith(prefix, StringComparison.OrdinalIgnoreCase))
+        {
+            telemetry.RecordOperatorAuthentication("rejected");
+            failure = AuthenticationRequired(context);
+            return false;
+        }
+
+        CredentialValidationResult validation = credentials.Validate(
+            authorization[prefix.Length..],
+            clock.UtcNow);
+        if (!validation.IsValid || validation.Principal is not OperatorPrincipal candidate)
+        {
+            telemetry.RecordOperatorAuthentication("rejected");
+            failure = AuthenticationRequired(context);
+            return false;
+        }
+
+        if (!candidate.Permissions.Contains(requiredPermission))
+        {
+            telemetry.RecordOperatorAuthentication("forbidden");
+            audit.Record(
+                candidate.Subject,
+                operation,
+                "forbidden",
+                "operator-operation",
+                operation,
+                Correlation(context));
+            failure = Error(RendezvousErrorCode.Forbidden, "The operator is not authorized for this operation.");
+            return false;
+        }
+
+        telemetry.RecordOperatorAuthentication("accepted");
+        principal = candidate;
+        return true;
+    }
+
+    private static IResult StoreActionResult(
+        StoreResultCode code,
+        AuditTrail audit,
+        OperatorPrincipal principal,
+        string action,
+        string targetKind,
+        string targetIdentifier,
+        HttpContext context,
+        int? affectedResources)
+    {
+        string auditResult = code == StoreResultCode.Success
+            ? "succeeded"
+            : code.ToString().ToLowerInvariant();
+        audit.Record(
+            principal.Subject,
+            action,
+            auditResult,
+            targetKind,
+            targetIdentifier,
+            Correlation(context));
+        return code switch
+        {
+            StoreResultCode.Success => Results.Ok(new OperatorActionResponse
+            {
+                Status = "completed",
+                AffectedResources = affectedResources,
+            }),
+            StoreResultCode.NotFound => Error(
+                RendezvousErrorCode.NotFound,
+                "The requested resource was not found."),
+            StoreResultCode.CapacityExceeded => Error(
+                RendezvousErrorCode.CapacityExceeded,
+                "The operation could not be retained within the configured capacity."),
+            StoreResultCode.ServiceUnavailable or StoreResultCode.Draining => Error(
+                RendezvousErrorCode.ServiceUnavailable,
+                "The service is not available for this operation."),
+            _ => Error(RendezvousErrorCode.Conflict, "The operation could not be completed."),
+        };
+    }
+
+    private static void AuditRejected(
+        AuditTrail audit,
+        OperatorPrincipal principal,
+        string action,
+        string targetKind,
+        string? targetIdentifier,
+        HttpContext context) => audit.Record(
+            principal.Subject,
+            action,
+            "rejected",
+            targetKind,
+            targetIdentifier ?? string.Empty,
+            Correlation(context));
+
+    private static string Correlation(HttpContext context) =>
+        context.Response.Headers[CorrelationHeader].ToString() is { Length: > 0 } value
+            ? value
+            : "unavailable";
+
+    private static IResult AuthenticationRequired(HttpContext context)
+    {
+        context.Response.Headers.WWWAuthenticate = "Bearer realm=\"operator\"";
+        return Error(
+            RendezvousErrorCode.AuthenticationRequired,
+            "A valid operator bearer credential is required.");
+    }
+
+    private static IResult BadRequest(string message) => Error(RendezvousErrorCode.InvalidRequest, message);
+
+    private static IResult Error(RendezvousErrorCode code, string message) => Results.Json(
+        new ApiError { Code = code, Message = message },
+        ContractJson.Options,
+        statusCode: code switch
+        {
+            RendezvousErrorCode.AuthenticationRequired => StatusCodes.Status401Unauthorized,
+            RendezvousErrorCode.Forbidden => StatusCodes.Status403Forbidden,
+            RendezvousErrorCode.NotFound => StatusCodes.Status404NotFound,
+            RendezvousErrorCode.CapacityExceeded => StatusCodes.Status429TooManyRequests,
+            RendezvousErrorCode.ServiceUnavailable => StatusCodes.Status503ServiceUnavailable,
+            RendezvousErrorCode.Conflict => StatusCodes.Status409Conflict,
+            _ => StatusCodes.Status400BadRequest,
+        });
+}

src/FinalFactory.Rendezvous.Server/Operations/OperatorModels.cs

@@ -0,0 +1,82 @@
+namespace FinalFactory.Rendezvous.Server.Operations;
+
+internal sealed record OperatorStatusResponse
+{
+    public required string Status { get; init; }
+    public required OperatorReadinessResponse Readiness { get; init; }
+    public required OperatorStoreResponse Store { get; init; }
+    public required IReadOnlyList<OperatorTenantResponse> Tenants { get; init; }
+    public required IReadOnlyList<OperatorSigningKeyResponse> SigningKeys { get; init; }
+    public required IReadOnlyDictionary<string, long> AuditCounts { get; init; }
+}
+
+internal sealed record OperatorReadinessResponse
+{
+    public required bool HttpListener { get; init; }
+    public required bool UdpIpv4Listener { get; init; }
+    public required bool UdpIpv6Listener { get; init; }
+    public required bool Provisioning { get; init; }
+    public required bool Store { get; init; }
+    public required bool Draining { get; init; }
+}
+
+internal sealed record OperatorStoreResponse
+{
+    public required int ActiveListings { get; init; }
+    public required int FreshPresenceBindings { get; init; }
+    public required int ActiveJoinAttempts { get; init; }
+    public required int RetainedOutcomeReports { get; init; }
+    public required int ReplayMarkers { get; init; }
+    public required int PrincipalRevocations { get; init; }
+    public required int IdempotencyEntries { get; init; }
+    public required long MaintenanceSweeps { get; init; }
+    public required long ExpiryChurn { get; init; }
+}
+
+internal sealed record OperatorTenantResponse
+{
+    public required string GameId { get; init; }
+    public required string EnvironmentId { get; init; }
+    public required string Status { get; init; }
+}
+
+internal sealed record OperatorSigningKeyResponse
+{
+    public required string KeyId { get; init; }
+    public required string Status { get; init; }
+    public required DateTimeOffset SignUntil { get; init; }
+    public required DateTimeOffset VerifyUntil { get; init; }
+    public string? GameId { get; init; }
+    public string? EnvironmentId { get; init; }
+    public required IReadOnlyList<string> CredentialKinds { get; init; }
+}
+
+internal sealed record OperatorActionResponse
+{
+    public required string Status { get; init; }
+    public int? AffectedResources { get; init; }
+}
+
+internal sealed record RevokeListingRequest
+{
+    public required string ListingId { get; init; }
+    public required string ConfirmListingId { get; init; }
+}
+
+internal sealed record RevokePrincipalRequest
+{
+    public required string Subject { get; init; }
+    public required string ConfirmSubject { get; init; }
+    public required int LifetimeSeconds { get; init; }
+}
+
+internal sealed record RevokeSigningKeyRequest
+{
+    public required string KeyId { get; init; }
+    public required string ConfirmKeyId { get; init; }
+}
+
+internal sealed record BeginDrainRequest
+{
+    public required string Confirmation { get; init; }
+}

src/FinalFactory.Rendezvous.Server/Operations/OperatorService.cs

@@ -0,0 +1,81 @@
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Observability;
+using FinalFactory.Rendezvous.Server.Provisioning;
+using FinalFactory.Rendezvous.Server.State;
+
+namespace FinalFactory.Rendezvous.Server.Operations;
+
+internal sealed class OperatorService(
+    InMemoryEphemeralRendezvousStore store,
+    ProvisioningRuntime provisioning,
+    RendezvousReadiness readiness,
+    AuditTrail audit,
+    IWallClock clock)
+{
+    public OperatorStatusResponse GetStatus()
+    {
+        ReadinessSnapshot readinessSnapshot = readiness.GetSnapshot();
+        EphemeralStoreSnapshot storeSnapshot = store.GetSnapshot();
+        return new OperatorStatusResponse
+        {
+            Status = readinessSnapshot.IsReady ? "ready" : "not-ready",
+            Readiness = new OperatorReadinessResponse
+            {
+                HttpListener = readinessSnapshot.HttpListenerReady,
+                UdpIpv4Listener = readinessSnapshot.UdpIpv4ListenerReady,
+                UdpIpv6Listener = readinessSnapshot.UdpIpv6ListenerReady,
+                Provisioning = readinessSnapshot.ProvisioningReady,
+                Store = readinessSnapshot.StoreAvailable,
+                Draining = readinessSnapshot.Draining,
+            },
+            Store = new OperatorStoreResponse
+            {
+                ActiveListings = storeSnapshot.ActiveListings,
+                FreshPresenceBindings = storeSnapshot.FreshPresenceBindings,
+                ActiveJoinAttempts = storeSnapshot.ActiveJoinAttempts,
+                RetainedOutcomeReports = storeSnapshot.RetainedOutcomeReports,
+                ReplayMarkers = storeSnapshot.ReplayMarkers,
+                PrincipalRevocations = storeSnapshot.PrincipalRevocations,
+                IdempotencyEntries = storeSnapshot.IdempotencyEntries,
+                MaintenanceSweeps = storeSnapshot.MaintenanceSweeps,
+                ExpiryChurn = storeSnapshot.ExpiryChurn,
+            },
+            Tenants = provisioning.Policies.EnabledPolicies
+                .OrderBy(static policy => policy.GameId.Value, StringComparer.Ordinal)
+                .ThenBy(static policy => policy.EnvironmentId.Value, StringComparer.Ordinal)
+                .Select(static policy => new OperatorTenantResponse
+                {
+                    GameId = policy.GameId.Value,
+                    EnvironmentId = policy.EnvironmentId.Value,
+                    Status = "enabled",
+                })
+                .ToArray(),
+            SigningKeys = provisioning.SigningKeys.GetStatuses(clock.UtcNow)
+                .Select(static key => new OperatorSigningKeyResponse
+                {
+                    KeyId = key.KeyId,
+                    Status = key.Status,
+                    SignUntil = key.SignUntil,
+                    VerifyUntil = key.VerifyUntil,
+                    GameId = key.GameId,
+                    EnvironmentId = key.EnvironmentId,
+                    CredentialKinds = key.CredentialKinds,
+                })
+                .ToArray(),
+            AuditCounts = audit.GetAggregateCounts(),
+        };
+    }
+
+    public StoreResult<bool> RevokeListing(
+        SessionListingId listingId,
+        CancellationToken cancellationToken) => store.RevokeListing(listingId, cancellationToken);
+
+    public StoreResult<int> RevokePrincipal(
+        string subject,
+        TimeSpan lifetime,
+        CancellationToken cancellationToken) => store.RevokePrincipal(subject, lifetime, cancellationToken);
+
+    public bool RevokeSigningKey(string keyId) => provisioning.SigningKeys.Revoke(keyId);
+
+    public void BeginDrain(CancellationToken cancellationToken) => store.BeginDrain(cancellationToken);
+}

src/FinalFactory.Rendezvous.Server/Program.cs

@@ -1,15 +1,24 @@
 using System.Net;
 using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.Browser;
+using FinalFactory.Rendezvous.Server.ConnectionOutcomes;
+using FinalFactory.Rendezvous.Server.Deployment;
 using FinalFactory.Rendezvous.Server.Http;
 using FinalFactory.Rendezvous.Server.JoinAttempts;
+using FinalFactory.Rendezvous.Server.Observability;
+using FinalFactory.Rendezvous.Server.Operations;
 using FinalFactory.Rendezvous.Server.Provisioning;
 using FinalFactory.Rendezvous.Server.Sessions;
 using FinalFactory.Rendezvous.Server.State;
 using FinalFactory.Rendezvous.Server.Transport;
+using Microsoft.AspNetCore.HttpOverrides;
 using Microsoft.OpenApi;
 
 WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
+builder.Logging.AddFilter(
+    "Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware",
+    LogLevel.None);
 bool isOpenApiGeneration = string.Equals(
     System.Reflection.Assembly.GetEntryAssembly()?.GetName().Name,
     "GetDocument.Insider",
@@ -50,6 +59,22 @@ builder.Services.AddOpenApi("v1", static options =>
             BearerFormat = "rv1 publisher credential",
             Description = "Tenant-scoped publisher credential issued during game provisioning.",
         };
+        const string attemptSchemeName = "JoinAttemptCapability";
+        document.Components.SecuritySchemes[attemptSchemeName] = new OpenApiSecurityScheme
+        {
+            Type = SecuritySchemeType.ApiKey,
+            Name = "X-Rendezvous-Client-Punch-Capability",
+            In = ParameterLocation.Header,
+            Description = "Attempt-scoped client capability returned only to the joining caller.",
+        };
+        const string operatorSchemeName = "OperatorBearer";
+        document.Components.SecuritySchemes[operatorSchemeName] = new OpenApiSecurityScheme
+        {
+            Type = SecuritySchemeType.Http,
+            Scheme = "bearer",
+            BearerFormat = "rv1 operator credential",
+            Description = "Operator-only credential with an explicit permission set.",
+        };
 
         HashSet<string> securedOperations = new(StringComparer.Ordinal)
         {
@@ -58,7 +83,17 @@ builder.Services.AddOpenApi("v1", static options =>
             "UpdateSession",
             "DeleteSession",
         };
+        HashSet<string> operatorOperations = new(StringComparer.Ordinal)
+        {
+            "GetOperatorStatus",
+            "RevokeOperatorListing",
+            "RevokeOperatorPrincipal",
+            "RevokeOperatorSigningKey",
+            "BeginOperatorDrain",
+        };
         OpenApiSecuritySchemeReference reference = new(schemeName, document, null);
+        OpenApiSecuritySchemeReference attemptReference = new(attemptSchemeName, document, null);
+        OpenApiSecuritySchemeReference operatorReference = new(operatorSchemeName, document, null);
         foreach (OpenApiPathItem path in document.Paths.Values)
         {
             if (path.Operations is null)
@@ -75,6 +110,71 @@ builder.Services.AddOpenApi("v1", static options =>
                     [reference] = [],
                 });
             }
+
+            foreach (OpenApiOperation operation in path.Operations.Values.Where(
+                         operation => operation.OperationId is
+                             "CancelJoinAttempt" or "ReportConnectionOutcome"))
+            {
+                operation.Security ??= [];
+                operation.Security.Add(new OpenApiSecurityRequirement
+                {
+                    [attemptReference] = [],
+                });
+            }
+
+            foreach (OpenApiOperation operation in path.Operations.Values.Where(
+                         operation => operatorOperations.Contains(
+                             operation.OperationId ?? string.Empty)))
+            {
+                operation.Security ??= [];
+                operation.Security.Add(new OpenApiSecurityRequirement
+                {
+                    [operatorReference] = [],
+                });
+            }
+
+            foreach (OpenApiOperation operation in path.Operations.Values)
+            {
+                if (operation.Responses is null)
+                {
+                    continue;
+                }
+
+                foreach ((string status, IOpenApiResponse response) in operation.Responses)
+                {
+                    if (response is not OpenApiResponse concreteResponse)
+                    {
+                        continue;
+                    }
+
+                    concreteResponse.Headers ??=
+                        new Dictionary<string, IOpenApiHeader>(StringComparer.OrdinalIgnoreCase);
+                    concreteResponse.Headers["X-Rendezvous-Correlation-ID"] = new OpenApiHeader
+                    {
+                        Description = "Safe request correlation identifier generated by the service.",
+                        Schema = new OpenApiSchema
+                        {
+                            Type = JsonSchemaType.String,
+                        },
+                    };
+                    if (string.Equals(
+                            status,
+                            StatusCodes.Status429TooManyRequests.ToString(
+                                System.Globalization.CultureInfo.InvariantCulture),
+                            StringComparison.Ordinal))
+                    {
+                        concreteResponse.Headers["Retry-After"] = new OpenApiHeader
+                        {
+                            Description = "Whole seconds before the caller should retry (1-60).",
+                            Schema = new OpenApiSchema
+                            {
+                                Type = JsonSchemaType.Integer,
+                                Format = "int32",
+                            },
+                        };
+                    }
+                }
+            }
         }
 
         return Task.CompletedTask;
@@ -86,15 +186,90 @@ builder.Services.Configure<RouteHandlerOptions>(static options =>
     options.ThrowOnBadRequest = true);
 builder.Services.AddProblemDetails();
 builder.Services.AddExceptionHandler<RendezvousExceptionHandler>();
+builder.WebHost.ConfigureKestrel(static options =>
+    options.Limits.MaxRequestBodySize = ContractLimits.HttpRequestMaxBytes);
+
+builder.Services
+    .AddOptions<AbuseProtectionOptions>()
+    .BindConfiguration(AbuseProtectionOptions.SectionName)
+    .ValidateDataAnnotations()
+    .Validate(
+        options => options.HttpOptionalRequestsPerWindow
+                   < options.HttpGlobalRequestsPerWindow,
+        "The optional HTTP request budget must leave global capacity for lease operations.")
+    .Validate(
+        options => options.HttpOptionalConcurrency < options.HttpGlobalConcurrency,
+        "The optional HTTP concurrency budget must leave global capacity for lease operations.")
+    .Validate(
+        options => options.HttpOptionalIpPrefixRequestsPerWindow
+                   < options.HttpIpPrefixRequestsPerWindow,
+        "The optional HTTP source budget must leave capacity for lease operations.")
+    .Validate(
+        options => options.HttpOptionalIpPrefixConcurrency
+                   < options.HttpIpPrefixConcurrency,
+        "The optional HTTP source concurrency must leave capacity for lease operations.")
+    .Validate(
+        options => options.CriticalTrackedKeyReserve >= 16
+                   && options.UdpTrackedKeyLimit + options.CriticalTrackedKeyReserve
+                   < options.MaxTrackedKeys,
+        "The tracked-key reserve must leave at least 16 keys for critical operations.")
+    .Validate(
+        options => options.TrustedProxyAddresses is { Length: <= 32 } addresses
+                   && addresses.All(
+                       static value => IPAddress.TryParse(value, out _)),
+        "Trusted proxy addresses must contain at most 32 literal IP addresses.")
+    .Validate(
+        options => options.OperatorAllowedAddresses is { Length: <= 32 } addresses
+                   && addresses.All(
+                       static value => IPAddress.TryParse(value, out _)),
+        "Operator allowed addresses must contain at most 32 literal IP addresses.")
+    .ValidateOnStart();
+builder.Services.AddSingleton<AbuseProtectionService>();
+builder.Services
+    .AddOptions<AuditOptions>()
+    .BindConfiguration(AuditOptions.SectionName)
+    .ValidateDataAnnotations()
+    .ValidateOnStart();
+AbuseProtectionOptions configuredAbuseProtection = builder.Configuration
+    .GetSection(AbuseProtectionOptions.SectionName)
+    .Get<AbuseProtectionOptions>() ?? new AbuseProtectionOptions();
+builder.Services.Configure<ForwardedHeadersOptions>(options =>
+    TrustedProxyForwarding.Configure(options, configuredAbuseProtection));
+
+DeploymentOptions deploymentOptions = builder.Configuration
+    .GetSection(DeploymentOptions.SectionName)
+    .Get<DeploymentOptions>() ?? new DeploymentOptions();
+if (!builder.Environment.IsDevelopment() && !isOpenApiGeneration)
+{
+    IReadOnlyList<string> deploymentErrors = deploymentOptions.ValidateProduction(
+        configuredAbuseProtection,
+        builder.Configuration["AllowedHosts"]);
+    if (deploymentErrors.Count > 0)
+    {
+        throw new DeploymentConfigurationException(deploymentErrors);
+    }
+}
+
+builder.Services.AddSingleton(Microsoft.Extensions.Options.Options.Create(deploymentOptions));
+builder.Services.Configure<HostOptions>(options =>
+    options.ShutdownTimeout = TimeSpan.FromSeconds(deploymentOptions.DrainDeadlineSeconds + 10));
 
 SystemRendezvousClock rendezvousClock = new();
-EphemeralStoreOptions stateOptions = new();
+EphemeralStoreOptions stateOptions = new()
+{
+    GracefulDrainLifetime = TimeSpan.FromSeconds(deploymentOptions.DrainDeadlineSeconds),
+};
 InMemoryEphemeralRendezvousStore stateStore = new(
     stateOptions,
     rendezvousClock,
     rendezvousClock);
+builder.Services.AddSingleton(stateStore);
 builder.Services.AddSingleton<IEphemeralRendezvousStore>(stateStore);
 builder.Services.AddSingleton<IWallClock>(rendezvousClock);
+builder.Services.AddSingleton<IMonotonicClock>(rendezvousClock);
+builder.Services.AddSingleton<RendezvousTelemetry>();
+builder.Services.AddSingleton<AuditTrail>();
+builder.Services.AddSingleton<RendezvousReadiness>();
 
 if (isOpenApiGeneration)
 {
@@ -125,6 +300,9 @@ else
     builder.Services.AddSingleton<SessionBrowserService>();
     builder.Services.AddSingleton<JoinAttemptCursorCodec>();
     builder.Services.AddSingleton<JoinAttemptService>();
+    builder.Services.AddSingleton<ConnectionOutcomeMetrics>();
+    builder.Services.AddSingleton<ConnectionOutcomeService>();
+    builder.Services.AddSingleton<OperatorService>();
     builder.Services.AddSingleton(new ProvisioningReadiness(true));
 }
 
@@ -148,36 +326,24 @@ if (!isOpenApiGeneration)
     builder.Services.AddSingleton<NatMediationProcessor>();
     builder.Services.AddHostedService(static services =>
         services.GetRequiredService<UdpMediatorService>());
+    // Hosted services stop in reverse registration order. Drain must complete while
+    // Kestrel and the UDP mediator are still able to finish bounded in-flight work.
+    builder.Services.AddHostedService<GracefulDrainService>();
 }
 
 WebApplication app = builder.Build();
-app.Lifetime.ApplicationStopping.Register(() => stateStore.BeginDrain());
 
+if (TrustedProxyForwarding.IsEnabled(configuredAbuseProtection))
+{
+    app.UseForwardedHeaders();
+}
+app.UseMiddleware<TelemetryMiddleware>();
 app.UseExceptionHandler();
+app.UseMiddleware<HttpAbuseProtectionMiddleware>();
 app.MapOpenApi();
 app.MapRendezvousContractEndpoints();
-app.MapGet(
-        "/health/live",
-        static () => Results.Ok(new HealthResponse { Status = "live" }))
-    .Produces<HealthResponse>()
-    .WithName("GetLiveness")
-    .WithTags("Health");
-app.MapGet(
-    "/health/ready",
-    static (
-        UdpMediatorService mediator,
-        ProvisioningReadiness provisioning,
-        IEphemeralRendezvousStore state) =>
-        mediator.LocalEndpoint is null
-        || !provisioning.IsReady
-        || !state.IsAvailable
-        || state.IsDraining
-        ? Results.StatusCode(StatusCodes.Status503ServiceUnavailable)
-        : Results.Ok(new HealthResponse { Status = "ready" }))
-    .Produces<HealthResponse>()
-    .Produces(StatusCodes.Status503ServiceUnavailable)
-    .WithName("GetReadiness")
-    .WithTags("Health");
+app.MapOperatorEndpoints();
+app.MapRendezvousHealthEndpoints();
 
 await app.RunAsync();
 

src/FinalFactory.Rendezvous.Server/Properties/AssemblyInfo.cs

@@ -1,3 +1,4 @@
 using System.Runtime.CompilerServices;
 
 [assembly: InternalsVisibleTo("FinalFactory.Rendezvous.Tests")]
+[assembly: InternalsVisibleTo("FinalFactory.Rendezvous.Capacity")]

src/FinalFactory.Rendezvous.Server/Provisioning/SecretProviders.cs

@@ -40,18 +40,32 @@ internal sealed class SecretMaterial : IDisposable
 
 internal sealed class EnvironmentSecretProvider : ISecretProvider
 {
-    private const string Prefix = "env:";
+    private const string EnvironmentPrefix = "env:";
+    private const string FilePrefix = "file:";
+    private const int MaximumSecretBytes = 4096;
 
     public bool TryGetSecret(string reference, out SecretMaterial? secret)
     {
         secret = null;
-        if (!reference.StartsWith(Prefix, StringComparison.Ordinal)
-            || reference.Length == Prefix.Length)
+        if (reference.StartsWith(EnvironmentPrefix, StringComparison.Ordinal)
+            && reference.Length > EnvironmentPrefix.Length)
         {
-            return false;
+            return TryGetEnvironmentSecret(reference[EnvironmentPrefix.Length..], out secret);
         }
 
-        string? encoded = Environment.GetEnvironmentVariable(reference[Prefix.Length..]);
+        if (reference.StartsWith(FilePrefix, StringComparison.Ordinal)
+            && reference.Length > FilePrefix.Length)
+        {
+            return TryGetFileSecret(reference[FilePrefix.Length..], out secret);
+        }
+
+        return false;
+    }
+
+    private static bool TryGetEnvironmentSecret(string variableName, out SecretMaterial? secret)
+    {
+        secret = null;
+        string? encoded = Environment.GetEnvironmentVariable(variableName);
         if (string.IsNullOrEmpty(encoded))
         {
             return false;
@@ -60,6 +74,12 @@ internal sealed class EnvironmentSecretProvider : ISecretProvider
         try
         {
             byte[] bytes = Convert.FromBase64String(encoded);
+            if (bytes.Length is 0 or > MaximumSecretBytes)
+            {
+                CryptographicOperations.ZeroMemory(bytes);
+                return false;
+            }
+
             secret = new SecretMaterial(bytes);
             CryptographicOperations.ZeroMemory(bytes);
             return true;
@@ -69,6 +89,47 @@ internal sealed class EnvironmentSecretProvider : ISecretProvider
             return false;
         }
     }
+
+    private static bool TryGetFileSecret(string path, out SecretMaterial? secret)
+    {
+        secret = null;
+        byte[]? bytes = null;
+        try
+        {
+            FileInfo file = new(path);
+            if (!file.Exists
+                || !Path.IsPathFullyQualified(path)
+                || file.LinkTarget is not null
+                || file.Length is <= 0 or > MaximumSecretBytes)
+            {
+                return false;
+            }
+
+            bytes = File.ReadAllBytes(path);
+            if (bytes.Length is 0 or > MaximumSecretBytes)
+            {
+                return false;
+            }
+
+            secret = new SecretMaterial(bytes);
+            return true;
+        }
+        catch (Exception exception) when (exception is IOException
+                                           or UnauthorizedAccessException
+                                           or ArgumentException
+                                           or NotSupportedException
+                                           or System.Security.SecurityException)
+        {
+            return false;
+        }
+        finally
+        {
+            if (bytes is not null)
+            {
+                CryptographicOperations.ZeroMemory(bytes);
+            }
+        }
+    }
 }
 
 internal sealed class EphemeralDevelopmentSecretProvider : ISecretProvider, IDisposable

src/FinalFactory.Rendezvous.Server/Provisioning/SigningKeyRing.cs

@@ -142,8 +142,36 @@ internal sealed class SigningKeyRing : IDisposable
         return VerificationKeyLookup.Available;
     }
 
-    public bool Revoke(string keyId) =>
-        _keys.ContainsKey(keyId) && _runtimeRevocations.TryAdd(keyId, 0);
+    public bool Revoke(string keyId)
+    {
+        if (!_keys.ContainsKey(keyId))
+        {
+            return false;
+        }
+
+        _runtimeRevocations.TryAdd(keyId, 0);
+        return true;
+    }
+
+    public IReadOnlyList<SigningKeyStatus> GetStatuses(DateTimeOffset now) => _keys.Values
+        .OrderBy(static key => key.KeyId, StringComparer.Ordinal)
+        .Select(key => new SigningKeyStatus(
+            key.KeyId,
+            IsRevoked(key)
+                ? "revoked"
+                : now < key.NotBefore
+                    ? "not-yet-valid"
+                    : now < key.SignUntil
+                        ? "signing"
+                        : now < key.VerifyUntil
+                            ? "verify-only"
+                            : "retired",
+            key.SignUntil,
+            key.VerifyUntil,
+            key.GameId,
+            key.EnvironmentId,
+            key.CredentialKinds.Select(static kind => kind.ToString()).Order().ToArray()))
+        .ToArray();
 
     public void Dispose()
     {
@@ -210,6 +238,15 @@ internal sealed class SigningKeyRing : IDisposable
     }
 }
 
+internal sealed record SigningKeyStatus(
+    string KeyId,
+    string Status,
+    DateTimeOffset SignUntil,
+    DateTimeOffset VerifyUntil,
+    string? GameId,
+    string? EnvironmentId,
+    IReadOnlyList<string> CredentialKinds);
+
 internal sealed class SigningKey : IDisposable
 {
     private byte[]? _material;

src/FinalFactory.Rendezvous.Server/Sessions/SessionLeaseService.cs

@@ -55,6 +55,11 @@ internal sealed class SessionLeaseService(
         }
 
         AuthorizedPublisherContext context = authorized.Context;
+        if (!IsFallbackAllowed(context.Policy, request.DedicatedFallback))
+        {
+            return new(RendezvousErrorCode.Forbidden);
+        }
+
         string requestFingerprint = ComputeRegistrationFingerprint(request);
         string derivationSalt = capabilities.CreateDerivationSalt();
         string leaseToken = capabilities.DeriveCapability(
@@ -119,6 +124,7 @@ internal sealed class SessionLeaseService(
                 CurrentPlayers = request.Capacity.CurrentPlayers,
                 MaximumPlayers = request.Capacity.MaximumPlayers,
                 Metadata = request.Metadata,
+                DedicatedFallback = request.DedicatedFallback,
                 LeaseFingerprint = leaseFingerprint,
                 HostPresenceHandle = presenceHandle,
                 HostPresenceFingerprint = presenceFingerprint,
@@ -235,10 +241,14 @@ internal sealed class SessionLeaseService(
 
         StoredListing ownedListing = listing!;
         PublisherAuthorizationResult authorized = AuthorizeExisting(principal, ownedListing, request.Metadata);
-        if (!authorized.IsAllowed)
+        if (!authorized.IsAllowed || authorized.Context is null)
         {
             return new(MapAuthorization(authorized.Error));
         }
+        if (!IsFallbackAllowed(authorized.Context.Policy, request.DedicatedFallback))
+        {
+            return new(RendezvousErrorCode.Forbidden);
+        }
 
         capabilities.TryFingerprint(request.LeaseToken, out SecretFingerprint fingerprint);
         StoreResult<StoredListing> updated = store.UpdateListing(new(
@@ -250,7 +260,8 @@ internal sealed class SessionLeaseService(
             request.DisplayName,
             request.Capacity.CurrentPlayers,
             request.Capacity.MaximumPlayers,
-            request.Metadata), cancellationToken);
+            request.Metadata,
+            request.DedicatedFallback), cancellationToken);
         return updated.Succeeded
             ? new(RendezvousErrorCode.None, true)
             : new(updated.Code.ToContractError());
@@ -341,6 +352,9 @@ internal sealed class SessionLeaseService(
             metadata,
             clock.UtcNow);
 
+    private static bool IsFallbackAllowed(GamePolicy policy, NetworkEndpoint? fallback) =>
+        fallback is null || policy.FallbackPolicy == FallbackPolicyMode.DedicatedEndpointAllowed;
+
     private static RendezvousErrorCode ValidateRegistration(RegisterSessionRequest request)
     {
         RendezvousErrorCode version = ContractValidation.ValidateContractVersion(request.ContractVersion);
@@ -359,6 +373,8 @@ internal sealed class SessionLeaseService(
             || !Enum.IsDefined(request.Visibility)
             || !ContractValidation.IsCapacityValid(request.Capacity)
             || !ContractValidation.IsMetadataValid(request.Metadata)
+            || request.DedicatedFallback is not null
+                && !ContractValidation.IsNetworkEndpointValid(request.DedicatedFallback)
             ? RendezvousErrorCode.InvalidRequest
             : RendezvousErrorCode.None;
     }
@@ -375,6 +391,8 @@ internal sealed class SessionLeaseService(
             || !ContractValidation.IsDisplayNameValid(request.DisplayName)
             || !ContractValidation.IsCapacityValid(request.Capacity)
             || !ContractValidation.IsMetadataValid(request.Metadata)
+            || request.DedicatedFallback is not null
+                && !ContractValidation.IsNetworkEndpointValid(request.DedicatedFallback)
             ? RendezvousErrorCode.InvalidRequest
             : RendezvousErrorCode.None;
     }
@@ -424,6 +442,14 @@ internal sealed class SessionLeaseService(
             Metadata = request.Metadata
                 .OrderBy(static item => item.Key, StringComparer.Ordinal)
                 .ToDictionary(static item => item.Key, static item => item.Value, StringComparer.Ordinal),
+            DedicatedFallback = request.DedicatedFallback is null
+                ? null
+                : new NetworkEndpoint
+                {
+                    AddressFamily = request.DedicatedFallback.AddressFamily,
+                    Address = request.DedicatedFallback.Address,
+                    Port = request.DedicatedFallback.Port,
+                },
         };
         byte[] encoded = JsonSerializer.SerializeToUtf8Bytes(canonical, ContractJson.Options);
         byte[] digest = SHA256.HashData(encoded);

src/FinalFactory.Rendezvous.Server/State/EphemeralStateContracts.cs

@@ -29,6 +29,7 @@ internal sealed record EphemeralStoreOptions
     public int MaxListings { get; init; } = 25_000;
     public int MaxPresenceBindings { get; init; } = 25_000;
     public int MaxJoinAttempts { get; init; } = 10_000;
+    public int MaxOutcomeReports { get; init; } = 35_000;
     public int MaxReplayEntries { get; init; } = 30_000;
     public int MaxRevocations { get; init; } = 10_000;
     public int MaxIdempotencyEntries { get; init; } = 35_000;
@@ -45,6 +46,7 @@ internal sealed record EphemeralStoreOptions
         RequirePositive(MaxListings, nameof(MaxListings));
         RequirePositive(MaxPresenceBindings, nameof(MaxPresenceBindings));
         RequirePositive(MaxJoinAttempts, nameof(MaxJoinAttempts));
+        RequirePositive(MaxOutcomeReports, nameof(MaxOutcomeReports));
         RequirePositive(MaxReplayEntries, nameof(MaxReplayEntries));
         RequirePositive(MaxRevocations, nameof(MaxRevocations));
         RequirePositive(MaxIdempotencyEntries, nameof(MaxIdempotencyEntries));
@@ -173,6 +175,7 @@ internal sealed record ListingDefinition
     public required int CurrentPlayers { get; init; }
     public required int MaximumPlayers { get; init; }
     public required IReadOnlyDictionary<string, string> Metadata { get; init; }
+    public NetworkEndpoint? DedicatedFallback { get; init; }
     public required SecretFingerprint LeaseFingerprint { get; init; }
     public required MediationHandle HostPresenceHandle { get; init; }
     public required SecretFingerprint HostPresenceFingerprint { get; init; }
@@ -189,7 +192,17 @@ internal sealed record StoredListing
     public static ListingDefinition Freeze(ListingDefinition source) => source with
     {
         Metadata = source.Metadata.ToFrozenDictionary(StringComparer.Ordinal),
+        DedicatedFallback = CopyEndpoint(source.DedicatedFallback),
     };
+
+    internal static NetworkEndpoint? CopyEndpoint(NetworkEndpoint? endpoint) => endpoint is null
+        ? null
+        : new NetworkEndpoint
+        {
+            AddressFamily = endpoint.AddressFamily,
+            Address = endpoint.Address,
+            Port = endpoint.Port,
+        };
 }
 
 internal sealed record CreateListingCommand(
@@ -214,7 +227,8 @@ internal sealed record UpdateListingCommand(
     string DisplayName,
     int CurrentPlayers,
     int MaximumPlayers,
-    IReadOnlyDictionary<string, string> Metadata);
+    IReadOnlyDictionary<string, string> Metadata,
+    NetworkEndpoint? DedicatedFallback);
 
 internal sealed record DeleteListingCommand(
     SessionListingId ListingId,
@@ -257,6 +271,7 @@ internal sealed record CreateJoinAttemptCommand
     public required SecretFingerprint ClientCapabilityFingerprint { get; init; }
     public required SecretFingerprint ConnectionTicketFingerprint { get; init; }
     public required string CapabilityDerivationSalt { get; init; }
+    public NetworkEndpoint? DedicatedFallback { get; init; }
     public int ScopeAttemptLimit { get; init; } = int.MaxValue;
 
     public override string ToString() => "[CreateJoinAttemptCommand: credentials redacted]";
@@ -280,12 +295,15 @@ internal sealed record StoredJoinAttempt
     public required SecretFingerprint HostCapabilityFingerprint { get; init; }
     public required SecretFingerprint ClientCapabilityFingerprint { get; init; }
     public required SecretFingerprint ConnectionTicketFingerprint { get; init; }
+    public NetworkEndpoint? DedicatedFallback { get; init; }
     public required DateTimeOffset ExpiresAt { get; init; }
+    public required TimeSpan CreatedAtMonotonic { get; init; }
     public required DateTimeOffset ConnectionTicketExpiresAt { get; init; }
     public AttemptEndpointBinding? HostEndpoint { get; init; }
     public AttemptEndpointBinding? ClientEndpoint { get; init; }
     public required bool IntroductionConsumed { get; init; }
     public required bool ConnectionTicketConsumed { get; init; }
+    public required bool IsCancelled { get; init; }
 
     public override string ToString() => $"[StoredJoinAttempt {AttemptId}; credentials redacted]";
 }
@@ -315,6 +333,16 @@ internal sealed record CancelJoinAttemptCommand(
     JoinAttemptId AttemptId,
     SecretFingerprint ClientCapabilityFingerprint);
 
+internal sealed record ReportConnectionOutcomeCommand(
+    JoinAttemptId AttemptId,
+    SecretFingerprint ClientCapabilityFingerprint,
+    ConnectionOutcomeKind Outcome,
+    ConnectionElapsedBucket ElapsedBucket);
+
+internal sealed record StoredConnectionOutcome(
+    ConnectionOutcomeKind Outcome,
+    ConnectionElapsedBucket ElapsedBucket);
+
 internal sealed record ConsumeConnectionTicketCommand(
     JoinAttemptId AttemptId,
     SecretFingerprint ConnectionTicketFingerprint);
@@ -335,6 +363,8 @@ internal enum StoreResultCode
     Draining = 6,
     ReplayRejected = 7,
     ServiceUnavailable = 8,
+    StaleHost = 9,
+    IncompatibleProtocol = 10,
 }
 
 internal sealed record StoreResult<T>(StoreResultCode Code, T? Value = default, bool IsIdempotentReplay = false)
@@ -358,6 +388,7 @@ internal interface IEphemeralRendezvousStore
     StoreResult<StoredJoinAttempt> CreateJoinAttempt(CreateJoinAttemptCommand command, CancellationToken cancellationToken = default);
     StoreResult<IReadOnlyList<StoredJoinAttempt>> BrowseHostJoinAttempts(HostJoinAttemptQuery query, CancellationToken cancellationToken = default);
     StoreResult<bool> CancelJoinAttempt(CancelJoinAttemptCommand command, CancellationToken cancellationToken = default);
+    StoreResult<StoredConnectionOutcome> ReportConnectionOutcome(ReportConnectionOutcomeCommand command, CancellationToken cancellationToken = default);
     StoreResult<StoredJoinAttempt> BindAttemptEndpoint(BindAttemptEndpointCommand command, CancellationToken cancellationToken = default);
     StoreResult<IntroductionEndpoints> ConsumeIntroduction(MediationHandle handle, CancellationToken cancellationToken = default);
     StoreResult<bool> ConsumeConnectionTicket(ConsumeConnectionTicketCommand command, CancellationToken cancellationToken = default);

src/FinalFactory.Rendezvous.Server/State/InMemoryEphemeralRendezvousStore.cs

@@ -11,18 +11,36 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
     private readonly DateTimeOffset _wallOrigin;
     private readonly TimeSpan _monotonicOrigin;
     private readonly Dictionary<SessionListingId, ListingEntry> _listings = [];
+    private readonly Dictionary<string, int> _listingCountsByOwner = new(StringComparer.Ordinal);
+    private readonly PriorityQueue<DeadlineEntry<SessionListingId>, long> _listingExpiries = new();
+    private readonly HashSet<SessionListingId> _scheduledListingExpiries = [];
     private readonly Dictionary<LeaseId, SessionListingId> _leases = [];
     private readonly Dictionary<MediationHandle, SessionListingId> _presenceHandles = [];
     private readonly Dictionary<MediationHandle, PresenceEntry> _presence = [];
+    private readonly PriorityQueue<DeadlineEntry<MediationHandle>, long> _presenceExpiries = new();
+    private readonly HashSet<MediationHandle> _scheduledPresenceExpiries = [];
     private readonly Dictionary<JoinAttemptId, AttemptEntry> _attempts = [];
+    private readonly Dictionary<TenantScope, int> _attemptCountsByScope = [];
+    private readonly Dictionary<SessionListingId, HashSet<JoinAttemptId>> _attemptsByListing = [];
+    private readonly PriorityQueue<DeadlineEntry<JoinAttemptId>, long> _attemptExpiries = new();
+    private readonly Dictionary<JoinAttemptId, OutcomeReportEntry> _outcomeReports = [];
+    private readonly Dictionary<SessionListingId, HashSet<JoinAttemptId>> _outcomesByListing = [];
+    private readonly PriorityQueue<DeadlineEntry<JoinAttemptId>, long> _outcomeExpiries = new();
     private readonly Dictionary<MediationHandle, JoinAttemptId> _attemptHandles = [];
     private readonly Dictionary<string, IdempotencyEntry> _idempotency = new(StringComparer.Ordinal);
+    private readonly PriorityQueue<DeadlineEntry<string>, long> _idempotencyExpiries = new();
     private readonly Dictionary<string, TimeSpan> _replay = new(StringComparer.Ordinal);
+    private readonly PriorityQueue<DeadlineEntry<string>, long> _replayExpiries = new();
     private readonly Dictionary<string, TimeSpan> _revocations = new(StringComparer.Ordinal);
+    private readonly PriorityQueue<DeadlineEntry<string>, long> _revocationExpiries = new();
+    private readonly HashSet<string> _scheduledRevocationExpiries = new(StringComparer.Ordinal);
     private TimeSpan? _drainDeadline;
     private TimeSpan _nextUdpMaintenance;
     private long _maintenanceSweepCount;
+    private long _expiryChurn;
     private bool _available = true;
+    private EphemeralStoreSnapshot? _metricsSnapshot;
+    private TimeSpan _metricsSnapshotAt = TimeSpan.MinValue;
 
     public InMemoryEphemeralRendezvousStore(
         EphemeralStoreOptions options,
@@ -42,6 +60,22 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
     public Guid InstanceId { get; }
     internal long MaintenanceSweepCount => Interlocked.Read(ref _maintenanceSweepCount);
+    internal int ScheduledExpiryEntryCount
+    {
+        get
+        {
+            lock (_gate)
+            {
+                return _listingExpiries.Count
+                    + _presenceExpiries.Count
+                    + _attemptExpiries.Count
+                    + _outcomeExpiries.Count
+                    + _idempotencyExpiries.Count
+                    + _replayExpiries.Count
+                    + _revocationExpiries.Count;
+            }
+        }
+    }
 
     public bool IsAvailable
     {
@@ -65,6 +99,59 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         }
     }
 
+    internal EphemeralStoreSnapshot GetSnapshot()
+    {
+        lock (_gate)
+        {
+            TimeSpan now = _monotonicClock.Elapsed;
+            Cleanup(now);
+            EphemeralStoreSnapshot snapshot = CreateSnapshot();
+            _metricsSnapshot = snapshot;
+            _metricsSnapshotAt = now;
+            return snapshot;
+        }
+    }
+
+    internal int GetActiveJoinAttemptCountForDrain()
+    {
+        lock (_gate)
+        {
+            _expiryChurn += RemoveExpiredAttempts(_monotonicClock.Elapsed);
+            return _attempts.Count;
+        }
+    }
+
+    internal EphemeralStoreSnapshot GetMetricsSnapshot()
+    {
+        lock (_gate)
+        {
+            TimeSpan now = _monotonicClock.Elapsed;
+            if (_metricsSnapshot is null
+                || now < _metricsSnapshotAt
+                || now - _metricsSnapshotAt >= TimeSpan.FromMilliseconds(100))
+            {
+                Cleanup(now);
+                _metricsSnapshot = CreateSnapshot();
+                _metricsSnapshotAt = now;
+            }
+
+            return _metricsSnapshot;
+        }
+    }
+
+    private EphemeralStoreSnapshot CreateSnapshot() => new(
+        _listings.Count,
+        _presence.Count,
+        _attempts.Count,
+        _outcomeReports.Count,
+        _replay.Count,
+        _revocations.Count,
+        _idempotency.Count,
+        _maintenanceSweepCount,
+        _expiryChurn,
+        _available,
+        _drainDeadline.HasValue);
+
     public StoreResult<StoredListing> CreateListing(
         CreateListingCommand command,
         CancellationToken cancellationToken = default) => Atomic<StoredListing>(now =>
@@ -103,10 +190,8 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
         if (_listings.Count >= _options.MaxListings
             || _idempotency.Count >= _options.MaxIdempotencyEntries
-            || _listings.Values.Count(entry => string.Equals(
-                entry.Definition.OwnerSubject,
-                command.Listing.OwnerSubject,
-                StringComparison.Ordinal)) >= command.OwnerListingLimit)
+            || _listingCountsByOwner.GetValueOrDefault(command.Listing.OwnerSubject)
+                >= command.OwnerListingLimit)
         {
             return new(StoreResultCode.CapacityExceeded);
         }
@@ -125,12 +210,21 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             WallDeadline(now, _options.LeaseLifetime),
             version: 1);
         _listings.Add(frozen.ListingId, entry);
+        ScheduleMutableDeadline(
+            _listingExpiries,
+            _scheduledListingExpiries,
+            frozen.ListingId,
+            entry.LeaseDeadline);
+        _listingCountsByOwner[frozen.OwnerSubject] =
+            _listingCountsByOwner.GetValueOrDefault(frozen.OwnerSubject) + 1;
         _leases.Add(frozen.LeaseId, frozen.ListingId);
         _presenceHandles.Add(frozen.HostPresenceHandle, frozen.ListingId);
-        _idempotency.Add(idempotencyKey, new(
+        IdempotencyEntry idempotency = new(
             command.RequestFingerprint,
             frozen.ListingId,
-            now + _options.IdempotencyLifetime));
+            now + _options.IdempotencyLifetime);
+        _idempotency.Add(idempotencyKey, idempotency);
+        EnqueueDeadline(_idempotencyExpiries, idempotencyKey, idempotency.Deadline);
         return new(StoreResultCode.Success, Snapshot(entry));
     }, cancellationToken);
 
@@ -183,7 +277,9 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             || command.MaximumPlayers is <= 0 or > ContractLimits.SessionCapacityMaxPlayers
             || command.CurrentPlayers < 0
             || command.CurrentPlayers > command.MaximumPlayers
-            || !ContractValidation.IsMetadataValid(command.Metadata))
+            || !ContractValidation.IsMetadataValid(command.Metadata)
+            || command.DedicatedFallback is not null
+                && !ContractValidation.IsNetworkEndpointValid(command.DedicatedFallback))
         {
             throw new ArgumentException("Listing update invariants are invalid.", nameof(command));
         }
@@ -213,6 +309,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             CurrentPlayers = command.CurrentPlayers,
             MaximumPlayers = command.MaximumPlayers,
             Metadata = command.Metadata,
+            DedicatedFallback = command.DedicatedFallback,
         });
         entry.Version++;
         return new(StoreResultCode.Success, Snapshot(entry));
@@ -285,10 +382,20 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             return new(StoreResultCode.CapacityExceeded);
         }
 
-        _presence[command.Handle] = new(
+        bool isNewPresence = !_presence.ContainsKey(command.Handle);
+        PresenceEntry presence = new(
             command.PublicEndpoint,
             command.LocalEndpoint,
             now + _options.PresenceLifetime);
+        _presence[command.Handle] = presence;
+        if (isNewPresence)
+        {
+            ScheduleMutableDeadline(
+                _presenceExpiries,
+                _scheduledPresenceExpiries,
+                command.Handle,
+                presence.Deadline);
+        }
         return new(StoreResultCode.Success, Snapshot(entry));
     }, cancellationToken, eagerCleanup: false);
 
@@ -362,17 +469,28 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         }
 
         if (!_listings.TryGetValue(command.ListingId, out ListingEntry? listing)
-            || listing.Definition.Scope != command.Scope
-            || listing.Definition.ProtocolVersion != command.ProtocolVersion
-            || !_presence.ContainsKey(listing.Definition.HostPresenceHandle))
+            || listing.Definition.Scope != command.Scope)
         {
             return new(StoreResultCode.NotFound);
         }
+        if (listing.Definition.ProtocolVersion != command.ProtocolVersion)
+        {
+            return new(StoreResultCode.IncompatibleProtocol);
+        }
+        if (!_presence.ContainsKey(listing.Definition.HostPresenceHandle))
+        {
+            return new(StoreResultCode.StaleHost);
+        }
+
+        command = command with
+        {
+            DedicatedFallback = StoredListing.CopyEndpoint(listing.Definition.DedicatedFallback),
+        };
 
         if (_attempts.Count >= _options.MaxJoinAttempts
+            || _outcomeReports.Count >= _options.MaxOutcomeReports
             || _idempotency.Count >= _options.MaxIdempotencyEntries
-            || _attempts.Values.Count(entry => entry.Command.Scope == command.Scope)
-                >= command.ScopeAttemptLimit)
+            || _attemptCountsByScope.GetValueOrDefault(command.Scope) >= command.ScopeAttemptLimit)
         {
             return new(StoreResultCode.CapacityExceeded);
         }
@@ -384,14 +502,29 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
         AttemptEntry attempt = new(
             command,
+            now,
             now + _options.JoinAttemptLifetime,
             WallDeadline(now, _options.JoinAttemptLifetime));
         _attempts.Add(command.AttemptId, attempt);
+        AddToIndex(_attemptsByListing, command.ListingId, command.AttemptId);
+        _attemptCountsByScope[command.Scope] =
+            _attemptCountsByScope.GetValueOrDefault(command.Scope) + 1;
+        EnqueueDeadline(_attemptExpiries, command.AttemptId, attempt.Deadline);
+        OutcomeReportEntry outcome = new(
+            command.ListingId,
+            command.ClientSubject,
+            command.ClientCapabilityFingerprint,
+            now + _options.JoinAttemptLifetime + _options.IdempotencyLifetime);
+        _outcomeReports.Add(command.AttemptId, outcome);
+        AddToIndex(_outcomesByListing, command.ListingId, command.AttemptId);
+        EnqueueDeadline(_outcomeExpiries, command.AttemptId, outcome.Deadline);
         _attemptHandles.Add(command.MediationHandle, command.AttemptId);
-        _idempotency.Add(idempotencyKey, new(
+        IdempotencyEntry idempotency = new(
             command.RequestFingerprint,
             command.AttemptId,
-            now + _options.IdempotencyLifetime));
+            now + _options.IdempotencyLifetime);
+        _idempotency.Add(idempotencyKey, idempotency);
+        EnqueueDeadline(_idempotencyExpiries, idempotencyKey, idempotency.Deadline);
         return new(StoreResultCode.Success, Snapshot(attempt));
     }, cancellationToken);
 
@@ -420,7 +553,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
         IReadOnlyList<StoredJoinAttempt> attempts = _attempts.Values
             .Where(entry => entry.Command.ListingId == query.ListingId
-                && !entry.IntroductionConsumed
+                && (!entry.IntroductionConsumed || entry.IsCancelled)
                 && (!query.AfterAttemptId.HasValue
                     || entry.Command.AttemptId.Value.CompareTo(query.AfterAttemptId.Value.Value) > 0))
             .OrderBy(static entry => entry.Command.AttemptId.Value)
@@ -451,15 +584,51 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             return new(StoreResultCode.NotFound);
         }
 
-        if (attempt.IntroductionConsumed)
+        if (attempt.IsCancelled)
         {
-            return new(StoreResultCode.Conflict);
+            return new(StoreResultCode.Success, true, true);
         }
 
-        RemoveAttempt(command.AttemptId);
+        attempt.IsCancelled = true;
         return new(StoreResultCode.Success, true);
     }, cancellationToken);
 
+    public StoreResult<StoredConnectionOutcome> ReportConnectionOutcome(
+        ReportConnectionOutcomeCommand command,
+        CancellationToken cancellationToken = default) => Atomic<StoredConnectionOutcome>(_ =>
+    {
+        ArgumentNullException.ThrowIfNull(command);
+        if (command.AttemptId.Value == Guid.Empty
+            || !command.ClientCapabilityFingerprint.IsValid
+            || !ContractValidation.IsReportableConnectionOutcome(command.Outcome)
+            || !Enum.IsDefined(command.ElapsedBucket))
+        {
+            throw new ArgumentException("Connection outcome invariants are invalid.", nameof(command));
+        }
+
+        if (!_available)
+        {
+            return new(StoreResultCode.ServiceUnavailable);
+        }
+
+        if (!_outcomeReports.TryGetValue(command.AttemptId, out OutcomeReportEntry? entry)
+            || entry.ClientCapabilityFingerprint != command.ClientCapabilityFingerprint)
+        {
+            return new(StoreResultCode.NotFound);
+        }
+
+        StoredConnectionOutcome reported = new(command.Outcome, command.ElapsedBucket);
+        if (entry.Outcome is not null)
+        {
+            return entry.Outcome == reported
+                ? new(StoreResultCode.Success, entry.Outcome, true)
+                : new(StoreResultCode.ReplayRejected);
+        }
+
+        entry.Outcome = reported;
+        return new(StoreResultCode.Success, reported);
+    }, cancellationToken);
+
     public StoreResult<StoredJoinAttempt> BindAttemptEndpoint(
         BindAttemptEndpointCommand command,
         CancellationToken cancellationToken = default) => Atomic<StoredJoinAttempt>(now =>
@@ -480,7 +649,8 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
         if (!_attemptHandles.TryGetValue(command.Handle, out JoinAttemptId attemptId)
             || !_attempts.TryGetValue(attemptId, out AttemptEntry? attempt)
-            || attempt.Deadline <= now)
+            || attempt.Deadline <= now
+            || attempt.IsCancelled)
         {
             return new(StoreResultCode.NotFound);
         }
@@ -532,7 +702,8 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
         if (!_attemptHandles.TryGetValue(handle, out JoinAttemptId attemptId)
             || !_attempts.TryGetValue(attemptId, out AttemptEntry? attempt)
-            || attempt.Deadline <= now)
+            || attempt.Deadline <= now
+            || attempt.IsCancelled)
         {
             return new(StoreResultCode.NotFound);
         }
@@ -590,6 +761,11 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             return new(StoreResultCode.Conflict);
         }
 
+        if (attempt.IsCancelled)
+        {
+            return new(StoreResultCode.Conflict);
+        }
+
         if (!attempt.TicketDeadline.HasValue || attempt.TicketDeadline.Value <= now)
         {
             return new(StoreResultCode.Expired);
@@ -632,7 +808,9 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             throw new ArgumentOutOfRangeException(nameof(consumption), "Replay lifetime exceeds the configured ceiling.");
         }
 
-        _replay.Add(key, now + lifetime);
+        TimeSpan deadline = now + lifetime;
+        _replay.Add(key, deadline);
+        EnqueueDeadline(_replayExpiries, key, deadline);
         return new(StoreResultCode.Success, true);
     }, cancellationToken);
 
@@ -665,7 +843,28 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             return new(StoreResultCode.CapacityExceeded);
         }
 
-        _revocations[subject] = now + lifetime;
+        int activeResourcesBefore = _listings.Count
+            + _presence.Count
+            + _attempts.Count
+            + _outcomeReports.Count;
+        TimeSpan deadline = now + lifetime;
+        bool isNewRevocation = !_revocations.TryGetValue(subject, out TimeSpan existingDeadline);
+        if (!isNewRevocation && existingDeadline > deadline)
+        {
+            // A repeated operator action may extend protection but cannot silently
+            // shorten an already-authoritative security revocation.
+            deadline = existingDeadline;
+        }
+
+        _revocations[subject] = deadline;
+        if (isNewRevocation)
+        {
+            ScheduleMutableDeadline(
+                _revocationExpiries,
+                _scheduledRevocationExpiries,
+                subject,
+                deadline);
+        }
         SessionListingId[] listings = _listings
             .Where(item => string.Equals(item.Value.Definition.OwnerSubject, subject, StringComparison.Ordinal))
             .Select(static item => item.Key)
@@ -674,6 +873,10 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             .Where(item => string.Equals(item.Value.Command.ClientSubject, subject, StringComparison.Ordinal))
             .Select(static item => item.Key)
             .ToArray();
+        JoinAttemptId[] outcomeReports = _outcomeReports
+            .Where(item => string.Equals(item.Value.ClientSubject, subject, StringComparison.Ordinal))
+            .Select(static item => item.Key)
+            .ToArray();
         foreach (SessionListingId listingId in listings)
         {
             RemoveListing(listingId);
@@ -683,8 +886,16 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         {
             RemoveAttempt(attemptId);
         }
+        foreach (JoinAttemptId attemptId in outcomeReports)
+        {
+            RemoveOutcome(attemptId);
+        }
 
-        return new(StoreResultCode.Success, listings.Length + attempts.Length);
+        int activeResourcesAfter = _listings.Count
+            + _presence.Count
+            + _attempts.Count
+            + _outcomeReports.Count;
+        return new(StoreResultCode.Success, activeResourcesBefore - activeResourcesAfter);
     }, cancellationToken);
 
     public void BeginDrain(CancellationToken cancellationToken = default)
@@ -696,6 +907,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             if (!_drainDeadline.HasValue)
             {
                 _drainDeadline = _monotonicClock.Elapsed + _options.GracefulDrainLifetime;
+                _metricsSnapshot = null;
             }
         }
     }
@@ -706,6 +918,7 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         {
             _available = false;
             ClearActiveState();
+            _metricsSnapshot = null;
         }
     }
 
@@ -729,7 +942,9 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
                 _nextUdpMaintenance = now + UdpMaintenanceInterval;
             }
 
-            return operation(now);
+            StoreResult<T> result = operation(now);
+            _metricsSnapshot = null;
+            return result;
         }
     }
 
@@ -766,51 +981,42 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             ClearActiveState();
         }
 
-        RemoveExpired(_revocations, now);
-        RemoveExpired(_replay, now);
-        foreach (string key in _idempotency
-                     .Where(item => item.Value.Deadline <= now)
-                     .Select(static item => item.Key)
-                     .ToArray())
-        {
-            _idempotency.Remove(key);
-        }
-
-        foreach (MediationHandle handle in _presence
-                     .Where(item => item.Value.Deadline <= now)
-                     .Select(static item => item.Key)
-                     .ToArray())
-        {
-            _presence.Remove(handle);
-        }
-
-        foreach (JoinAttemptId attemptId in _attempts
-                     .Where(item => item.Value.Deadline <= now)
-                     .Select(static item => item.Key)
-                     .ToArray())
-        {
-            RemoveAttempt(attemptId);
-        }
-
-        foreach (SessionListingId listingId in _listings
-                     .Where(item => item.Value.LeaseDeadline <= now)
-                     .Select(static item => item.Key)
-                     .ToArray())
-        {
-            RemoveListing(listingId);
-        }
+        _expiryChurn += RemoveExpiredMutableDeadlines(
+            _revocations,
+            _revocationExpiries,
+            _scheduledRevocationExpiries,
+            now);
+        _expiryChurn += RemoveExpiredDeadlines(_replay, _replayExpiries, now);
+        _expiryChurn += RemoveExpiredIdempotency(now);
+        _expiryChurn += RemoveExpiredPresence(now);
+        _expiryChurn += RemoveExpiredAttempts(now);
+        _expiryChurn += RemoveExpiredOutcomes(now);
+        _expiryChurn += RemoveExpiredListings(now);
     }
 
     private void ClearActiveState()
     {
         _listings.Clear();
+        _listingCountsByOwner.Clear();
+        _listingExpiries.Clear();
+        _scheduledListingExpiries.Clear();
         _leases.Clear();
         _presenceHandles.Clear();
         _presence.Clear();
+        _presenceExpiries.Clear();
+        _scheduledPresenceExpiries.Clear();
         _attempts.Clear();
+        _attemptCountsByScope.Clear();
+        _attemptsByListing.Clear();
+        _attemptExpiries.Clear();
+        _outcomeReports.Clear();
+        _outcomesByListing.Clear();
+        _outcomeExpiries.Clear();
         _attemptHandles.Clear();
         _idempotency.Clear();
+        _idempotencyExpiries.Clear();
         _replay.Clear();
+        _replayExpiries.Clear();
     }
 
     private void RemoveListing(SessionListingId listingId)
@@ -821,14 +1027,23 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         }
 
         _leases.Remove(listing.Definition.LeaseId);
+        DecrementCount(_listingCountsByOwner, listing.Definition.OwnerSubject);
         _presenceHandles.Remove(listing.Definition.HostPresenceHandle);
         _presence.Remove(listing.Definition.HostPresenceHandle);
-        foreach (JoinAttemptId attemptId in _attempts
-                     .Where(item => item.Value.Command.ListingId == listingId)
-                     .Select(static item => item.Key)
-                     .ToArray())
+        if (_attemptsByListing.TryGetValue(listingId, out HashSet<JoinAttemptId>? attempts))
         {
-            RemoveAttempt(attemptId);
+            foreach (JoinAttemptId attemptId in attempts.ToArray())
+            {
+                RemoveAttempt(attemptId);
+            }
+        }
+
+        if (_outcomesByListing.TryGetValue(listingId, out HashSet<JoinAttemptId>? outcomes))
+        {
+            foreach (JoinAttemptId attemptId in outcomes.ToArray())
+            {
+                RemoveOutcome(attemptId);
+            }
         }
     }
 
@@ -837,9 +1052,260 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         if (_attempts.Remove(attemptId, out AttemptEntry? attempt))
         {
             _attemptHandles.Remove(attempt.Command.MediationHandle);
+            DecrementCount(_attemptCountsByScope, attempt.Command.Scope);
+            RemoveFromIndex(_attemptsByListing, attempt.Command.ListingId, attemptId);
         }
     }
 
+    private void RemoveOutcome(JoinAttemptId attemptId)
+    {
+        if (_outcomeReports.Remove(attemptId, out OutcomeReportEntry? outcome))
+        {
+            RemoveFromIndex(_outcomesByListing, outcome.ListingId, attemptId);
+        }
+    }
+
+    private static void AddToIndex<TKey>(
+        Dictionary<TKey, HashSet<JoinAttemptId>> index,
+        TKey key,
+        JoinAttemptId attemptId)
+        where TKey : notnull
+    {
+        if (!index.TryGetValue(key, out HashSet<JoinAttemptId>? values))
+        {
+            values = [];
+            index.Add(key, values);
+        }
+
+        values.Add(attemptId);
+    }
+
+    private static void RemoveFromIndex<TKey>(
+        Dictionary<TKey, HashSet<JoinAttemptId>> index,
+        TKey key,
+        JoinAttemptId attemptId)
+        where TKey : notnull
+    {
+        if (index.TryGetValue(key, out HashSet<JoinAttemptId>? values)
+            && values.Remove(attemptId)
+            && values.Count == 0)
+        {
+            index.Remove(key);
+        }
+    }
+
+    private static void DecrementCount<TKey>(Dictionary<TKey, int> counts, TKey key)
+        where TKey : notnull
+    {
+        int remaining = counts[key] - 1;
+        if (remaining == 0)
+        {
+            counts.Remove(key);
+        }
+        else
+        {
+            counts[key] = remaining;
+        }
+    }
+
+    private int RemoveExpiredAttempts(TimeSpan now)
+    {
+        int removed = 0;
+        while (_attemptExpiries.TryPeek(
+                   out DeadlineEntry<JoinAttemptId> candidate,
+                   out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            _attemptExpiries.Dequeue();
+            if (_attempts.TryGetValue(candidate.Key, out AttemptEntry? current)
+                && current.Deadline == candidate.Deadline)
+            {
+                RemoveAttempt(candidate.Key);
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private int RemoveExpiredListings(TimeSpan now)
+    {
+        int removed = 0;
+        while (_listingExpiries.TryPeek(
+                   out DeadlineEntry<SessionListingId> candidate,
+                   out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            _listingExpiries.Dequeue();
+            _scheduledListingExpiries.Remove(candidate.Key);
+            if (!_listings.TryGetValue(candidate.Key, out ListingEntry? current))
+            {
+                continue;
+            }
+
+            if (current.LeaseDeadline > now)
+            {
+                ScheduleMutableDeadline(
+                    _listingExpiries,
+                    _scheduledListingExpiries,
+                    candidate.Key,
+                    current.LeaseDeadline);
+            }
+            else
+            {
+                RemoveListing(candidate.Key);
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private int RemoveExpiredPresence(TimeSpan now)
+    {
+        int removed = 0;
+        while (_presenceExpiries.TryPeek(
+                   out DeadlineEntry<MediationHandle> candidate,
+                   out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            _presenceExpiries.Dequeue();
+            _scheduledPresenceExpiries.Remove(candidate.Key);
+            if (!_presence.TryGetValue(candidate.Key, out PresenceEntry? current))
+            {
+                continue;
+            }
+
+            if (current.Deadline > now)
+            {
+                ScheduleMutableDeadline(
+                    _presenceExpiries,
+                    _scheduledPresenceExpiries,
+                    candidate.Key,
+                    current.Deadline);
+            }
+            else if (_presence.Remove(candidate.Key))
+            {
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private int RemoveExpiredOutcomes(TimeSpan now)
+    {
+        int removed = 0;
+        while (_outcomeExpiries.TryPeek(
+                   out DeadlineEntry<JoinAttemptId> candidate,
+                   out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            _outcomeExpiries.Dequeue();
+            if (_outcomeReports.TryGetValue(candidate.Key, out OutcomeReportEntry? current)
+                && current.Deadline == candidate.Deadline)
+            {
+                RemoveOutcome(candidate.Key);
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private int RemoveExpiredIdempotency(TimeSpan now)
+    {
+        int removed = 0;
+        while (_idempotencyExpiries.TryPeek(
+                   out DeadlineEntry<string> candidate,
+                   out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            _idempotencyExpiries.Dequeue();
+            if (_idempotency.TryGetValue(candidate.Key, out IdempotencyEntry? current)
+                && current.Deadline == candidate.Deadline
+                && _idempotency.Remove(candidate.Key))
+            {
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private static int RemoveExpiredDeadlines<TKey>(
+        Dictionary<TKey, TimeSpan> entries,
+        PriorityQueue<DeadlineEntry<TKey>, long> expiries,
+        TimeSpan now)
+        where TKey : notnull
+    {
+        int removed = 0;
+        while (expiries.TryPeek(out DeadlineEntry<TKey> candidate, out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            expiries.Dequeue();
+            if (entries.TryGetValue(candidate.Key, out TimeSpan current)
+                && current == candidate.Deadline
+                && entries.Remove(candidate.Key))
+            {
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private static int RemoveExpiredMutableDeadlines<TKey>(
+        Dictionary<TKey, TimeSpan> entries,
+        PriorityQueue<DeadlineEntry<TKey>, long> expiries,
+        HashSet<TKey> scheduled,
+        TimeSpan now)
+        where TKey : notnull
+    {
+        int removed = 0;
+        while (expiries.TryPeek(out DeadlineEntry<TKey> candidate, out long deadlineTicks)
+               && deadlineTicks <= now.Ticks)
+        {
+            expiries.Dequeue();
+            scheduled.Remove(candidate.Key);
+            if (!entries.TryGetValue(candidate.Key, out TimeSpan current))
+            {
+                continue;
+            }
+
+            if (current > now)
+            {
+                ScheduleMutableDeadline(expiries, scheduled, candidate.Key, current);
+            }
+            else if (entries.Remove(candidate.Key))
+            {
+                removed++;
+            }
+        }
+
+        return removed;
+    }
+
+    private static void ScheduleMutableDeadline<TKey>(
+        PriorityQueue<DeadlineEntry<TKey>, long> expiries,
+        HashSet<TKey> scheduled,
+        TKey key,
+        TimeSpan deadline)
+        where TKey : notnull
+    {
+        if (scheduled.Add(key))
+        {
+            EnqueueDeadline(expiries, key, deadline);
+        }
+    }
+
+    private static void EnqueueDeadline<TKey>(
+        PriorityQueue<DeadlineEntry<TKey>, long> expiries,
+        TKey key,
+        TimeSpan deadline)
+        where TKey : notnull =>
+        expiries.Enqueue(new(key, deadline), deadline.Ticks);
+
     private bool HandleExists(MediationHandle handle) =>
         _presenceHandles.ContainsKey(handle) || _attemptHandles.ContainsKey(handle);
 
@@ -868,25 +1334,17 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         HostCapabilityFingerprint = entry.Command.HostCapabilityFingerprint,
         ClientCapabilityFingerprint = entry.Command.ClientCapabilityFingerprint,
         ConnectionTicketFingerprint = entry.Command.ConnectionTicketFingerprint,
+        DedicatedFallback = StoredListing.CopyEndpoint(entry.Command.DedicatedFallback),
+        CreatedAtMonotonic = entry.CreatedAtMonotonic,
         ExpiresAt = entry.WallExpiresAt,
         ConnectionTicketExpiresAt = entry.TicketWallExpiresAt ?? default,
         HostEndpoint = entry.HostEndpoint,
         ClientEndpoint = entry.ClientEndpoint,
         IntroductionConsumed = entry.IntroductionConsumed,
         ConnectionTicketConsumed = entry.ConnectionTicketConsumed,
+        IsCancelled = entry.IsCancelled,
     };
 
-    private static void RemoveExpired(Dictionary<string, TimeSpan> entries, TimeSpan now)
-    {
-        foreach (string key in entries
-                     .Where(item => item.Value <= now)
-                     .Select(static item => item.Key)
-                     .ToArray())
-        {
-            entries.Remove(key);
-        }
-    }
-
     private static void ValidateListing(ListingDefinition listing)
     {
         ArgumentNullException.ThrowIfNull(listing);
@@ -906,6 +1364,8 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             || listing.CurrentPlayers < 0
             || listing.CurrentPlayers > listing.MaximumPlayers
             || !ContractValidation.IsMetadataValid(listing.Metadata)
+            || listing.DedicatedFallback is not null
+                && !ContractValidation.IsNetworkEndpointValid(listing.DedicatedFallback)
             || !listing.LeaseFingerprint.IsValid
             || !listing.HostPresenceFingerprint.IsValid
             || !IsDerivationSaltValid(listing.CapabilityDerivationSalt))
@@ -946,6 +1406,8 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
             || !command.HostCapabilityFingerprint.IsValid
             || !command.ClientCapabilityFingerprint.IsValid
             || !command.ConnectionTicketFingerprint.IsValid
+            || command.DedicatedFallback is not null
+                && !ContractValidation.IsNetworkEndpointValid(command.DedicatedFallback)
             || !IsDerivationSaltValid(command.CapabilityDerivationSalt)
             || command.ScopeAttemptLimit <= 0)
         {
@@ -1005,10 +1467,12 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
 
     private sealed class AttemptEntry(
         CreateJoinAttemptCommand command,
+        TimeSpan createdAtMonotonic,
         TimeSpan deadline,
         DateTimeOffset wallExpiresAt)
     {
         public CreateJoinAttemptCommand Command { get; } = command;
+        public TimeSpan CreatedAtMonotonic { get; } = createdAtMonotonic;
         public SecretFingerprint HostCapabilityFingerprint { get; } = command.HostCapabilityFingerprint;
         public SecretFingerprint ClientCapabilityFingerprint { get; } = command.ClientCapabilityFingerprint;
         public SecretFingerprint ConnectionTicketFingerprint { get; } = command.ConnectionTicketFingerprint;
@@ -1020,6 +1484,23 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         public AttemptEndpointBinding? ClientEndpoint { get; set; }
         public bool IntroductionConsumed { get; set; }
         public bool ConnectionTicketConsumed { get; set; }
+        public bool IsCancelled { get; set; }
+    }
+
+    private readonly record struct DeadlineEntry<TKey>(TKey Key, TimeSpan Deadline)
+        where TKey : notnull;
+
+    private sealed class OutcomeReportEntry(
+        SessionListingId listingId,
+        string clientSubject,
+        SecretFingerprint clientCapabilityFingerprint,
+        TimeSpan deadline)
+    {
+        public SessionListingId ListingId { get; } = listingId;
+        public string ClientSubject { get; } = clientSubject;
+        public SecretFingerprint ClientCapabilityFingerprint { get; } = clientCapabilityFingerprint;
+        public TimeSpan Deadline { get; } = deadline;
+        public StoredConnectionOutcome? Outcome { get; set; }
     }
 
     private sealed record IdempotencyEntry(
@@ -1027,3 +1508,16 @@ internal sealed class InMemoryEphemeralRendezvousStore : IEphemeralRendezvousSto
         object ResourceId,
         TimeSpan Deadline);
 }
+
+internal sealed record EphemeralStoreSnapshot(
+    int ActiveListings,
+    int FreshPresenceBindings,
+    int ActiveJoinAttempts,
+    int RetainedOutcomeReports,
+    int ReplayMarkers,
+    int PrincipalRevocations,
+    int IdempotencyEntries,
+    long MaintenanceSweeps,
+    long ExpiryChurn,
+    bool IsAvailable,
+    bool IsDraining);

src/FinalFactory.Rendezvous.Server/State/StoreResultMapping.cs

@@ -13,6 +13,8 @@ internal static class StoreResultMapping
         StoreResultCode.Conflict => RendezvousErrorCode.Conflict,
         StoreResultCode.CapacityExceeded => RendezvousErrorCode.CapacityExceeded,
         StoreResultCode.ReplayRejected => RendezvousErrorCode.ReplayRejected,
+        StoreResultCode.StaleHost => RendezvousErrorCode.StaleHost,
+        StoreResultCode.IncompatibleProtocol => RendezvousErrorCode.IncompatibleProtocol,
         StoreResultCode.Draining or StoreResultCode.ServiceUnavailable =>
             RendezvousErrorCode.ServiceUnavailable,
         _ => RendezvousErrorCode.InternalError,

src/FinalFactory.Rendezvous.Server/Transport/NatMediationProcessor.cs

@@ -1,7 +1,10 @@
+using System.Diagnostics;
 using System.Net;
 using System.Net.Sockets;
 using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.JoinAttempts;
+using FinalFactory.Rendezvous.Server.Observability;
 using FinalFactory.Rendezvous.Server.Sessions;
 using FinalFactory.Rendezvous.Server.State;
 
@@ -17,7 +20,7 @@ internal sealed record NatIntroductionPlan(
     IPEndPoint HostPublic,
     IPEndPoint ClientLocal,
     IPEndPoint ClientPublic,
-    string ConnectionTicket)
+    string IntroductionToken)
 {
     public override string ToString() => "[NatIntroductionPlan: endpoints and ticket redacted]";
 }
@@ -36,7 +39,10 @@ internal enum NatMediationResult
 internal sealed class NatMediationProcessor(
     IEphemeralRendezvousStore store,
     ISessionCapabilityService capabilities,
-    JoinAttemptService joinAttempts)
+    JoinAttemptService joinAttempts,
+    AbuseProtectionService? abuseProtection = null,
+    RendezvousTelemetry? telemetry = null,
+    IMonotonicClock? monotonicClock = null)
 {
     public NatMediationResult ProcessDatagram(
         ReadOnlySpan<byte> encoded,
@@ -44,6 +50,49 @@ internal sealed class NatMediationProcessor(
         INatIntroductionSink introductionSink,
         CancellationToken cancellationToken = default)
     {
+        if (!TryAcceptIngress(observedPublicEndpoint, "frozen"))
+        {
+            return NatMediationResult.Dropped;
+        }
+
+        return ProcessDatagramAfterIngress(
+            encoded,
+            observedPublicEndpoint,
+            introductionSink,
+            cancellationToken);
+    }
+
+    internal bool TryAcceptIngress(IPEndPoint observedPublicEndpoint, string operation) =>
+        abuseProtection is null
+        || abuseProtection.TryAcceptUdpIngress(observedPublicEndpoint.Address, operation);
+
+    internal NatMediationResult ProcessDatagramAfterIngress(
+        ReadOnlySpan<byte> encoded,
+        IPEndPoint observedPublicEndpoint,
+        INatIntroductionSink introductionSink,
+        CancellationToken cancellationToken = default)
+    {
+        long started = Stopwatch.GetTimestamp();
+        using Activity? activity = telemetry?.StartActivity("UDP frozen", ActivityKind.Server);
+        NatMediationResult result = ProcessDatagramCore(
+            encoded,
+            observedPublicEndpoint,
+            introductionSink,
+            cancellationToken);
+        telemetry?.RecordUdp(
+            "frozen",
+            result.ToString(),
+            Stopwatch.GetElapsedTime(started).TotalMilliseconds);
+        return result;
+    }
+
+    private NatMediationResult ProcessDatagramCore(
+        ReadOnlySpan<byte> encoded,
+        IPEndPoint observedPublicEndpoint,
+        INatIntroductionSink introductionSink,
+        CancellationToken cancellationToken)
+    {
+
         if (!RendezvousUdpCodec.TryDecode(encoded, out PresenceDatagram? datagram, out _)
             || datagram is null
             || datagram.Capability.Length != ContractLimits.DerivedCredentialCharacters
@@ -63,7 +112,7 @@ internal sealed class NatMediationProcessor(
             return NatMediationResult.Dropped;
         }
 
-        NatMediationResult result = ProcessRequest(
+        NatMediationResult result = ProcessRequestCore(
             claimedLocalEndpoint,
             observedPublicEndpoint,
             NatPunchRequestTokenCodec.Encode(role, datagram.MediationHandle, datagram.Capability),
@@ -76,7 +125,7 @@ internal sealed class NatMediationProcessor(
             return result;
         }
 
-        return ProcessRequest(
+        return ProcessRequestCore(
             claimedLocalEndpoint,
             observedPublicEndpoint,
             NatPunchRequestTokenCodec.Encode(
@@ -98,6 +147,49 @@ internal sealed class NatMediationProcessor(
         ArgumentNullException.ThrowIfNull(observedPublicEndpoint);
         ArgumentNullException.ThrowIfNull(introductionSink);
 
+        if (!TryAcceptIngress(observedPublicEndpoint, "litenet-or-invalid"))
+        {
+            return NatMediationResult.Dropped;
+        }
+
+        return ProcessRequestAfterIngress(
+            claimedLocalEndpoint,
+            observedPublicEndpoint,
+            token,
+            introductionSink,
+            cancellationToken);
+    }
+
+    internal NatMediationResult ProcessRequestAfterIngress(
+        IPEndPoint claimedLocalEndpoint,
+        IPEndPoint observedPublicEndpoint,
+        string token,
+        INatIntroductionSink introductionSink,
+        CancellationToken cancellationToken = default)
+    {
+        long started = Stopwatch.GetTimestamp();
+        using Activity? activity = telemetry?.StartActivity("UDP litenet", ActivityKind.Server);
+        NatMediationResult result = ProcessRequestCore(
+            claimedLocalEndpoint,
+            observedPublicEndpoint,
+            token,
+            introductionSink,
+            cancellationToken);
+        telemetry?.RecordUdp(
+            "litenet",
+            result.ToString(),
+            Stopwatch.GetElapsedTime(started).TotalMilliseconds);
+        return result;
+    }
+
+    private NatMediationResult ProcessRequestCore(
+        IPEndPoint claimedLocalEndpoint,
+        IPEndPoint observedPublicEndpoint,
+        string token,
+        INatIntroductionSink introductionSink,
+        CancellationToken cancellationToken)
+    {
+
         if (!NatPunchRequestTokenCodec.TryDecode(token, out NatPunchRequestToken? request)
             || request is null
             || !TryCreateObservedEndpoint(observedPublicEndpoint, out ObservedEndpoint publicEndpoint)
@@ -106,6 +198,17 @@ internal sealed class NatMediationProcessor(
             return NatMediationResult.Dropped;
         }
 
+        string operation = request.Role.ToString();
+        if (abuseProtection is not null
+            && !abuseProtection.TryAcceptUdpIdentity(
+                operation,
+                observedPublicEndpoint.Address,
+                request.Capability,
+                request.MediationHandle.ToString()))
+        {
+            return NatMediationResult.Dropped;
+        }
+
         ObservedEndpoint? localEndpoint = TryCreatePrivateCandidate(
             claimedLocalEndpoint,
             publicEndpoint.AddressFamily,
@@ -185,7 +288,15 @@ internal sealed class NatMediationProcessor(
 
         try
         {
-            introductionSink.Introduce(CreatePlan(consumed.Value, ticket.Value.Ticket));
+            introductionSink.Introduce(CreatePlan(consumed.Value, ticket.Value));
+            if (telemetry is not null && monotonicClock is not null)
+            {
+                telemetry.RecordPairingLatency(Math.Max(
+                    0,
+                    (monotonicClock.Elapsed - consumed.Value.Attempt.CreatedAtMonotonic)
+                    .TotalMilliseconds));
+            }
+
             return NatMediationResult.Introduced;
         }
         catch (Exception exception) when (exception is SocketException
@@ -198,7 +309,7 @@ internal sealed class NatMediationProcessor(
 
     private static NatIntroductionPlan CreatePlan(
         IntroductionEndpoints endpoints,
-        string connectionTicket)
+        ConnectionTicketGrant ticket)
     {
         IPEndPoint hostPublic = ToIpEndpoint(endpoints.Host.PublicEndpoint);
         IPEndPoint clientPublic = ToIpEndpoint(endpoints.Client.PublicEndpoint);
@@ -209,7 +320,12 @@ internal sealed class NatMediationProcessor(
         IPEndPoint clientLocal = sameNat && endpoints.Client.LocalEndpoint is { } clientCandidate
             ? ToIpEndpoint(clientCandidate)
             : clientPublic;
-        return new(hostLocal, hostPublic, clientLocal, clientPublic, connectionTicket);
+        return new(
+            hostLocal,
+            hostPublic,
+            clientLocal,
+            clientPublic,
+            ticket.Ticket);
     }
 
     private static bool TryCreateObservedEndpoint(

src/FinalFactory.Rendezvous.Server/Transport/UdpMediatorService.cs

@@ -155,7 +155,7 @@ internal sealed partial class UdpMediatorService : BackgroundService
             plan.HostPublic,
             plan.ClientLocal,
             plan.ClientPublic,
-            plan.ConnectionTicket);
+            plan.IntroductionToken);
     }
 
     private sealed class RendezvousPacketLayer(NatMediationProcessor processor) : PacketLayerBase(0)
@@ -172,12 +172,21 @@ internal sealed partial class UdpMediatorService : BackgroundService
             bool isFrozenEnvelope = length >= 2
                 && data[0] == RendezvousUdpCodec.MagicFirst
                 && data[1] == RendezvousUdpCodec.MagicSecond;
+            if (!processor.TryAcceptIngress(
+                    endPoint,
+                    isFrozenEnvelope ? "frozen" : "litenet-or-invalid"))
+            {
+                Drop(ref length);
+                return;
+            }
+
             INatIntroductionSink? sink = _sink;
             if (isFrozenEnvelope)
             {
                 if (sink is not null)
                 {
-                    _ = processor.ProcessDatagram(data.AsSpan(0, length), endPoint, sink);
+                    _ = processor.ProcessDatagramAfterIngress(
+                        data.AsSpan(0, length), endPoint, sink);
                 }
             }
             else if (sink is not null
@@ -188,7 +197,8 @@ internal sealed partial class UdpMediatorService : BackgroundService
                      && claimedLocalEndpoint is not null
                      && token is not null)
             {
-                _ = processor.ProcessRequest(claimedLocalEndpoint, endPoint, token, sink);
+                _ = processor.ProcessRequestAfterIngress(
+                    claimedLocalEndpoint, endPoint, token, sink);
             }
 
             // Every inbound packet is consumed here. NatPunchModule is used only for outbound introductions.

src/FinalFactory.Rendezvous.Server/appsettings.Development.json

@@ -1,5 +1,8 @@
 {
   "Rendezvous": {
+    "AbuseProtection": {
+      "OperatorAllowedAddresses": ["127.0.0.1", "::1"]
+    },
     "Provisioning": {
       "Issuer": "final-factory-rendezvous-development",
       "Audience": "final-factory-rendezvous",
@@ -14,6 +17,14 @@
           "NotBefore": "2025-01-01T00:00:00Z",
           "SignUntil": "2035-01-01T00:00:00Z",
           "VerifyUntil": "2035-01-02T00:00:00Z"
+        },
+        {
+          "KeyId": "development-operator-1",
+          "SecretReference": "development:ephemeral/rendezvous-operator-signing",
+          "CredentialKinds": ["Operator"],
+          "NotBefore": "2025-01-01T00:00:00Z",
+          "SignUntil": "2035-01-01T00:00:00Z",
+          "VerifyUntil": "2035-01-02T00:00:00Z"
         }
       ],
       "Games": [

src/FinalFactory.Rendezvous.Server/appsettings.json

@@ -1,10 +1,60 @@
 {
   "Rendezvous": {
+    "Deployment": {
+      "PublicHttpBaseUrl": "",
+      "PublicUdpHost": "",
+      "PublicUdpPort": 9050,
+      "DrainDeadlineSeconds": 30,
+      "MinimumDrainSeconds": 1,
+      "SingleActiveInstance": true,
+      "AllowPrivatePublicEndpoints": false
+    },
     "Udp": {
       "ListenAddress": "0.0.0.0",
       "Port": 9050,
       "MaxDatagramsPerPoll": 256,
       "PollIntervalMilliseconds": 2
+    },
+    "Audit": {
+      "MaxEntries": 10000,
+      "RetentionDays": 30
+    },
+    "AbuseProtection": {
+      "WindowSeconds": 1,
+      "MaxTrackedKeys": 100000,
+      "CriticalTrackedKeyReserve": 2048,
+      "UdpTrackedKeyLimit": 70000,
+      "TrustedProxyAddresses": [],
+      "OperatorAllowedAddresses": [],
+      "HealthGlobalRequestsPerWindow": 1000,
+      "HealthGlobalConcurrency": 32,
+      "HealthIpPrefixRequestsPerWindow": 120,
+      "HealthIpPrefixConcurrency": 8,
+      "OperatorGlobalRequestsPerWindow": 1000,
+      "OperatorGlobalConcurrency": 32,
+      "OperatorIpPrefixRequestsPerWindow": 120,
+      "OperatorIpPrefixConcurrency": 8,
+      "HttpGlobalRequestsPerWindow": 20000,
+      "HttpOptionalRequestsPerWindow": 18000,
+      "HttpIpPrefixRequestsPerWindow": 500,
+      "HttpOptionalIpPrefixRequestsPerWindow": 450,
+      "HttpOperationRequestsPerWindow": 5000,
+      "HttpTenantRequestsPerWindow": 2000,
+      "HttpPrincipalRequestsPerWindow": 500,
+      "HttpResourceRequestsPerWindow": 200,
+      "HttpGlobalConcurrency": 1024,
+      "HttpOptionalConcurrency": 768,
+      "HttpIpPrefixConcurrency": 64,
+      "HttpOptionalIpPrefixConcurrency": 48,
+      "HttpOperationConcurrency": 256,
+      "HttpTenantConcurrency": 256,
+      "HttpPrincipalConcurrency": 32,
+      "HttpResourceConcurrency": 16,
+      "UdpGlobalDatagramsPerWindow": 100000,
+      "UdpIpPrefixDatagramsPerWindow": 2000,
+      "UdpOperationDatagramsPerWindow": 50000,
+      "UdpCapabilityDatagramsPerWindow": 120,
+      "UdpResourceDatagramsPerWindow": 240
     }
   },
   "Logging": {

src/FinalFactory.Rendezvous.TestClient/DirectEchoProtocol.cs

@@ -0,0 +1,130 @@
+using System.Security.Cryptography;
+using System.Text;
+using LiteNetLib;
+using LiteNetLib.Utils;
+
+namespace FinalFactory.Rendezvous.TestClient;
+
+internal sealed class DirectEchoProtocol : IDisposable
+{
+    private const string PingPrefix = "rv1-ping:";
+    private const string EchoPrefix = "rv1-echo:";
+    private const string AckPrefix = "rv1-ack:";
+    private const string DonePrefix = "rv1-done:";
+    private readonly EventBasedNetListener _events;
+    private readonly bool _host;
+    private readonly Dictionary<NetPeer, string> _hostNonces = [];
+    private readonly TaskCompletionSource<bool> _completed = new(
+        TaskCreationOptions.RunContinuationsAsynchronously);
+    private string? _nonce;
+    private bool _disposed;
+
+    internal DirectEchoProtocol(EventBasedNetListener events, bool host)
+    {
+        _events = events ?? throw new ArgumentNullException(nameof(events));
+        _host = host;
+        _events.NetworkReceiveEvent += OnReceive;
+        _events.PeerDisconnectedEvent += OnPeerDisconnected;
+    }
+
+    internal Task Completion => _completed.Task;
+    internal int PendingHostExchangeCount => _hostNonces.Count;
+    internal event Action<NetPeer>? ExchangeCompleted;
+
+    internal void BeginJoin(NetPeer peer)
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        if (_host || _nonce is not null)
+        {
+            throw new InvalidOperationException("The direct echo exchange is already active.");
+        }
+
+        _nonce = Convert.ToHexString(RandomNumberGenerator.GetBytes(16)).ToLowerInvariant();
+        Send(peer, PingPrefix + _nonce);
+    }
+
+    public void Dispose()
+    {
+        if (_disposed)
+        {
+            return;
+        }
+        _events.NetworkReceiveEvent -= OnReceive;
+        _events.PeerDisconnectedEvent -= OnPeerDisconnected;
+        _hostNonces.Clear();
+        _disposed = true;
+    }
+
+    private void OnReceive(
+        NetPeer peer,
+        NetPacketReader reader,
+        byte channel,
+        DeliveryMethod deliveryMethod)
+    {
+        try
+        {
+            ReadOnlySpan<byte> payload = reader.GetRemainingBytesSpan();
+            if (payload.Length is < 9 or > 64)
+            {
+                return;
+            }
+            string message = Encoding.ASCII.GetString(payload);
+            if (_host && TryNonce(message, PingPrefix, out string? pingNonce))
+            {
+                _hostNonces[peer] = pingNonce!;
+                Send(peer, EchoPrefix + pingNonce);
+            }
+            else if (_host
+                     && _hostNonces.TryGetValue(peer, out string? hostNonce)
+                     && string.Equals(message, AckPrefix + hostNonce, StringComparison.Ordinal))
+            {
+                _hostNonces.Remove(peer);
+                Send(peer, DonePrefix + hostNonce);
+                ExchangeCompleted?.Invoke(peer);
+                _completed.TrySetResult(true);
+            }
+            else if (!_host
+                     && _nonce is not null
+                     && string.Equals(message, EchoPrefix + _nonce, StringComparison.Ordinal))
+            {
+                Send(peer, AckPrefix + _nonce);
+            }
+            else if (!_host
+                     && _nonce is not null
+                     && string.Equals(message, DonePrefix + _nonce, StringComparison.Ordinal))
+            {
+                ExchangeCompleted?.Invoke(peer);
+                _completed.TrySetResult(true);
+            }
+        }
+        finally
+        {
+            reader.Recycle();
+        }
+    }
+
+    private static bool TryNonce(string message, string prefix, out string? nonce)
+    {
+        nonce = null;
+        if (!message.StartsWith(prefix, StringComparison.Ordinal)
+            || message.Length != prefix.Length + 32)
+        {
+            return false;
+        }
+        string candidate = message[prefix.Length..];
+        if (!candidate.All(static character => character is >= '0' and <= '9'
+                or >= 'a' and <= 'f'))
+        {
+            return false;
+        }
+        nonce = candidate;
+        return true;
+    }
+
+    private static void Send(NetPeer peer, string message) => peer.Send(
+        Encoding.ASCII.GetBytes(message),
+        DeliveryMethod.ReliableOrdered);
+
+    private void OnPeerDisconnected(NetPeer peer, DisconnectInfo disconnectInfo) =>
+        _hostNonces.Remove(peer);
+}

src/FinalFactory.Rendezvous.TestClient/HostServiceFailureBudget.cs

@@ -0,0 +1,36 @@
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.TestClient;
+
+internal sealed class HostServiceFailureBudget
+{
+    private const int MaximumConsecutiveTransientFailures = 3;
+    private int _consecutiveTransientFailures;
+
+    internal bool ShouldStop(
+        RendezvousErrorCode error,
+        DateTimeOffset leaseExpiresAt,
+        DateTimeOffset now)
+    {
+        if (error == RendezvousErrorCode.None)
+        {
+            Reset();
+            return false;
+        }
+        if (!IsTransient(error))
+        {
+            return true;
+        }
+
+        _consecutiveTransientFailures++;
+        return _consecutiveTransientFailures >= MaximumConsecutiveTransientFailures
+            || now >= leaseExpiresAt;
+    }
+
+    internal void Reset() => _consecutiveTransientFailures = 0;
+
+    private static bool IsTransient(RendezvousErrorCode error) => error is
+        RendezvousErrorCode.RateLimited
+        or RendezvousErrorCode.ServiceUnavailable
+        or RendezvousErrorCode.InternalError;
+}

src/FinalFactory.Rendezvous.TestClient/Program.cs

@@ -1,16 +1,29 @@
 namespace FinalFactory.Rendezvous.TestClient;
 
-/// <summary>
-/// Bootstrap entry point for the public-SDK-only diagnostic client.
-/// </summary>
 public static class Program
 {
-    /// <summary>
-    /// Runs the bootstrap diagnostic.
-    /// </summary>
-    public static int Main()
+    public static async Task<int> Main(string[] args)
     {
-        Console.WriteLine("Rendezvous TestClient bootstrap is ready.");
-        return 0;
+        using CancellationTokenSource shutdown = new();
+        ConsoleCancelEventHandler cancelHandler = (_, eventArgs) =>
+        {
+            eventArgs.Cancel = true;
+            shutdown.Cancel();
+        };
+        Console.CancelKeyPress += cancelHandler;
+        try
+        {
+            TestClientApplication application = new(new RendezvousCommandRunner());
+            return await application.RunAsync(
+                args,
+                Console.In,
+                Console.Out,
+                Console.Error,
+                shutdown.Token).ConfigureAwait(false);
+        }
+        finally
+        {
+            Console.CancelKeyPress -= cancelHandler;
+        }
     }
 }

src/FinalFactory.Rendezvous.TestClient/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("FinalFactory.Rendezvous.Tests")]

src/FinalFactory.Rendezvous.TestClient/README.md

@@ -0,0 +1,56 @@
+# FinalFactory.Rendezvous.TestClient
+
+This is a diagnostic executable for exercising Rendezvous through the same public
+Client and Contracts API available to a game. It is not a production game client,
+server browser, dedicated server, relay, account system, or gameplay host.
+
+The executable has three explicit modes:
+
+- `host` publishes a session, maintains presence and its lease, accepts an
+authenticated direct peer, and answers a bounded ping/echo/ack/completion exchange;
+- `browse` prints compatible public listings; and
+- `join` selects or accepts a listing, drives traversal on its caller-owned
+  LiteNetLib socket, proves direct traffic, reports the typed outcome, and exits.
+
+Run `dotnet run --project src/FinalFactory.Rendezvous.TestClient -- --help` for
+the complete option reference. A typical script-mode invocation is:
+
+```bash
+export RENDEZVOUS_PUBLISHER_CREDENTIAL='<credential from the deployment boundary>'
+dotnet run --project src/FinalFactory.Rendezvous.TestClient -- \
+  host --service http://127.0.0.1:5000/ --mediator 127.0.0.1:9050 \
+  --game space-game --environment development --region local --protocol 1 \
+  --script --json --exit-after-echo
+```
+
+Publisher credentials are accepted only through a named environment variable.
+There is deliberately no command-line credential option because process command
+lines are routinely exposed to other local tools and diagnostics. Output uses an
+allowlisted event model and never includes lease tokens, punch capabilities,
+connection tickets, raw metadata, signing material, or reusable credentials.
+
+Script mode never prompts. Join mode selects the first compatible listing unless
+`--listing UUID` fixes the choice. `--json` emits one JSON object per line with
+`version: 1`; event names and the process exit codes below are stable automation
+contracts. A script-mode host without `--run-seconds` uses `--timeout-seconds` as
+its total runtime bound. New optional event properties may be added without changing
+the version. JSON help and usage failures are versioned events as well; informational
+events use stdout and failures use stderr.
+
+| Exit | Meaning |
+|---:|---|
+| `0` | Requested diagnostic flow completed successfully |
+| `2` | Invalid command or options |
+| `3` | Missing or invalid local configuration |
+| `10` | HTTP, registration, browser, lease, or socket failure |
+| `11` | No compatible session was available or selected |
+| `12` | Authorization or traversal reached a typed terminal failure |
+| `13` | A requested direct ping/echo proof did not complete |
+| `130` | Caller cancellation or Ctrl+C |
+
+The client prints the selected direct endpoint category (`loopback`, `private`, or
+`public`) but never the raw endpoint. A traversal failure reports whether an
+authoritative dedicated fallback is available; the diagnostic does not connect to
+that fallback automatically. A host may publish a policy-authorized endpoint with
+`--fallback IP:PORT`. See the repository integration guide for process
+orchestration and topology limitations.

src/FinalFactory.Rendezvous.TestClient/RendezvousCommandRunner.cs

@@ -0,0 +1,774 @@
+using System.Diagnostics;
+using System.Net;
+using System.Net.Sockets;
+using FinalFactory.Rendezvous.Client;
+using FinalFactory.Rendezvous.Contracts;
+using LiteNetLib;
+
+namespace FinalFactory.Rendezvous.TestClient;
+
+internal sealed class RendezvousCommandRunner : ITestClientCommandRunner
+{
+    private static readonly TimeSpan PollDelay = TimeSpan.FromMilliseconds(5);
+    private static readonly TimeSpan HostRefreshInterval = TimeSpan.FromMilliseconds(250);
+    private static readonly TimeSpan DirectTrafficFlushGrace = TimeSpan.FromMilliseconds(500);
+
+    public Task<TestClientExitCode> RunAsync(
+        TestClientOptions options,
+        TestClientOutput output,
+        TextReader input,
+        CancellationToken cancellationToken) => options.Mode switch
+        {
+            TestClientMode.Host => RunHostAsync(options, output, cancellationToken),
+            TestClientMode.Browse => RunBrowseAsync(options, output, cancellationToken),
+            TestClientMode.Join => RunJoinAsync(options, output, input, cancellationToken),
+            _ => Task.FromResult(TestClientExitCode.Usage),
+        };
+
+    private static async Task<TestClientExitCode> RunHostAsync(
+        TestClientOptions options,
+        TestClientOutput output,
+        CancellationToken cancellationToken)
+    {
+        string? publisherCredential = Environment.GetEnvironmentVariable(
+            options.PublisherCredentialEnvironmentVariable);
+        if (!ContractValidation.IsOpaqueHttpCredentialValid(publisherCredential))
+        {
+            output.WriteError(
+                "host.configuration",
+                "failed",
+                "The publisher credential environment variable is missing or invalid.",
+                phase: "configuration");
+            return TestClientExitCode.Configuration;
+        }
+        string credential = publisherCredential!;
+
+        using HttpClient http = CreateHttpClient(options);
+        RendezvousPublisherClient publisher = new(http, ClientOptions(options));
+        RendezvousSessionBrowserClient browser = new(http, ClientOptions(options));
+        RendezvousJoinClient joins = new(http, ClientOptions(options));
+        RendezvousNetListener events = new();
+        NetManager manager = events.CreateManager();
+        if (!manager.Start(options.LocalPort))
+        {
+            output.WriteError("host.socket", "failed", "The gameplay UDP socket could not start.", phase: "presence");
+            return TestClientExitCode.ServiceFailure;
+        }
+
+        PublishedSession? session = null;
+        using CancellationTokenSource hostOperations = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+        Task<RendezvousClientResult<int>>? refresh = null;
+        Task<RendezvousClientResult<RenewLeaseResponse>>? renewal = null;
+        Task<RendezvousClientResult<GetSessionResponse>>? readiness = null;
+        DirectEchoProtocol? echo = null;
+        RendezvousHostCoordinator? coordinator = null;
+        TestClientExitCode hostResult = TestClientExitCode.ServiceFailure;
+        bool cleanupFailed = false;
+        try
+        {
+            output.Write("host.registration", "started", phase: "registration");
+            RendezvousClientResult<PublishedSession> registration;
+            using (CancellationTokenSource registrationTimeout = CreateOperationTimeout(options, cancellationToken))
+            {
+                try
+                {
+                    registration = await publisher.RegisterAsync(
+                        new RegisterSessionRequest
+                        {
+                            IdempotencyKey = Guid.NewGuid().ToString("N"),
+                            GameId = options.GameId,
+                            EnvironmentId = options.EnvironmentId,
+                            RegionId = options.RegionId,
+                            ProtocolVersion = options.ProtocolVersion,
+                            BuildVersion = options.BuildVersion,
+                            DisplayName = options.DisplayName,
+                            Visibility = ListingVisibility.Public,
+                            Capacity = new SessionCapacity { CurrentPlayers = 1, MaximumPlayers = 8 },
+                            Metadata = new Dictionary<string, string>(options.Metadata, StringComparer.Ordinal),
+                            DedicatedFallback = options.DedicatedFallback,
+                        },
+                        credential,
+                        registrationTimeout.Token).ConfigureAwait(false);
+                }
+                catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
+                {
+                    output.WriteError(
+                        "host.registration",
+                        "timed-out",
+                        "Host registration exceeded the bounded startup stage.",
+                        phase: "registration");
+                    return TestClientExitCode.ServiceFailure;
+                }
+            }
+            if (!registration.IsSuccess || registration.Value is null)
+            {
+                WriteServiceFailure(output, "host.registration", "registration", registration);
+                return TestClientExitCode.ServiceFailure;
+            }
+
+            session = registration.Value;
+            output.Write(
+                "host.registered",
+                "registered",
+                phase: "registration",
+                listingId: session.ListingId.ToString(),
+                displayName: options.DisplayName);
+            echo = new DirectEchoProtocol(events.GameplayEvents, host: true);
+            echo.ExchangeCompleted += _ => output.Write(
+                "host.direct-traffic",
+                "verified",
+                phase: "direct-traffic",
+                endpointType: "peer-to-peer");
+            coordinator = new RendezvousHostCoordinator(
+                manager,
+                events,
+                options.Mediator,
+                session,
+                joins,
+                CoordinatorOptions(options));
+            coordinator.AttemptCompleted += (_, completion) =>
+            {
+                output.Write(
+                    "host.attempt.completed",
+                    completion.Outcome.IsSuccess ? "connected" : "failed",
+                    phase: completion.Outcome.Phase.ToString(),
+                    outcome: completion.Outcome.Kind.ToString(),
+                    elapsedMilliseconds: ToMilliseconds(completion.Outcome.Elapsed));
+                if (completion.Outcome.IsSuccess)
+                {
+                    output.Write(
+                        "host.direct-connect",
+                        "connected",
+                        phase: "direct-connection",
+                        endpointType: "peer-to-peer");
+                }
+            };
+
+            Stopwatch running = Stopwatch.StartNew();
+            TimeSpan nextRefresh = TimeSpan.Zero;
+            TimeSpan nextRenewal = TimeSpan.FromSeconds(session.LeaseRenewAfterSeconds);
+            TimeSpan nextReadinessProbe = TimeSpan.Zero;
+            bool directTrafficReported = false;
+            TimeSpan? directTrafficCompletedAt = null;
+            bool ready = false;
+            bool terminalFailure = false;
+            int previousPendingAttempts = 0;
+            HostServiceFailureBudget refreshFailures = new();
+            HostServiceFailureBudget renewalFailures = new();
+            using PeriodicTimer pollTimer = new(PollDelay);
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                coordinator.Poll();
+                if (coordinator.State != RendezvousHostState.Active)
+                {
+                    output.WriteError(
+                        "host.lifecycle",
+                        "failed",
+                        "The host coordinator stopped before shutdown was requested.",
+                        phase: "lifecycle",
+                        outcome: coordinator.State.ToString());
+                    terminalFailure = true;
+                    break;
+                }
+                if (coordinator.PendingAttemptCount > previousPendingAttempts)
+                {
+                    output.Write(
+                        "host.punch",
+                        "started",
+                        phase: "nat-traversal",
+                        count: coordinator.PendingAttemptCount);
+                }
+                previousPendingAttempts = coordinator.PendingAttemptCount;
+                if (readiness is { IsCompleted: true })
+                {
+                    RendezvousClientResult<GetSessionResponse> result = await readiness.ConfigureAwait(false);
+                    readiness = null;
+                    if (result.IsSuccess)
+                    {
+                        ready = true;
+                        output.Write(
+                            "host.ready",
+                            "ready",
+                            phase: "presence",
+                            listingId: session.ListingId.ToString());
+                    }
+                    else
+                    {
+                        nextReadinessProbe = running.Elapsed + TimeSpan.FromMilliseconds(50);
+                    }
+                }
+                if (!ready && readiness is null && running.Elapsed >= nextReadinessProbe)
+                {
+                    readiness = browser.GetAsync(
+                        session.ListingId,
+                        options.GameId,
+                        options.EnvironmentId,
+                        options.ProtocolVersion,
+                        hostOperations.Token);
+                }
+                if (refresh is { IsCompleted: true })
+                {
+                    RendezvousClientResult<int> result = await refresh.ConfigureAwait(false);
+                    refresh = null;
+                    nextRefresh = running.Elapsed + (result.IsSuccess
+                        ? HostRefreshInterval
+                        : TimeSpan.FromSeconds(1));
+                    if (!result.IsSuccess)
+                    {
+                        WriteServiceFailure(output, "host.authorization", "authorization", result);
+                        if (refreshFailures.ShouldStop(result.Error, session.ExpiresAt, DateTimeOffset.UtcNow))
+                        {
+                            terminalFailure = true;
+                            break;
+                        }
+                    }
+                    else
+                    {
+                        refreshFailures.Reset();
+                    }
+                }
+                if (refresh is null && running.Elapsed >= nextRefresh)
+                {
+                    refresh = coordinator.RefreshJoinAttemptsAsync(hostOperations.Token);
+                }
+
+                if (renewal is { IsCompleted: true })
+                {
+                    RendezvousClientResult<RenewLeaseResponse> result = await renewal.ConfigureAwait(false);
+                    renewal = null;
+                    nextRenewal = running.Elapsed + (result.IsSuccess && result.Value is not null
+                        ? TimeSpan.FromSeconds(result.Value.RenewAfterSeconds)
+                        : TimeSpan.FromSeconds(1));
+                    output.Write(
+                        "host.lease",
+                        result.IsSuccess ? "renewed" : "failed",
+                        phase: "lease",
+                        message: result.IsSuccess ? null : SafeServiceMessage(result));
+                    if (!result.IsSuccess
+                        && renewalFailures.ShouldStop(result.Error, session.ExpiresAt, DateTimeOffset.UtcNow))
+                    {
+                        terminalFailure = true;
+                        break;
+                    }
+                    if (result.IsSuccess)
+                    {
+                        renewalFailures.Reset();
+                    }
+                }
+                if (renewal is null && running.Elapsed >= nextRenewal)
+                {
+                    renewal = publisher.RenewAsync(session, credential, hostOperations.Token);
+                }
+
+                if (echo.Completion.IsCompleted && !directTrafficReported)
+                {
+                    directTrafficReported = true;
+                    directTrafficCompletedAt = running.Elapsed;
+                }
+                if (options.ExitAfterEcho
+                    && directTrafficCompletedAt.HasValue
+                    && running.Elapsed - directTrafficCompletedAt.Value >= DirectTrafficFlushGrace)
+                {
+                    break;
+                }
+                if (options.RunDuration.HasValue && running.Elapsed >= options.RunDuration.Value)
+                {
+                    break;
+                }
+                if (!await pollTimer.WaitForNextTickAsync(cancellationToken).ConfigureAwait(false))
+                {
+                    break;
+                }
+            }
+
+            if (cancellationToken.IsCancellationRequested)
+            {
+                hostResult = TestClientExitCode.Cancelled;
+            }
+            else if (terminalFailure)
+            {
+                hostResult = TestClientExitCode.ServiceFailure;
+            }
+            else if (options.ExitAfterEcho && !directTrafficReported)
+            {
+                output.WriteError(
+                    "host.direct-traffic",
+                    "timed-out",
+                    "No authenticated ping/echo/ack exchange completed within the host runtime.",
+                    phase: "direct-traffic");
+                hostResult = TestClientExitCode.DirectTrafficFailed;
+            }
+            else
+            {
+                hostResult = TestClientExitCode.Success;
+            }
+        }
+        finally
+        {
+            hostOperations.Cancel();
+            await ObserveCancellationAsync(refresh).ConfigureAwait(false);
+            await ObserveCancellationAsync(renewal).ConfigureAwait(false);
+            await ObserveCancellationAsync(readiness).ConfigureAwait(false);
+            coordinator?.Dispose();
+            echo?.Dispose();
+            if (session is not null)
+            {
+                using CancellationTokenSource cleanup = new(TimeSpan.FromSeconds(5));
+                try
+                {
+                    RendezvousClientResult<bool> deregistered = await publisher.DeregisterAsync(
+                        session,
+                        credential,
+                        cleanup.Token).ConfigureAwait(false);
+                    output.Write(
+                        "host.deregistered",
+                        deregistered.IsSuccess ? "complete" : "failed",
+                        phase: "lifecycle",
+                        listingId: session.ListingId.ToString());
+                    if (!deregistered.IsSuccess)
+                    {
+                        cleanupFailed = true;
+                    }
+                }
+                catch (OperationCanceledException)
+                {
+                    output.WriteError(
+                        "host.deregistered",
+                        "timed-out",
+                        "Deregistration did not complete within the cleanup budget.",
+                        phase: "lifecycle");
+                    cleanupFailed = true;
+                }
+            }
+            manager.Stop();
+        }
+        return cleanupFailed && !cancellationToken.IsCancellationRequested
+            ? TestClientExitCode.ServiceFailure
+            : hostResult;
+    }
+
+    private static async Task<TestClientExitCode> RunBrowseAsync(
+        TestClientOptions options,
+        TestClientOutput output,
+        CancellationToken cancellationToken)
+    {
+        using CancellationTokenSource operation = CreateOperationTimeout(options, cancellationToken);
+        using HttpClient http = CreateHttpClient(options);
+        RendezvousSessionBrowserClient browser = new(http, ClientOptions(options));
+        output.Write("browse.sessions", "started", phase: "directory");
+        RendezvousClientResult<IReadOnlyList<SessionListing>> result = await browser.BrowseAllAsync(
+            BrowseRequest(options),
+            maximumPages: 10,
+            cancellationToken: operation.Token).ConfigureAwait(false);
+        if (!result.IsSuccess || result.Value is null)
+        {
+            WriteServiceFailure(output, "browse.sessions", "directory", result);
+            return TestClientExitCode.ServiceFailure;
+        }
+
+        WriteListings(output, result.Value);
+        return result.Value.Count == 0
+            ? TestClientExitCode.NoCompatibleSession
+            : TestClientExitCode.Success;
+    }
+
+    private static async Task<TestClientExitCode> RunJoinAsync(
+        TestClientOptions options,
+        TestClientOutput output,
+        TextReader input,
+        CancellationToken cancellationToken)
+    {
+        using CancellationTokenSource operation = CreateOperationTimeout(options, cancellationToken);
+        using HttpClient http = CreateHttpClient(options);
+        RendezvousSessionBrowserClient browser = new(http, ClientOptions(options));
+        RendezvousJoinClient joins = new(http, ClientOptions(options));
+        SessionSelection selection = await SelectListingAsync(
+            options,
+            output,
+            input,
+            browser,
+            operation.Token).ConfigureAwait(false);
+        if (selection.Listing is null)
+        {
+            return selection.ExitCode;
+        }
+        SessionListing listing = selection.Listing;
+
+        RendezvousNetListener events = new();
+        NetManager manager = events.CreateManager();
+        if (!manager.Start(options.LocalPort))
+        {
+            output.WriteError("join.socket", "failed", "The gameplay UDP socket could not start.", phase: "mediation");
+            return TestClientExitCode.ServiceFailure;
+        }
+
+        RendezvousClientCoordinator? coordinator = null;
+        bool directConnected = false;
+        try
+        {
+            output.Write(
+                "join.authorization",
+                "started",
+                phase: "authorization",
+                listingId: listing.ListingId.ToString());
+            RendezvousConnectionStartResult start = await joins.CreateConnectionAttemptAsync(
+                new CreateJoinAttemptRequest
+                {
+                    IdempotencyKey = Guid.NewGuid().ToString("N"),
+                    GameId = options.GameId,
+                    EnvironmentId = options.EnvironmentId,
+                    ListingId = listing.ListingId,
+                    ProtocolVersion = options.ProtocolVersion,
+                },
+                listing.DedicatedFallback,
+                operation.Token).ConfigureAwait(false);
+            if (start.Outcome is { } serviceOutcome)
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+                WriteOutcome(output, "join.authorization", serviceOutcome);
+                WriteFallback(output, serviceOutcome);
+                return TestClientExitCode.TraversalFailed;
+            }
+
+            CreateJoinAttemptResponse attempt = start.Attempt
+                ?? throw new InvalidOperationException("The typed start result had no attempt or outcome.");
+            using DirectEchoProtocol echo = new(events.GameplayEvents, host: false);
+            coordinator = new RendezvousClientCoordinator(
+                manager,
+                events,
+                options.Mediator,
+                attempt,
+                CoordinatorOptions(options));
+            output.Write("join.punch", "started", phase: "nat-traversal");
+            using (CancellationTokenSource traversal = CreateOperationTimeout(options, cancellationToken))
+            using (PeriodicTimer traversalPoll = new(PollDelay))
+            {
+                RendezvousConnectionState previousState = coordinator.State;
+                while (!coordinator.IsCompleted)
+                {
+                    traversal.Token.ThrowIfCancellationRequested();
+                    coordinator.Poll();
+                    if (coordinator.State != previousState)
+                    {
+                        previousState = coordinator.State;
+                        if (previousState == RendezvousConnectionState.Connecting)
+                        {
+                            output.Write(
+                                "join.direct-connect",
+                                "started",
+                                phase: "direct-connection");
+                        }
+                    }
+                    if (!coordinator.IsCompleted
+                        && !await traversalPoll.WaitForNextTickAsync(traversal.Token).ConfigureAwait(false))
+                    {
+                        break;
+                    }
+                }
+            }
+
+            RendezvousConnectionOutcome outcome = coordinator.Outcome
+                ?? throw new InvalidOperationException("The completed coordinator had no typed outcome.");
+            WriteOutcome(output, "join.traversal", outcome);
+            if (!outcome.IsSuccess || coordinator.ConnectedPeer is null)
+            {
+                WriteFallback(output, outcome);
+                await ReportOutcomeAsync(coordinator, joins, output, cancellationToken).ConfigureAwait(false);
+                return TestClientExitCode.TraversalFailed;
+            }
+
+            NetPeer peer = coordinator.ConnectedPeer;
+            directConnected = true;
+            string endpointType = EndpointType(peer.Address);
+            output.Write(
+                "join.connected",
+                "connected",
+                phase: "direct-connection",
+                endpointType: endpointType,
+                elapsedMilliseconds: ToMilliseconds(outcome.Elapsed));
+            await ReportOutcomeAsync(coordinator, joins, output, cancellationToken).ConfigureAwait(false);
+            echo.BeginJoin(peer);
+            using (CancellationTokenSource traffic = CreateOperationTimeout(options, cancellationToken))
+            using (PeriodicTimer trafficPoll = new(PollDelay))
+            {
+                while (!echo.Completion.IsCompleted)
+                {
+                    traffic.Token.ThrowIfCancellationRequested();
+                    manager.PollEvents();
+                    if (!echo.Completion.IsCompleted
+                        && !await trafficPoll.WaitForNextTickAsync(traffic.Token).ConfigureAwait(false))
+                    {
+                        break;
+                    }
+                }
+            }
+            await echo.Completion.ConfigureAwait(false);
+            output.Write(
+                "join.direct-traffic",
+                "verified",
+                phase: "direct-traffic",
+                endpointType: endpointType);
+            peer.Disconnect();
+            manager.PollEvents();
+            return TestClientExitCode.Success;
+        }
+        catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
+        {
+            output.WriteError(
+                "join.timeout",
+                "timed-out",
+                "The bounded join operation timed out.",
+                phase: "lifecycle",
+                outcome: ConnectionOutcomeKind.TimedOut.ToString());
+            if (coordinator is not null && !coordinator.IsCompleted)
+            {
+                coordinator.Poll();
+            }
+            if (coordinator is not null && !coordinator.IsCompleted)
+            {
+                coordinator.Cancel();
+                coordinator.Poll();
+                if (coordinator.Outcome is { } timeoutOutcome)
+                {
+                    WriteOutcome(output, "join.traversal", timeoutOutcome);
+                    WriteFallback(output, timeoutOutcome, listing.DedicatedFallback);
+                    await ReportOutcomeAsync(
+                        coordinator,
+                        joins,
+                        output,
+                        cancellationToken).ConfigureAwait(false);
+                }
+            }
+            return directConnected
+                ? TestClientExitCode.DirectTrafficFailed
+                : TestClientExitCode.TraversalFailed;
+        }
+        finally
+        {
+            coordinator?.Dispose();
+            manager.Stop();
+        }
+    }
+
+    private static async Task<SessionSelection> SelectListingAsync(
+        TestClientOptions options,
+        TestClientOutput output,
+        TextReader input,
+        RendezvousSessionBrowserClient browser,
+        CancellationToken cancellationToken)
+    {
+        if (options.ListingId.HasValue)
+        {
+            RendezvousClientResult<GetSessionResponse> exact = await browser.GetAsync(
+                options.ListingId.Value,
+                options.GameId,
+                options.EnvironmentId,
+                options.ProtocolVersion,
+                cancellationToken).ConfigureAwait(false);
+            if (!exact.IsSuccess || exact.Value is null)
+            {
+                WriteServiceFailure(output, "join.selection", "directory", exact);
+                return new(null, TestClientExitCode.ServiceFailure);
+            }
+            return new(exact.Value.Session, TestClientExitCode.Success);
+        }
+
+        RendezvousClientResult<IReadOnlyList<SessionListing>> result = await browser.BrowseAllAsync(
+            BrowseRequest(options),
+            maximumPages: 10,
+            cancellationToken: cancellationToken).ConfigureAwait(false);
+        if (!result.IsSuccess || result.Value is null)
+        {
+            WriteServiceFailure(output, "join.selection", "directory", result);
+            return new(null, TestClientExitCode.ServiceFailure);
+        }
+        if (result.Value.Count == 0)
+        {
+            output.Write("join.selection", "empty", phase: "directory", count: 0);
+            return new(null, TestClientExitCode.NoCompatibleSession);
+        }
+        WriteListings(output, result.Value);
+        if (options.Script)
+        {
+            return new(result.Value[0], TestClientExitCode.Success);
+        }
+
+        output.WritePrompt($"Select session [1-{result.Value.Count}]: ");
+        string? selection = await input.ReadLineAsync(cancellationToken).ConfigureAwait(false);
+        SessionListing? selected = int.TryParse(selection, out int index)
+            && index >= 1
+            && index <= result.Value.Count
+                ? result.Value[index - 1]
+                : null;
+        return selected is null
+            ? new(null, TestClientExitCode.NoCompatibleSession)
+            : new(selected, TestClientExitCode.Success);
+    }
+
+    private static void WriteListings(TestClientOutput output, IReadOnlyList<SessionListing> listings)
+    {
+        output.Write("browse.completed", "complete", phase: "directory", count: listings.Count);
+        foreach (SessionListing listing in listings)
+        {
+            output.Write(
+                "browse.session",
+                "available",
+                phase: "directory",
+                listingId: listing.ListingId.ToString(),
+                displayName: listing.DisplayName);
+        }
+    }
+
+    private static BrowseSessionsRequest BrowseRequest(TestClientOptions options) => new()
+    {
+        GameId = options.GameId,
+        EnvironmentId = options.EnvironmentId,
+        ProtocolVersion = options.ProtocolVersion,
+        RegionId = options.RegionId,
+        PageSize = options.PageSize,
+        ExcludeFull = true,
+    };
+
+    private static HttpClient CreateHttpClient(TestClientOptions options) => new()
+    {
+        BaseAddress = options.ServiceUri,
+        Timeout = Timeout.InfiniteTimeSpan,
+    };
+
+    private static RendezvousClientOptions ClientOptions(TestClientOptions options) => new()
+    {
+        RequestTimeout = TimeSpan.FromSeconds(Math.Min(30, options.OperationTimeout.TotalSeconds)),
+    };
+
+    private static RendezvousCoordinatorOptions CoordinatorOptions(TestClientOptions options)
+    {
+        TimeSpan phaseTimeout = TimeSpan.FromSeconds(
+            Math.Min(30, options.OperationTimeout.TotalSeconds * 0.45));
+        return new RendezvousCoordinatorOptions
+        {
+            PunchTimeout = phaseTimeout,
+            DirectConnectTimeout = phaseTimeout,
+        };
+    }
+
+    private static CancellationTokenSource CreateOperationTimeout(
+        TestClientOptions options,
+        CancellationToken cancellationToken)
+    {
+        CancellationTokenSource source = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+        source.CancelAfter(options.OperationTimeout);
+        return source;
+    }
+
+    private static async Task ReportOutcomeAsync(
+        RendezvousClientCoordinator coordinator,
+        RendezvousJoinClient joins,
+        TestClientOutput output,
+        CancellationToken callerCancellationToken)
+    {
+        using CancellationTokenSource telemetry = CancellationTokenSource.CreateLinkedTokenSource(
+            callerCancellationToken);
+        telemetry.CancelAfter(TimeSpan.FromSeconds(5));
+        try
+        {
+            RendezvousClientResult<ReportConnectionOutcomeResponse> report =
+                await coordinator.ReportOutcomeAsync(joins, telemetry.Token).ConfigureAwait(false);
+            output.Write(
+                "join.outcome-report",
+                report.IsSuccess ? "accepted" : "failed",
+                phase: "telemetry",
+                message: report.IsSuccess ? null : SafeServiceMessage(report));
+        }
+        catch (OperationCanceledException) when (!callerCancellationToken.IsCancellationRequested)
+        {
+            output.WriteError(
+                "join.outcome-report",
+                "cancelled",
+                "Outcome reporting was cancelled within the operation budget.",
+                phase: "telemetry");
+        }
+    }
+
+    private static void WriteOutcome(
+        TestClientOutput output,
+        string eventName,
+        RendezvousConnectionOutcome outcome) => output.Write(
+            eventName,
+            outcome.IsSuccess ? "connected" : "failed",
+            phase: outcome.Phase.ToString(),
+            outcome: outcome.Kind.ToString(),
+            elapsedMilliseconds: ToMilliseconds(outcome.Elapsed));
+
+    private static void WriteFallback(
+        TestClientOutput output,
+        RendezvousConnectionOutcome outcome,
+        NetworkEndpoint? authoritativeFallback = null)
+    {
+        bool hasFallback = outcome.HasDedicatedFallback || authoritativeFallback is not null;
+        output.Write(
+        "join.fallback",
+        hasFallback ? "available" : "unavailable",
+        phase: "fallback",
+        outcome: outcome.Kind.ToString(),
+        endpointType: hasFallback ? "dedicated" : "none");
+    }
+
+    private static void WriteServiceFailure<T>(
+        TestClientOutput output,
+        string eventName,
+        string phase,
+        RendezvousClientResult<T> result) => output.WriteError(
+            eventName,
+            "failed",
+            SafeServiceMessage(result),
+            phase,
+            result.Error.ToString());
+
+    private static string SafeServiceMessage<T>(RendezvousClientResult<T> result) =>
+        $"Rendezvous returned {result.Error}.";
+
+    private static async Task ObserveCancellationAsync<T>(Task<T>? task)
+    {
+        if (task is null)
+        {
+            return;
+        }
+        try
+        {
+            await task.ConfigureAwait(false);
+        }
+        catch (OperationCanceledException)
+        {
+        }
+        catch (ObjectDisposedException)
+        {
+        }
+    }
+
+    private static string EndpointType(IPAddress address)
+    {
+        if (IPAddress.IsLoopback(address))
+        {
+            return "loopback";
+        }
+        if (address.AddressFamily == AddressFamily.InterNetworkV6)
+        {
+            byte[] ipv6 = address.GetAddressBytes();
+            return address.IsIPv6LinkLocal || (ipv6[0] & 0xfe) == 0xfc
+                ? "private"
+                : "public";
+        }
+        byte[] bytes = address.GetAddressBytes();
+        bool privateAddress = bytes[0] == 10
+            || bytes[0] == 172 && bytes[1] is >= 16 and <= 31
+            || bytes[0] == 192 && bytes[1] == 168;
+        return privateAddress ? "private" : "public";
+    }
+
+    private static long ToMilliseconds(TimeSpan elapsed) =>
+        (long)Math.Min(long.MaxValue, Math.Max(0, elapsed.TotalMilliseconds));
+
+    private sealed record SessionSelection(
+        SessionListing? Listing,
+        TestClientExitCode ExitCode);
+}

src/FinalFactory.Rendezvous.TestClient/TestClientApplication.cs

@@ -0,0 +1,95 @@
+namespace FinalFactory.Rendezvous.TestClient;
+
+internal enum TestClientExitCode
+{
+    Success = 0,
+    Usage = 2,
+    Configuration = 3,
+    ServiceFailure = 10,
+    NoCompatibleSession = 11,
+    TraversalFailed = 12,
+    DirectTrafficFailed = 13,
+    Cancelled = 130,
+}
+
+internal interface ITestClientCommandRunner
+{
+    Task<TestClientExitCode> RunAsync(
+        TestClientOptions options,
+        TestClientOutput output,
+        TextReader input,
+        CancellationToken cancellationToken);
+}
+
+internal sealed class TestClientApplication(ITestClientCommandRunner runner)
+{
+    private readonly ITestClientCommandRunner _runner = runner ?? throw new ArgumentNullException(nameof(runner));
+
+    internal async Task<int> RunAsync(
+        string[] args,
+        TextReader input,
+        TextWriter standardOutput,
+        TextWriter standardError,
+        CancellationToken cancellationToken)
+    {
+        bool jsonRequested = args.Contains("--json", StringComparer.Ordinal);
+        TestClientParseResult parsed = TestClientOptionParser.Parse(args);
+        TestClientOutput output = new(standardOutput, standardError, jsonRequested);
+        if (parsed.ShowHelp)
+        {
+            if (jsonRequested)
+            {
+                output.Write(
+                    "cli.help",
+                    "complete",
+                    phase: "configuration",
+                    message: "Run without --json to read the full command reference.");
+            }
+            else
+            {
+                await standardOutput.WriteLineAsync(TestClientOptionParser.Usage).ConfigureAwait(false);
+            }
+            return (int)TestClientExitCode.Success;
+        }
+        if (!parsed.Succeeded || parsed.Options is null)
+        {
+            if (jsonRequested)
+            {
+                output.WriteError(
+                    "cli.usage",
+                    "failed",
+                    parsed.Error ?? "Invalid command line.",
+                    phase: "configuration");
+            }
+            else
+            {
+                await standardError.WriteLineAsync(parsed.Error ?? "Invalid command line.").ConfigureAwait(false);
+                await standardError.WriteLineAsync("Use --help for documented options.").ConfigureAwait(false);
+            }
+            return (int)TestClientExitCode.Usage;
+        }
+
+        output = new TestClientOutput(standardOutput, standardError, parsed.Options.Json);
+        try
+        {
+            return (int)await _runner.RunAsync(
+                parsed.Options,
+                output,
+                input,
+                cancellationToken).ConfigureAwait(false);
+        }
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+        {
+            output.Write("lifecycle.cancelled", "cancelled", phase: "lifecycle");
+            return (int)TestClientExitCode.Cancelled;
+        }
+        catch (Exception exception)
+        {
+            output.WriteError(
+                "lifecycle.failed",
+                "failed",
+                $"Unexpected {exception.GetType().Name}; credentials remain redacted.");
+            return (int)TestClientExitCode.ServiceFailure;
+        }
+    }
+}

src/FinalFactory.Rendezvous.TestClient/TestClientOptions.cs

@@ -0,0 +1,377 @@
+using System.Net;
+using System.Net.Sockets;
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.TestClient;
+
+internal enum TestClientMode
+{
+    Host,
+    Browse,
+    Join,
+}
+
+internal sealed class TestClientOptions
+{
+    internal TestClientMode Mode { get; init; }
+    internal Uri ServiceUri { get; init; } = new("http://127.0.0.1:5000/");
+    internal IPEndPoint Mediator { get; init; } = new(IPAddress.Loopback, 9050);
+    internal GameId GameId { get; init; } = new("space-game");
+    internal EnvironmentId EnvironmentId { get; init; } = new("development");
+    internal RegionId RegionId { get; init; } = new("local");
+    internal uint ProtocolVersion { get; init; } = 1;
+    internal string BuildVersion { get; init; } = "test-client";
+    internal string DisplayName { get; init; } = "Rendezvous diagnostic host";
+    internal string PublisherCredentialEnvironmentVariable { get; init; } =
+        "RENDEZVOUS_PUBLISHER_CREDENTIAL";
+    internal Dictionary<string, string> Metadata { get; init; } = new(StringComparer.Ordinal);
+    internal NetworkEndpoint? DedicatedFallback { get; init; }
+    internal SessionListingId? ListingId { get; init; }
+    internal int LocalPort { get; init; }
+    internal int PageSize { get; init; } = 20;
+    internal TimeSpan OperationTimeout { get; init; } = TimeSpan.FromSeconds(20);
+    internal TimeSpan? RunDuration { get; init; }
+    internal bool Script { get; init; }
+    internal bool Json { get; init; }
+    internal bool ExitAfterEcho { get; init; }
+}
+
+internal sealed class TestClientParseResult
+{
+    private TestClientParseResult(TestClientOptions? options, string? error, bool showHelp)
+    {
+        Options = options;
+        Error = error;
+        ShowHelp = showHelp;
+    }
+
+    internal TestClientOptions? Options { get; }
+    internal string? Error { get; }
+    internal bool ShowHelp { get; }
+    internal bool Succeeded => Options is not null;
+
+    internal static TestClientParseResult Success(TestClientOptions options) => new(options, null, false);
+    internal static TestClientParseResult Failure(string error) => new(null, error, false);
+    internal static TestClientParseResult Help() => new(null, null, true);
+}
+
+internal static class TestClientOptionParser
+{
+    internal const string Usage = """
+        Rendezvous diagnostic client
+
+        Usage:
+          rendezvous-test-client host [options]
+          rendezvous-test-client browse [options]
+          rendezvous-test-client join [options]
+
+        Common options:
+          --service URL                 HTTP(S) Rendezvous base URL
+          --mediator IP:PORT            UDP mediator endpoint
+          --game ID                     Game scope (default: space-game)
+          --environment ID              Environment scope (default: development)
+          --protocol NUMBER             Exact gameplay protocol (default: 1)
+          --region ID                   Region filter/publication (default: local)
+          --timeout-seconds NUMBER      Bounded startup/traversal stage, 1-300 (default: 20)
+          --port NUMBER                 Caller-owned gameplay UDP port; 0 chooses one
+          --page-size NUMBER            Bounded browser page size, 1-100 (default: 20)
+          --script                      Never prompt; select the first compatible listing
+          --json                        Emit one versioned JSON event per line
+          --help                        Show this help
+
+        Host options:
+          --publisher-credential-env NAME  Environment variable containing the credential
+          --display-name TEXT           Public listing name
+          --build-version TEXT          Public build version
+          --metadata KEY=VALUE          Bounded public metadata; may be repeated
+          --fallback IP:PORT            Optional policy-authorized dedicated fallback
+          --run-seconds NUMBER          Stop after 1-86400 seconds
+          --exit-after-echo             Stop after an authenticated ping/echo/ack exchange
+
+        Join options:
+          --listing UUID                Join an exact listing; otherwise browse/select
+
+        Credentials are accepted only through the named environment variable. They are never
+        accepted on the command line and are never written to human or JSON output.
+        """;
+
+    internal static TestClientParseResult Parse(string[] args)
+    {
+        if (args.Length == 0 || args.Length == 1 && IsHelp(args[0]))
+        {
+            return TestClientParseResult.Help();
+        }
+        if (args.Length > 64)
+        {
+            return TestClientParseResult.Failure("Too many command-line arguments.");
+        }
+        if (!TryMode(args[0], out TestClientMode mode))
+        {
+            return TestClientParseResult.Failure("The first argument must be host, browse, or join.");
+        }
+
+        Uri serviceUri = new("http://127.0.0.1:5000/");
+        IPEndPoint mediator = new(IPAddress.Loopback, 9050);
+        string game = "space-game";
+        string environment = "development";
+        string region = "local";
+        uint protocol = 1;
+        string buildVersion = "test-client";
+        string displayName = "Rendezvous diagnostic host";
+        string credentialEnvironmentVariable = "RENDEZVOUS_PUBLISHER_CREDENTIAL";
+        Dictionary<string, string> metadata = new(StringComparer.Ordinal);
+        NetworkEndpoint? dedicatedFallback = null;
+        SessionListingId? listingId = null;
+        int localPort = 0;
+        int pageSize = 20;
+        int timeoutSeconds = 20;
+        int? runSeconds = null;
+        bool script = false;
+        bool json = false;
+        bool exitAfterEcho = false;
+        HashSet<string> seen = new(StringComparer.Ordinal);
+
+        for (int index = 1; index < args.Length; index++)
+        {
+            string option = args[index];
+            if (IsHelp(option))
+            {
+                return TestClientParseResult.Help();
+            }
+            if (option is "--script" or "--json" or "--exit-after-echo")
+            {
+                if (!seen.Add(option))
+                {
+                    return TestClientParseResult.Failure($"Option {option} was specified more than once.");
+                }
+                script |= option == "--script";
+                json |= option == "--json";
+                exitAfterEcho |= option == "--exit-after-echo";
+                continue;
+            }
+            if (!option.StartsWith("--", StringComparison.Ordinal)
+                || index + 1 >= args.Length)
+            {
+                return TestClientParseResult.Failure("Every option must use the form --name value.");
+            }
+
+            string value = args[++index];
+            if (value.Length is 0 or > 512)
+            {
+                return TestClientParseResult.Failure($"Option {option} has an invalid value length.");
+            }
+            if (option != "--metadata" && !seen.Add(option))
+            {
+                return TestClientParseResult.Failure($"Option {option} was specified more than once.");
+            }
+
+            switch (option)
+            {
+                case "--service":
+                    if (!TryServiceUri(value, out serviceUri))
+                    {
+                        return TestClientParseResult.Failure("The service URL must be absolute HTTP(S), credential-free, and query-free.");
+                    }
+                    break;
+                case "--mediator":
+                    if (!IPEndPoint.TryParse(value, out IPEndPoint? parsedMediator)
+                        || parsedMediator.Port == 0)
+                    {
+                        return TestClientParseResult.Failure("The mediator must be an IP endpoint with a non-zero port.");
+                    }
+                    mediator = parsedMediator;
+                    break;
+                case "--game":
+                    game = value;
+                    break;
+                case "--environment":
+                    environment = value;
+                    break;
+                case "--region":
+                    region = value;
+                    break;
+                case "--protocol":
+                    if (!uint.TryParse(value, out protocol) || protocol == 0)
+                    {
+                        return TestClientParseResult.Failure("The protocol must be a positive integer.");
+                    }
+                    break;
+                case "--build-version":
+                    buildVersion = value;
+                    break;
+                case "--display-name":
+                    displayName = value;
+                    break;
+                case "--publisher-credential-env":
+                    if (!IsEnvironmentVariableName(value))
+                    {
+                        return TestClientParseResult.Failure("The credential environment-variable name is invalid.");
+                    }
+                    credentialEnvironmentVariable = value;
+                    break;
+                case "--metadata":
+                    if (!TryMetadata(value, metadata))
+                    {
+                        return TestClientParseResult.Failure("Metadata must be a unique KEY=VALUE pair with a non-empty key.");
+                    }
+                    break;
+                case "--fallback":
+                    if (!IPEndPoint.TryParse(value, out IPEndPoint? fallbackEndpoint)
+                        || fallbackEndpoint.Port == 0)
+                    {
+                        return TestClientParseResult.Failure("The fallback must be an IP endpoint with a non-zero port.");
+                    }
+                    dedicatedFallback = new NetworkEndpoint
+                    {
+                        AddressFamily = fallbackEndpoint.AddressFamily == AddressFamily.InterNetwork
+                            ? AddressFamilyKind.Ipv4
+                            : AddressFamilyKind.Ipv6,
+                        Address = fallbackEndpoint.Address.ToString(),
+                        Port = fallbackEndpoint.Port,
+                    };
+                    break;
+                case "--listing":
+                    if (!Guid.TryParse(value, out Guid parsedListing) || parsedListing == Guid.Empty)
+                    {
+                        return TestClientParseResult.Failure("The listing must be a non-empty UUID.");
+                    }
+                    listingId = new SessionListingId(parsedListing);
+                    break;
+                case "--port":
+                    if (!int.TryParse(value, out localPort) || localPort is < 0 or > 65_535)
+                    {
+                        return TestClientParseResult.Failure("The local UDP port must be between 0 and 65535.");
+                    }
+                    break;
+                case "--page-size":
+                    if (!int.TryParse(value, out pageSize)
+                        || pageSize is < 1 or > ContractLimits.BrowserPageMaxItems)
+                    {
+                        return TestClientParseResult.Failure("The page size is outside the contract limit.");
+                    }
+                    break;
+                case "--timeout-seconds":
+                    if (!int.TryParse(value, out timeoutSeconds) || timeoutSeconds is < 1 or > 300)
+                    {
+                        return TestClientParseResult.Failure("The timeout must be between 1 and 300 seconds.");
+                    }
+                    break;
+                case "--run-seconds":
+                    if (!int.TryParse(value, out int parsedRunSeconds)
+                        || parsedRunSeconds is < 1 or > 86_400)
+                    {
+                        return TestClientParseResult.Failure("The host run duration must be between 1 and 86400 seconds.");
+                    }
+                    runSeconds = parsedRunSeconds;
+                    break;
+                default:
+                    return TestClientParseResult.Failure($"Unknown option {option}.");
+            }
+        }
+
+        if (!IsSlug(game, ContractLimits.GameIdMaxCharacters)
+            || !IsSlug(environment, ContractLimits.EnvironmentIdMaxCharacters)
+            || !IsSlug(region, ContractLimits.RegionIdMaxCharacters)
+            || !ContractValidation.IsBuildVersionValid(buildVersion)
+            || !ContractValidation.IsDisplayNameValid(displayName)
+            || !ContractValidation.IsMetadataValid(metadata))
+        {
+            return TestClientParseResult.Failure("One or more game, environment, region, build, or display values violate v1 limits.");
+        }
+        if (listingId.HasValue && mode != TestClientMode.Join
+            || runSeconds.HasValue && mode != TestClientMode.Host
+            || exitAfterEcho && mode != TestClientMode.Host
+            || metadata.Count > 0 && mode != TestClientMode.Host
+            || dedicatedFallback is not null && mode != TestClientMode.Host
+            || seen.Contains("--publisher-credential-env") && mode != TestClientMode.Host
+            || seen.Contains("--display-name") && mode != TestClientMode.Host
+            || seen.Contains("--build-version") && mode != TestClientMode.Host)
+        {
+            return TestClientParseResult.Failure("One or more options do not apply to the selected mode.");
+        }
+
+        return TestClientParseResult.Success(new TestClientOptions
+        {
+            Mode = mode,
+            ServiceUri = serviceUri,
+            Mediator = mediator,
+            GameId = new(game),
+            EnvironmentId = new(environment),
+            RegionId = new(region),
+            ProtocolVersion = protocol,
+            BuildVersion = buildVersion,
+            DisplayName = displayName,
+            PublisherCredentialEnvironmentVariable = credentialEnvironmentVariable,
+            Metadata = metadata,
+            DedicatedFallback = dedicatedFallback,
+            ListingId = listingId,
+            LocalPort = localPort,
+            PageSize = pageSize,
+            OperationTimeout = TimeSpan.FromSeconds(timeoutSeconds),
+            RunDuration = runSeconds.HasValue
+                ? TimeSpan.FromSeconds(runSeconds.Value)
+                : mode == TestClientMode.Host && script
+                    ? TimeSpan.FromSeconds(timeoutSeconds)
+                    : null,
+            Script = script,
+            Json = json,
+            ExitAfterEcho = exitAfterEcho,
+        });
+    }
+
+    private static bool TryMode(string value, out TestClientMode mode) =>
+        Enum.TryParse(value, true, out mode) && Enum.IsDefined(mode);
+
+    private static bool IsHelp(string value) => value is "--help" or "-h" or "help";
+
+    private static bool TryServiceUri(string value, out Uri uri)
+    {
+        uri = null!;
+        if (!Uri.TryCreate(value, UriKind.Absolute, out Uri? parsed)
+            || parsed.Scheme is not ("http" or "https")
+            || !string.IsNullOrEmpty(parsed.UserInfo)
+            || !string.IsNullOrEmpty(parsed.Query)
+            || !string.IsNullOrEmpty(parsed.Fragment))
+        {
+            return false;
+        }
+
+        UriBuilder builder = new(parsed) { Path = parsed.AbsolutePath.TrimEnd('/') + "/" };
+        uri = builder.Uri;
+        return true;
+    }
+
+    private static bool IsEnvironmentVariableName(string value)
+    {
+        if (value.Length is 0 or > 64 || !(char.IsLetter(value[0]) || value[0] == '_'))
+        {
+            return false;
+        }
+        return value.All(static character =>
+            char.IsAsciiLetterOrDigit(character) || character == '_');
+    }
+
+    private static bool TryMetadata(string value, Dictionary<string, string> metadata)
+    {
+        int separator = value.IndexOf('=');
+        if (separator is < 1 or > ContractLimits.MetadataKeyMaxBytes
+            || metadata.Count >= ContractLimits.MetadataMaxKeys)
+        {
+            return false;
+        }
+        string key = value[..separator];
+        string metadataValue = value[(separator + 1)..];
+        return !string.IsNullOrWhiteSpace(key)
+            && ContractValidation.IsUtf8LengthWithin(key, ContractLimits.MetadataKeyMaxBytes)
+            && ContractValidation.IsUtf8LengthWithin(metadataValue, ContractLimits.MetadataValueMaxBytes)
+            && metadata.TryAdd(key, metadataValue);
+    }
+
+    private static bool IsSlug(string value, int maximumCharacters) =>
+        value.Length is > 0
+        && value.Length <= maximumCharacters
+        && value[0] is >= 'a' and <= 'z'
+        && value.All(static character => character is >= 'a' and <= 'z'
+            or >= '0' and <= '9'
+            or '-');
+}

src/FinalFactory.Rendezvous.TestClient/TestClientOutput.cs

@@ -0,0 +1,181 @@
+using System.Globalization;
+using System.Text;
+using System.Text.Json;
+
+namespace FinalFactory.Rendezvous.TestClient;
+
+internal sealed class TestClientOutput(TextWriter standardOutput, TextWriter standardError, bool json)
+{
+    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
+    {
+        WriteIndented = false,
+    };
+
+    private readonly object _gate = new();
+    private readonly TextWriter _standardOutput = standardOutput ?? throw new ArgumentNullException(nameof(standardOutput));
+    private readonly TextWriter _standardError = standardError ?? throw new ArgumentNullException(nameof(standardError));
+    private readonly bool _json = json;
+
+    internal void Write(
+        string eventName,
+        string status,
+        string? phase = null,
+        string? listingId = null,
+        string? displayName = null,
+        string? outcome = null,
+        string? endpointType = null,
+        int? count = null,
+        long? elapsedMilliseconds = null,
+        string? message = null) => WriteCore(
+            _standardOutput,
+            new TestClientEvent
+            {
+                Event = SafeToken(eventName) ?? string.Empty,
+                Status = SafeToken(status) ?? string.Empty,
+                Phase = SafeToken(phase),
+                ListingId = SafeToken(listingId),
+                DisplayName = SafeText(displayName),
+                Outcome = SafeToken(outcome),
+                EndpointType = SafeToken(endpointType),
+                Count = count,
+                ElapsedMilliseconds = elapsedMilliseconds,
+                Message = SafeText(message),
+            });
+
+    internal void WriteError(
+        string eventName,
+        string status,
+        string message,
+        string? phase = null,
+        string? outcome = null) => WriteCore(
+            _standardError,
+            new TestClientEvent
+            {
+                Event = SafeToken(eventName) ?? string.Empty,
+                Status = SafeToken(status) ?? string.Empty,
+                Phase = SafeToken(phase),
+                Outcome = SafeToken(outcome),
+                Message = SafeText(message),
+            });
+
+    internal void WritePrompt(string prompt)
+    {
+        if (_json)
+        {
+            return;
+        }
+        lock (_gate)
+        {
+            _standardOutput.Write(SafeText(prompt));
+            _standardOutput.Flush();
+        }
+    }
+
+    private void WriteCore(TextWriter writer, TestClientEvent item)
+    {
+        string line = _json
+            ? JsonSerializer.Serialize(item, JsonOptions)
+            : HumanLine(item);
+        lock (_gate)
+        {
+            writer.WriteLine(line);
+            writer.Flush();
+        }
+    }
+
+    private static string HumanLine(TestClientEvent item)
+    {
+        StringBuilder line = new();
+        line.Append('[').Append(item.Status).Append("] ").Append(item.Event);
+        Append(line, "phase", item.Phase);
+        Append(line, "listing", item.ListingId);
+        Append(line, "name", item.DisplayName, quote: true);
+        Append(line, "outcome", item.Outcome);
+        Append(line, "endpoint", item.EndpointType);
+        if (item.Count.HasValue)
+        {
+            Append(line, "count", item.Count.Value.ToString(System.Globalization.CultureInfo.InvariantCulture));
+        }
+        if (item.ElapsedMilliseconds.HasValue)
+        {
+            Append(
+                line,
+                "elapsedMs",
+                item.ElapsedMilliseconds.Value.ToString(System.Globalization.CultureInfo.InvariantCulture));
+        }
+        Append(line, "message", item.Message, quote: true);
+        return line.ToString();
+    }
+
+    private static void Append(
+        StringBuilder builder,
+        string name,
+        string? value,
+        bool quote = false)
+    {
+        if (!string.IsNullOrEmpty(value))
+        {
+            builder.Append(' ').Append(name).Append('=');
+            if (quote)
+            {
+                builder.Append('"').Append(value.Replace("\\", "\\\\", StringComparison.Ordinal)
+                    .Replace("\"", "\\\"", StringComparison.Ordinal)).Append('"');
+            }
+            else
+            {
+                builder.Append(value);
+            }
+        }
+    }
+
+    private static string? SafeToken(string? value)
+    {
+        if (value is null)
+        {
+            return null;
+        }
+        return new string(value
+            .Take(96)
+            .Select(static character => char.IsAsciiLetterOrDigit(character)
+                || character is '.' or '-' or '_' or ':'
+                    ? char.ToLowerInvariant(character)
+                    : '_')
+            .ToArray());
+    }
+
+    private static string? SafeText(string? value)
+    {
+        if (value is null)
+        {
+            return null;
+        }
+        return new string(value
+            .Take(160)
+            .Select(static character => IsUnsafeHumanCharacter(character) ? '?' : character)
+            .ToArray());
+    }
+
+    private static bool IsUnsafeHumanCharacter(char character) =>
+        char.GetUnicodeCategory(character) is
+            UnicodeCategory.Control
+            or UnicodeCategory.Format
+            or UnicodeCategory.LineSeparator
+            or UnicodeCategory.ParagraphSeparator
+            or UnicodeCategory.Surrogate
+            or UnicodeCategory.PrivateUse;
+
+    private sealed class TestClientEvent
+    {
+        public int Version { get; init; } = 1;
+        public string Event { get; init; } = string.Empty;
+        public string Status { get; init; } = string.Empty;
+        public string? Phase { get; init; }
+        public string? ListingId { get; init; }
+        public string? DisplayName { get; init; }
+        public string? Outcome { get; init; }
+        public string? EndpointType { get; init; }
+        public int? Count { get; init; }
+        public long? ElapsedMilliseconds { get; init; }
+        public string? Message { get; init; }
+    }
+}

tests/FinalFactory.Rendezvous.Capacity/CapacityOptions.cs

@@ -0,0 +1,91 @@
+namespace FinalFactory.Rendezvous.Capacity;
+
+internal sealed record CapacityOptions
+{
+    public required string Profile { get; init; }
+    public required int Listings { get; init; }
+    public required int Attempts { get; init; }
+    public required int Samples { get; init; }
+    public required int SoakCycles { get; init; }
+    public required int SoakSeconds { get; init; }
+    public string? OutputPath { get; init; }
+
+    public static CapacityOptions Parse(string[] args)
+    {
+        Dictionary<string, string> values = ParseArguments(args);
+        string profile = values.GetValueOrDefault("--profile") ?? "quick";
+        (int listings, int attempts, int samples, int soakCycles, int soakSeconds) = profile switch
+        {
+            "quick" => (1_000, 500, 100, 20, 0),
+            "candidate" => (25_000, 10_000, 1_000, 1_000, 300),
+            _ => throw new ArgumentException("--profile must be 'quick' or 'candidate'."),
+        };
+
+        return new()
+        {
+            Profile = profile,
+            Listings = ParsePositive(values.GetValueOrDefault("--listings"), listings, "--listings"),
+            Attempts = ParsePositive(values.GetValueOrDefault("--attempts"), attempts, "--attempts"),
+            Samples = ParsePositive(values.GetValueOrDefault("--samples"), samples, "--samples"),
+            SoakCycles = ParsePositive(
+                values.GetValueOrDefault("--soak-cycles"),
+                soakCycles,
+                "--soak-cycles"),
+            SoakSeconds = ParseNonNegative(
+                values.GetValueOrDefault("--soak-seconds"),
+                soakSeconds,
+                "--soak-seconds"),
+            OutputPath = values.GetValueOrDefault("--output"),
+        };
+    }
+
+    private static Dictionary<string, string> ParseArguments(string[] args)
+    {
+        HashSet<string> allowed =
+        [
+            "--profile",
+            "--listings",
+            "--attempts",
+            "--samples",
+            "--soak-cycles",
+            "--soak-seconds",
+            "--output",
+        ];
+        Dictionary<string, string> values = new(StringComparer.Ordinal);
+        for (int index = 0; index < args.Length; index += 2)
+        {
+            string option = args[index];
+            if (!allowed.Contains(option))
+            {
+                throw new ArgumentException($"Unknown option: {option}.");
+            }
+
+            if (index == args.Length - 1
+                || args[index + 1].StartsWith("--", StringComparison.Ordinal))
+            {
+                throw new ArgumentException($"{option} requires a value.");
+            }
+
+            if (!values.TryAdd(option, args[index + 1]))
+            {
+                throw new ArgumentException($"{option} may be supplied only once.");
+            }
+        }
+
+        return values;
+    }
+
+    private static int ParsePositive(string? value, int fallback, string option) =>
+        value is null
+            ? fallback
+            : int.TryParse(value, out int parsed) && parsed > 0
+                ? parsed
+                : throw new ArgumentException($"{option} must be a positive integer.");
+
+    private static int ParseNonNegative(string? value, int fallback, string option) =>
+        value is null
+            ? fallback
+            : int.TryParse(value, out int parsed) && parsed >= 0
+                ? parsed
+                : throw new ArgumentException($"{option} must be a non-negative integer.");
+}

tests/FinalFactory.Rendezvous.Capacity/CapacityReport.cs

@@ -0,0 +1,76 @@
+namespace FinalFactory.Rendezvous.Capacity;
+
+internal sealed record CapacityReport
+{
+    public required int SchemaVersion { get; init; }
+    public required string EvidenceVersion { get; init; }
+    public required DateTimeOffset GeneratedAt { get; init; }
+    public required string Profile { get; init; }
+    public required RuntimeEvidence Runtime { get; init; }
+    public required CapacityTargets Targets { get; init; }
+    public required IReadOnlyList<CapacityMeasurement> Measurements { get; init; }
+    public required StateEvidence State { get; init; }
+    public required IReadOnlyList<string> Failures { get; init; }
+    public required bool Passed { get; init; }
+}
+
+internal sealed record RuntimeEvidence(
+    string Framework,
+    string OperatingSystem,
+    string Kernel,
+    string Architecture,
+    string CpuModel,
+    int ProcessorCount,
+    string CpuAffinity,
+    string CpuQuota,
+    string MemoryLimit,
+    string GarbageCollector,
+    string CommitSha,
+    string TreeState,
+    string Command,
+    string ImageDigest,
+    string WorkloadSeed,
+    double CapacityPhaseAverageCpuPercent,
+    long PeakWorkingSetBytes,
+    long ManagedBytesAfterCleanup);
+
+internal sealed record CapacityTargets(
+    int VisibleListings,
+    int ActiveJoinAttempts,
+    int CoreControlOperationsPerSecond,
+    int CoreMediationOperationsPerSecond,
+    double CoreControlP95Milliseconds,
+    double CoreMediationP95Milliseconds,
+    double MaximumAverageCpuPercent,
+    long MaximumWorkingSetBytes,
+    int SoakCycles,
+    int SoakDurationSeconds);
+
+internal sealed record CapacityMeasurement(
+    string Operation,
+    int Samples,
+    double P50Milliseconds,
+    double P95Milliseconds,
+    double P99Milliseconds,
+    double OperationsPerSecond,
+    double MinimumOperationsPerSecond,
+    double BudgetMilliseconds,
+    bool Passed);
+
+internal sealed record StateEvidence(
+    int PeakListings,
+    int PeakAttempts,
+    int PeakReplayMarkers,
+    int FinalListings,
+    int FinalAttempts,
+    int FinalReplayMarkers,
+    long ExpiryChurn,
+    long MaintenanceSweeps,
+    int SoakCyclesCompleted,
+    double SoakDurationSeconds,
+    int SoakPeakScheduledExpiryEntries,
+    long SoakManagedGrowthBytes,
+    int SoakHandleGrowth,
+    bool RestartStartedEmpty,
+    bool OverloadWasTyped,
+    bool RecoverySucceeded);

tests/FinalFactory.Rendezvous.Capacity/CapacityRunner.cs

@@ -0,0 +1,580 @@
+using System.Collections.Concurrent;
+using System.Diagnostics;
+using System.Runtime;
+using System.Runtime.InteropServices;
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Observability;
+using FinalFactory.Rendezvous.Server.State;
+
+namespace FinalFactory.Rendezvous.Capacity;
+
+internal static class CapacityRunner
+{
+    private static readonly TenantScope Scope = new(new("space-game"), new("production"));
+    private const uint ProtocolVersion = 1;
+
+    public static Task<CapacityReport> RunAsync(CapacityOptions options)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        Process process = Process.GetCurrentProcess();
+        TimeSpan cpuBefore = process.TotalProcessorTime;
+        Stopwatch capacityPhaseTime = Stopwatch.StartNew();
+        List<string> failures = [];
+        List<CapacityMeasurement> measurements = [];
+        ManualClock clock = new();
+        InMemoryEphemeralRendezvousStore store = CreateStore(options, clock);
+        List<StoredListing> listings = new(options.Listings);
+        List<CreateJoinAttemptCommand> attempts = new(options.Attempts);
+        int registrationSamples = Math.Min(options.Samples, options.Listings);
+        int attemptSamples = Math.Min(options.Samples, options.Attempts);
+
+        for (int index = 0; index < options.Listings - registrationSamples; index++)
+        {
+            listings.Add(CreateVisibleListing(store, index));
+        }
+
+        measurements.Add(Measure(
+            "registration-and-presence",
+            registrationSamples,
+            budgetMilliseconds: 200,
+            minimumOperationsPerSecond: 200,
+            index => listings.Add(CreateVisibleListing(
+                store,
+                options.Listings - registrationSamples + index))));
+
+        measurements.Add(Measure(
+            "lease-renewal",
+            registrationSamples,
+            budgetMilliseconds: 200,
+            minimumOperationsPerSecond: 200,
+            index =>
+            {
+                StoredListing listing = listings[index];
+                StoreResult<StoredListing> renewed = store.RenewLease(new(
+                    listing.Definition.ListingId,
+                    listing.Definition.LeaseId,
+                    listing.Definition.LeaseFingerprint,
+                    listing.Definition.OwnerSubject,
+                    listing.Version));
+                RequireSuccess(renewed, "renewal");
+                listings[index] = renewed.Value!;
+            }));
+
+        int browseSamples = Math.Min(options.Samples, 250);
+        measurements.Add(Measure(
+            "visible-session-browse",
+            browseSamples,
+            budgetMilliseconds: 200,
+            minimumOperationsPerSecond: 200,
+            _ => RequireSuccess(
+                store.BrowseVisibleListings(new(
+                    Scope,
+                    ProtocolVersion,
+                    new RegionId("eu-central"),
+                    ContractLimits.BrowserPageMaxItems,
+                    ExcludeFull: true)),
+                "browse")));
+
+        for (int index = 0; index < options.Attempts - attemptSamples; index++)
+        {
+            CreateJoinAttemptCommand command = CreateAttempt(index, listings[index % listings.Count]);
+            RequireSuccess(store.CreateJoinAttempt(command), "join issuance");
+            attempts.Add(command);
+        }
+
+        measurements.Add(Measure(
+            "join-attempt-issuance",
+            attemptSamples,
+            budgetMilliseconds: 200,
+            minimumOperationsPerSecond: 200,
+            index =>
+            {
+                int sequence = options.Attempts - attemptSamples + index;
+                CreateJoinAttemptCommand command = CreateAttempt(
+                    sequence,
+                    listings[sequence % listings.Count]);
+                RequireSuccess(store.CreateJoinAttempt(command), "join issuance");
+                attempts.Add(command);
+            }));
+
+        int punchSamples = Math.Min(options.Samples, attempts.Count);
+        measurements.Add(MeasureConcurrentPunch(store, attempts, punchSamples));
+        EphemeralStoreSnapshot peak = store.GetSnapshot();
+
+        StoreResult<StoredJoinAttempt> overloaded = store.CreateJoinAttempt(
+            CreateAttempt(options.Attempts + 1, listings[^1]));
+        bool overloadWasTyped = peak.ActiveJoinAttempts == options.Attempts
+            && overloaded.Code == StoreResultCode.CapacityExceeded;
+        if (!overloadWasTyped)
+        {
+            failures.Add(
+                $"Expected typed CapacityExceeded at {options.Attempts} active attempts, "
+                + $"observed count={peak.ActiveJoinAttempts}, result={overloaded.Code}.");
+        }
+
+        int revocationSamples = Math.Min(Math.Max(1, options.Samples / 20), listings.Count / 2);
+        measurements.Add(Measure(
+            "principal-revocation",
+            revocationSamples,
+            budgetMilliseconds: 200,
+            minimumOperationsPerSecond: 50,
+            index => RequireSuccess(
+                store.RevokePrincipal(
+                    listings[index].Definition.OwnerSubject,
+                    TimeSpan.FromMinutes(1)),
+                "principal revocation")));
+
+        using (RendezvousTelemetry telemetry = new(store))
+        {
+            measurements.Add(Measure(
+                "telemetry-recording",
+                Math.Max(100, options.Samples),
+                budgetMilliseconds: 1,
+                minimumOperationsPerSecond: 10_000,
+                _ =>
+                {
+                    telemetry.RecordHttp("browse", 200, 1);
+                    telemetry.RecordUdp("contribution", "accepted", 1);
+                    telemetry.RecordPairingLatency(2);
+                }));
+        }
+
+        clock.Advance(TimeSpan.FromSeconds(61));
+        EphemeralStoreSnapshot? afterCoincidentExpiry = null;
+        measurements.Add(Measure(
+            "coincident-listing-attempt-expiry",
+            samples: 1,
+            budgetMilliseconds: 200,
+            minimumOperationsPerSecond: 0,
+            _ => afterCoincidentExpiry = store.GetSnapshot()));
+        if (afterCoincidentExpiry!.ActiveJoinAttempts != 0
+            || afterCoincidentExpiry.ActiveListings != 0)
+        {
+            failures.Add("Coincident 60-second cleanup retained expired listings or join attempts.");
+        }
+
+        clock.Advance(TimeSpan.FromSeconds(90));
+        _ = store.GetSnapshot();
+        StoredListing recoveryListing = CreateVisibleListing(store, options.Listings + 1);
+        StoreResult<StoredJoinAttempt> recovered = store.CreateJoinAttempt(
+            CreateAttempt(options.Attempts + 2, recoveryListing));
+        bool recoverySucceeded = recovered.Succeeded;
+        if (!recoverySucceeded)
+        {
+            failures.Add($"Store did not recover after attempt expiry: {recovered.Code}.");
+        }
+
+        clock.Advance(TimeSpan.FromSeconds(151));
+        EphemeralStoreSnapshot final = store.GetSnapshot();
+        if (final.ActiveListings != 0
+            || final.ActiveJoinAttempts != 0
+            || final.ReplayMarkers != 0
+            || final.IdempotencyEntries != 0
+            || final.RetainedOutcomeReports != 0)
+        {
+            failures.Add("Expiry cleanup left active or retained state after every configured deadline.");
+        }
+
+        capacityPhaseTime.Stop();
+        process.Refresh();
+        double capacityPhaseCpuPercent = 100
+            * (process.TotalProcessorTime - cpuBefore).TotalSeconds
+            / Math.Max(capacityPhaseTime.Elapsed.TotalSeconds * Environment.ProcessorCount, 0.000_001);
+        if (options.Profile == "candidate" && capacityPhaseCpuPercent > 70)
+        {
+            failures.Add(
+                $"Capacity-phase CPU {capacityPhaseCpuPercent:F1}% exceeded the 70% candidate budget.");
+        }
+
+        SoakEvidence soak = RunAcceleratedSoak(options, failures);
+        ManualClock restartClock = new();
+        EphemeralStoreSnapshot restarted = CreateStore(options, restartClock).GetSnapshot();
+        bool restartStartedEmpty = restarted.ActiveListings == 0
+            && restarted.ActiveJoinAttempts == 0
+            && restarted.ReplayMarkers == 0;
+        if (!restartStartedEmpty)
+        {
+            failures.Add("A restarted store did not begin empty.");
+        }
+
+        foreach (CapacityMeasurement measurement in measurements.Where(static item => !item.Passed))
+        {
+            failures.Add(
+                $"{measurement.Operation} missed its budget: p95={measurement.P95Milliseconds:F3} ms, "
+                + $"rate={measurement.OperationsPerSecond:F1}/s.");
+        }
+
+        GC.Collect();
+        GC.WaitForPendingFinalizers();
+        GC.Collect();
+        process.Refresh();
+        long managedAfterCleanup = GC.GetTotalMemory(forceFullCollection: true);
+        long memoryBudget = 1_610_612_736;
+        if (process.PeakWorkingSet64 > memoryBudget)
+        {
+            failures.Add(
+                $"Peak working set {process.PeakWorkingSet64} exceeded the 1.5 GiB profile budget.");
+        }
+
+        if (options.Profile == "candidate" && Environment.ProcessorCount != 2)
+        {
+            failures.Add(
+                $"Candidate evidence must expose exactly two CPUs; runtime exposed "
+                + $"{Environment.ProcessorCount}.");
+        }
+
+        CapacityReport report = new()
+        {
+            SchemaVersion = 2,
+            EvidenceVersion = "v2",
+            GeneratedAt = DateTimeOffset.UtcNow,
+            Profile = options.Profile,
+            Runtime = new(
+                RuntimeInformation.FrameworkDescription,
+                RuntimeInformation.OSDescription,
+                Environment.OSVersion.VersionString,
+                RuntimeInformation.ProcessArchitecture.ToString(),
+                ReadCpuModel(),
+                Environment.ProcessorCount,
+                Environment.GetEnvironmentVariable("RENDEZVOUS_EVIDENCE_CPUSET") ?? "unrestricted",
+                ReadCgroupValue("/sys/fs/cgroup/cpu.max"),
+                ReadCgroupValue("/sys/fs/cgroup/memory.max"),
+                GCSettings.IsServerGC ? "server" : "workstation",
+                Environment.GetEnvironmentVariable("RENDEZVOUS_EVIDENCE_COMMIT") ?? "unrecorded",
+                Environment.GetEnvironmentVariable("RENDEZVOUS_EVIDENCE_TREE_STATE") ?? "unrecorded",
+                Environment.GetEnvironmentVariable("RENDEZVOUS_EVIDENCE_COMMAND") ?? "unrecorded",
+                Environment.GetEnvironmentVariable("RENDEZVOUS_EVIDENCE_IMAGE_DIGEST") ?? "not-containerized",
+                "fixed-sequences-random-identifiers",
+                capacityPhaseCpuPercent,
+                process.PeakWorkingSet64,
+                managedAfterCleanup),
+            Targets = new(
+                options.Listings,
+                options.Attempts,
+                200,
+                2_000,
+                200,
+                100,
+                70,
+                memoryBudget,
+                options.SoakCycles,
+                options.SoakSeconds),
+            Measurements = measurements,
+            State = new(
+                peak.ActiveListings,
+                peak.ActiveJoinAttempts,
+                peak.ReplayMarkers,
+                final.ActiveListings,
+                final.ActiveJoinAttempts,
+                final.ReplayMarkers,
+                final.ExpiryChurn,
+                final.MaintenanceSweeps,
+                soak.Cycles,
+                soak.Duration.TotalSeconds,
+                soak.PeakScheduledExpiryEntries,
+                soak.ManagedGrowthBytes,
+                soak.HandleGrowth,
+                restartStartedEmpty,
+                overloadWasTyped,
+                recoverySucceeded),
+            Failures = failures,
+            Passed = failures.Count == 0,
+        };
+        return Task.FromResult(report);
+    }
+
+    private static InMemoryEphemeralRendezvousStore CreateStore(
+        CapacityOptions options,
+        ManualClock clock) => new(
+        new EphemeralStoreOptions
+        {
+            MaxListings = options.Listings,
+            MaxPresenceBindings = options.Listings,
+            MaxJoinAttempts = options.Attempts,
+            MaxOutcomeReports = options.Attempts,
+            MaxIdempotencyEntries = options.Listings + options.Attempts + 1,
+        },
+        clock,
+        clock);
+
+    private static StoredListing CreateVisibleListing(
+        InMemoryEphemeralRendezvousStore store,
+        int sequence)
+    {
+        string owner = $"publisher-{sequence}";
+        SecretFingerprint leaseFingerprint = new($"lease-{sequence}");
+        SecretFingerprint presenceFingerprint = new($"presence-{sequence}");
+        ListingDefinition definition = new()
+        {
+            ListingId = new(Guid.NewGuid()),
+            LeaseId = new(Guid.NewGuid()),
+            Scope = Scope,
+            OwnerSubject = owner,
+            RegionId = new("eu-central"),
+            ProtocolVersion = ProtocolVersion,
+            BuildVersion = "1.0.0",
+            DisplayName = $"Capacity host {sequence}",
+            Visibility = ListingVisibility.Public,
+            TrustMode = PublisherTrustMode.ManagedDedicated,
+            CurrentPlayers = 1,
+            MaximumPlayers = 8,
+            Metadata = new Dictionary<string, string>(StringComparer.Ordinal),
+            LeaseFingerprint = leaseFingerprint,
+            HostPresenceHandle = new(Guid.NewGuid()),
+            HostPresenceFingerprint = presenceFingerprint,
+            CapabilityDerivationSalt = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
+        };
+        StoreResult<StoredListing> created = store.CreateListing(new(
+            $"register-{sequence}",
+            $"register-request-{sequence}",
+            definition));
+        RequireSuccess(created, "registration");
+        StoreResult<StoredListing> bound = store.BindHostPresence(new(
+            definition.HostPresenceHandle,
+            presenceFingerprint,
+            PublicEndpoint(10_000 + sequence % 50_000),
+            null));
+        RequireSuccess(bound, "host presence");
+        return bound.Value!;
+    }
+
+    private static CreateJoinAttemptCommand CreateAttempt(int sequence, StoredListing listing) => new()
+    {
+        IdempotencyOwner = $"client-{sequence}",
+        IdempotencyKey = $"join-{sequence}",
+        RequestFingerprint = $"join-request-{sequence}",
+        ClientSubject = $"client-{sequence}",
+        AttemptId = new(Guid.NewGuid()),
+        MediationHandle = new(Guid.NewGuid()),
+        Scope = Scope,
+        ListingId = listing.Definition.ListingId,
+        ProtocolVersion = ProtocolVersion,
+        HostCapabilityFingerprint = new($"host-capability-{sequence}"),
+        ClientCapabilityFingerprint = new($"client-capability-{sequence}"),
+        ConnectionTicketFingerprint = new($"ticket-{sequence}"),
+        CapabilityDerivationSalt = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
+    };
+
+    private static CapacityMeasurement MeasureConcurrentPunch(
+        InMemoryEphemeralRendezvousStore store,
+        List<CreateJoinAttemptCommand> attempts,
+        int samples)
+    {
+        ConcurrentBag<double> latencies = [];
+        Stopwatch total = Stopwatch.StartNew();
+        Parallel.ForEach(
+            Enumerable.Range(0, samples),
+            new ParallelOptions { MaxDegreeOfParallelism = Math.Min(64, Environment.ProcessorCount * 4) },
+            index =>
+            {
+                CreateJoinAttemptCommand attempt = attempts[index];
+                Stopwatch elapsed = Stopwatch.StartNew();
+                RequireSuccess(store.BindAttemptEndpoint(new(
+                    attempt.MediationHandle,
+                    AttemptPeerRole.Host,
+                    attempt.HostCapabilityFingerprint,
+                    PublicEndpoint(20_000 + index % 20_000),
+                    null)), "host punch");
+                RequireSuccess(store.BindAttemptEndpoint(new(
+                    attempt.MediationHandle,
+                    AttemptPeerRole.Client,
+                    attempt.ClientCapabilityFingerprint,
+                    PublicEndpoint(40_000 + index % 20_000),
+                    null)), "client punch");
+                RequireSuccess(store.ConsumeIntroduction(attempt.MediationHandle), "introduction");
+                latencies.Add(elapsed.Elapsed.TotalMilliseconds);
+            });
+        total.Stop();
+        return BuildMeasurement(
+            "simultaneous-punch-pairing",
+            latencies.ToArray(),
+            total.Elapsed,
+            budgetMilliseconds: 100,
+            minimumOperationsPerSecond: 2_000);
+    }
+
+    private static CapacityMeasurement Measure(
+        string operation,
+        int samples,
+        double budgetMilliseconds,
+        double minimumOperationsPerSecond,
+        Action<int> action)
+    {
+        double[] latencies = new double[samples];
+        Stopwatch total = Stopwatch.StartNew();
+        for (int index = 0; index < samples; index++)
+        {
+            long started = Stopwatch.GetTimestamp();
+            action(index);
+            latencies[index] = Stopwatch.GetElapsedTime(started).TotalMilliseconds;
+        }
+
+        total.Stop();
+        return BuildMeasurement(
+            operation,
+            latencies,
+            total.Elapsed,
+            budgetMilliseconds,
+            minimumOperationsPerSecond);
+    }
+
+    private static CapacityMeasurement BuildMeasurement(
+        string operation,
+        double[] latencies,
+        TimeSpan elapsed,
+        double budgetMilliseconds,
+        double minimumOperationsPerSecond)
+    {
+        Array.Sort(latencies);
+        double operationsPerSecond = latencies.Length / Math.Max(elapsed.TotalSeconds, 0.000_001);
+        double p95 = Percentile(latencies, 0.95);
+        return new(
+            operation,
+            latencies.Length,
+            Percentile(latencies, 0.50),
+            p95,
+            Percentile(latencies, 0.99),
+            operationsPerSecond,
+            minimumOperationsPerSecond,
+            budgetMilliseconds,
+            p95 <= budgetMilliseconds && operationsPerSecond >= minimumOperationsPerSecond);
+    }
+
+    private static double Percentile(double[] sorted, double percentile)
+    {
+        int index = Math.Clamp((int)Math.Ceiling(sorted.Length * percentile) - 1, 0, sorted.Length - 1);
+        return sorted[index];
+    }
+
+    private static SoakEvidence RunAcceleratedSoak(
+        CapacityOptions options,
+        List<string> failures)
+    {
+        GC.Collect();
+        GC.WaitForPendingFinalizers();
+        GC.Collect();
+        long managedBefore = GC.GetTotalMemory(forceFullCollection: true);
+        int handlesBefore = Process.GetCurrentProcess().HandleCount;
+        ManualClock clock = new();
+        CapacityOptions soakOptions = options with { Listings = 100, Attempts = 100 };
+        InMemoryEphemeralRendezvousStore store = CreateStore(soakOptions, clock);
+        Stopwatch elapsed = Stopwatch.StartNew();
+        int cycle = 0;
+        int peakScheduledExpiryEntries = 0;
+        while (cycle < options.SoakCycles
+               || elapsed.Elapsed < TimeSpan.FromSeconds(options.SoakSeconds))
+        {
+            StoredListing listing = CreateVisibleListing(store, cycle);
+            for (int refresh = 0; refresh < 10; refresh++)
+            {
+                clock.Advance(TimeSpan.FromTicks(1));
+                listing = RequireSuccess(store.RenewLease(new(
+                    listing.Definition.ListingId,
+                    listing.Definition.LeaseId,
+                    listing.Definition.LeaseFingerprint,
+                    listing.Definition.OwnerSubject,
+                    listing.Version)), "soak lease refresh");
+                listing = RequireSuccess(store.BindHostPresence(new(
+                    listing.Definition.HostPresenceHandle,
+                    listing.Definition.HostPresenceFingerprint,
+                    PublicEndpoint(10_000 + cycle % 50_000),
+                    null)), "soak presence refresh");
+            }
+
+            CreateJoinAttemptCommand attempt = CreateAttempt(cycle, listing);
+            RequireSuccess(store.CreateJoinAttempt(attempt), "soak join issuance");
+            RequireSuccess(store.ConsumeReplay(new("capacity-soak", $"replay-{cycle}")), "soak replay");
+            peakScheduledExpiryEntries = Math.Max(
+                peakScheduledExpiryEntries,
+                store.ScheduledExpiryEntryCount);
+            if (store.ScheduledExpiryEntryCount > 7)
+            {
+                failures.Add(
+                    $"Mutable deadline refresh grew the expiry queue to "
+                    + $"{store.ScheduledExpiryEntryCount} entries for one lifecycle.");
+                break;
+            }
+
+            clock.Advance(TimeSpan.FromSeconds(151));
+            EphemeralStoreSnapshot snapshot = store.GetSnapshot();
+            if (snapshot.ActiveListings != 0
+                || snapshot.ActiveJoinAttempts != 0
+                || snapshot.ReplayMarkers != 0
+                || snapshot.IdempotencyEntries != 0
+                || snapshot.RetainedOutcomeReports != 0)
+            {
+                failures.Add($"Accelerated soak retained state after cycle {cycle}.");
+                break;
+            }
+
+            cycle++;
+        }
+
+        elapsed.Stop();
+        GC.Collect();
+        GC.WaitForPendingFinalizers();
+        GC.Collect();
+        long managedGrowth = GC.GetTotalMemory(forceFullCollection: true) - managedBefore;
+        int handleGrowth = Process.GetCurrentProcess().HandleCount - handlesBefore;
+        if (managedGrowth > 67_108_864)
+        {
+            failures.Add($"Soak retained {managedGrowth} managed bytes; budget is 64 MiB.");
+        }
+
+        if (handleGrowth > 8)
+        {
+            failures.Add($"Soak retained {handleGrowth} process handles; budget is 8.");
+        }
+
+        return new(cycle, elapsed.Elapsed, peakScheduledExpiryEntries, managedGrowth, handleGrowth);
+    }
+
+    private static ObservedEndpoint PublicEndpoint(int port) =>
+        new(AddressFamilyKind.Ipv4, "203.0.113.10", port);
+
+    private static T RequireSuccess<T>(StoreResult<T> result, string operation)
+    {
+        if (!result.Succeeded)
+        {
+            throw new InvalidOperationException($"{operation} failed with {result.Code}.");
+        }
+
+        return result.Value!;
+    }
+
+    private static string ReadCpuModel()
+    {
+        const string cpuInfoPath = "/proc/cpuinfo";
+        if (!File.Exists(cpuInfoPath))
+        {
+            return "unavailable";
+        }
+
+        string? model = File.ReadLines(cpuInfoPath)
+            .FirstOrDefault(static line => line.StartsWith("model name", StringComparison.Ordinal));
+        int separator = model?.IndexOf(':') ?? -1;
+        return separator >= 0 ? model![(separator + 1)..].Trim() : "unavailable";
+    }
+
+    private static string ReadCgroupValue(string path) =>
+        File.Exists(path) ? File.ReadAllText(path).Trim() : "not-enforced";
+
+    private sealed class ManualClock : IWallClock, IMonotonicClock
+    {
+        public DateTimeOffset UtcNow { get; private set; } = DateTimeOffset.UtcNow;
+        public TimeSpan Elapsed { get; private set; }
+
+        public void Advance(TimeSpan duration)
+        {
+            UtcNow += duration;
+            Elapsed += duration;
+        }
+    }
+
+    private readonly record struct SoakEvidence(
+        int Cycles,
+        TimeSpan Duration,
+        int PeakScheduledExpiryEntries,
+        long ManagedGrowthBytes,
+        int HandleGrowth);
+}

tests/FinalFactory.Rendezvous.Capacity/FinalFactory.Rendezvous.Capacity.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <AssemblyName>FinalFactory.Rendezvous.Capacity</AssemblyName>
+    <RootNamespace>FinalFactory.Rendezvous.Capacity</RootNamespace>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="../../src/FinalFactory.Rendezvous.Contracts/FinalFactory.Rendezvous.Contracts.csproj" />
+    <ProjectReference Include="../../src/FinalFactory.Rendezvous.Server/FinalFactory.Rendezvous.Server.csproj" />
+  </ItemGroup>
+</Project>

tests/FinalFactory.Rendezvous.Capacity/Program.cs

@@ -0,0 +1,37 @@
+using System.Text.Json;
+
+namespace FinalFactory.Rendezvous.Capacity;
+
+internal static class Program
+{
+    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
+    {
+        WriteIndented = true,
+    };
+
+    public static async Task<int> Main(string[] args)
+    {
+        CapacityOptions options;
+        try
+        {
+            options = CapacityOptions.Parse(args);
+        }
+        catch (ArgumentException exception)
+        {
+            Console.Error.WriteLine(exception.Message);
+            return 2;
+        }
+
+        CapacityReport report = await CapacityRunner.RunAsync(options).ConfigureAwait(false);
+        string json = JsonSerializer.Serialize(report, JsonOptions);
+        Console.WriteLine(json);
+        if (options.OutputPath is not null)
+        {
+            string fullPath = Path.GetFullPath(options.OutputPath);
+            Directory.CreateDirectory(Path.GetDirectoryName(fullPath)!);
+            await File.WriteAllTextAsync(fullPath, json + Environment.NewLine).ConfigureAwait(false);
+        }
+
+        return report.Passed ? 0 : 1;
+    }
+}

tests/FinalFactory.Rendezvous.Capacity/packages.lock.json

@@ -0,0 +1,39 @@
+{
+  "version": 2,
+  "dependencies": {
+    "net10.0": {
+      "finalfactory.rendezvous.contracts": {
+        "type": "Project"
+      },
+      "finalfactory.rendezvous.server": {
+        "type": "Project",
+        "dependencies": {
+          "FinalFactory.Rendezvous.Contracts": "[1.0.0, )",
+          "LiteNetLib": "[2.1.4, )",
+          "Microsoft.AspNetCore.OpenApi": "[10.0.9, )"
+        }
+      },
+      "LiteNetLib": {
+        "type": "CentralTransitive",
+        "requested": "[2.1.4, )",
+        "resolved": "2.1.4",
+        "contentHash": "KWlxvMw3Urpqj9joD96LRiK+LC62pQNs/zkXRJc+rHnxgkGp+vV703xzDrxRmv+V1YhCFfIGzs5nrVWtREIlyA=="
+      },
+      "Microsoft.AspNetCore.OpenApi": {
+        "type": "CentralTransitive",
+        "requested": "[10.0.9, )",
+        "resolved": "10.0.9",
+        "contentHash": "1ihb8FO9cGgEK1/m3CTtT/SfnynwmiZib0W2pcDVj3KSWk/Sca4VOXEtaptKQc582zpFrzTFiwkGRCglt6H+WQ==",
+        "dependencies": {
+          "Microsoft.OpenApi": "2.0.0"
+        }
+      },
+      "Microsoft.OpenApi": {
+        "type": "CentralTransitive",
+        "requested": "[2.7.5, )",
+        "resolved": "2.7.5",
+        "contentHash": "0FA67RSnRM4tcBKqiqVu/HPdZ9+QOKbmeRjxRUGTCjPU4C0bmUhd97Dso7Yild5P7nOV6GxJ2xrK0Kv/O9xp0w=="
+      }
+    }
+  }
+}

tests/FinalFactory.Rendezvous.Tests/Client/RendezvousClientBehaviorTests.cs

@@ -102,6 +102,32 @@ public sealed class RendezvousClientBehaviorTests
         Assert.Equal(TimeSpan.FromMilliseconds(200), Assert.Single(delay.Delays));
     }
 
+    [Fact]
+    public async Task SilentServiceIsBoundedByTheConfiguredRequestTimeout()
+    {
+        using HttpClient httpClient = new(new SilentHandler())
+        {
+            BaseAddress = new("http://rendezvous.test/"),
+        };
+        RendezvousSessionBrowserClient browser = new(
+            httpClient,
+            new RendezvousClientOptions
+            {
+                MaximumSafeRetries = 0,
+                RequestTimeout = TimeSpan.FromMilliseconds(20),
+                JitterRatio = 0,
+            });
+
+        RendezvousClientResult<BrowseSessionsResponse> result = await browser.BrowseAsync(new()
+        {
+            GameId = new("space-game"),
+            EnvironmentId = new("production"),
+            ProtocolVersion = 7,
+        }).WaitAsync(TimeSpan.FromSeconds(2));
+
+        Assert.Equal(RendezvousErrorCode.ServiceUnavailable, result.Error);
+    }
+
     [Fact]
     public void SuccessResultRequiresAValue()
     {
@@ -339,4 +365,15 @@ public sealed class RendezvousClientBehaviorTests
             return Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
         }
     }
+
+    private sealed class SilentHandler : HttpMessageHandler
+    {
+        protected override async Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request,
+            CancellationToken cancellationToken)
+        {
+            await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
+            return new HttpResponseMessage(HttpStatusCode.OK);
+        }
+    }
 }

tests/FinalFactory.Rendezvous.Tests/Client/RendezvousClientIntegrationTests.cs

@@ -1,5 +1,9 @@
+using System.Diagnostics;
+using System.Net;
+using System.Net.Sockets;
 using FinalFactory.Rendezvous.Client;
 using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.Browser;
 using FinalFactory.Rendezvous.Server.Http;
 using FinalFactory.Rendezvous.Server.Provisioning;
@@ -18,6 +22,49 @@ namespace FinalFactory.Rendezvous.Tests.Client;
 
 public sealed class RendezvousClientIntegrationTests
 {
+    [Fact]
+    public async Task RestartReturnsTypedUnavailabilityThenAllowsHostReregistration()
+    {
+        int port = ReserveTcpPort();
+        string address = $"http://127.0.0.1:{port}";
+        using HttpClient client = new() { BaseAddress = new Uri(address) };
+        RendezvousClientOptions noRetry = new()
+        {
+            MaximumSafeRetries = 0,
+            RequestTimeout = TimeSpan.FromSeconds(1),
+        };
+        ClientTestHost first = await ClientTestHost.StartAsync(address);
+        RendezvousPublisherClient publisher = new(client, noRetry);
+        RendezvousClientResult<PublishedSession> registered = await publisher.RegisterAsync(
+            CreateRegistration(100),
+            first.PublisherCredential);
+        PublishedSession initialSession = AssertSuccess(registered);
+        BindPresence(first, initialSession, 41_100);
+        RendezvousSessionBrowserClient browser = new(client, noRetry);
+        BrowseSessionsResponse beforeRestart = AssertSuccess(await browser.BrowseAsync(BrowseRequest()));
+        Assert.Equal(initialSession.ListingId, Assert.Single(beforeRestart.Items).ListingId);
+        Stopwatch restart = Stopwatch.StartNew();
+        await first.DisposeAsync();
+
+        RendezvousClientResult<BrowseSessionsResponse> unavailable = await browser.BrowseAsync(BrowseRequest());
+        Assert.False(unavailable.IsSuccess);
+        Assert.Equal(RendezvousErrorCode.ServiceUnavailable, unavailable.Error);
+
+        await using ClientTestHost second = await ClientTestHost.StartAsync(address);
+        RendezvousClientResult<PublishedSession> reregistered = await publisher.RegisterAsync(
+            CreateRegistration(101),
+            second.PublisherCredential);
+        PublishedSession replacementSession = AssertSuccess(reregistered);
+        Assert.NotEqual(initialSession.ListingId, replacementSession.ListingId);
+        BindPresence(second, replacementSession, 41_101);
+        BrowseSessionsResponse afterRestart = AssertSuccess(await browser.BrowseAsync(BrowseRequest()));
+        Assert.Equal(replacementSession.ListingId, Assert.Single(afterRestart.Items).ListingId);
+        Assert.DoesNotContain(afterRestart.Items, item => item.ListingId == initialSession.ListingId);
+        Assert.True(
+            restart.Elapsed < TimeSpan.FromSeconds(5),
+            $"Local restart and host re-registration took {restart.Elapsed}.");
+    }
+
     [Fact]
     public async Task PublisherAndBrowserClientsCompleteTheRealSessionLifecycleAndPaging()
     {
@@ -101,6 +148,27 @@ public sealed class RendezvousClientIntegrationTests
         return Assert.IsAssignableFrom<T>(result.Value);
     }
 
+    private static void BindPresence(ClientTestHost host, PublishedSession session, int port)
+    {
+        Assert.True(host.Capabilities.TryFingerprint(
+            session.HostPresenceCapability,
+            out SecretFingerprint fingerprint));
+        Assert.Equal(StoreResultCode.Success, host.Store.BindHostPresence(new(
+            session.HostPresenceHandle,
+            fingerprint,
+            new(AddressFamilyKind.Ipv4, "203.0.113.80", port),
+            null)).Code);
+    }
+
+    private static BrowseSessionsRequest BrowseRequest() => new()
+    {
+        GameId = new("space-game"),
+        EnvironmentId = new("production"),
+        RegionId = new("eu-central"),
+        ProtocolVersion = 7,
+        PageSize = 10,
+    };
+
     private static RegisterSessionRequest CreateRegistration(int index) => new()
     {
         IdempotencyKey = $"sdk-integration-{index}",
@@ -138,7 +206,7 @@ public sealed class RendezvousClientIntegrationTests
         internal EphemeralCapabilityIssuer Capabilities { get; }
         internal string PublisherCredential { get; }
 
-        internal static async Task<ClientTestHost> StartAsync()
+        internal static async Task<ClientTestHost> StartAsync(string? bindAddress = null)
         {
             ManualRendezvousClock clock = new(ProvisioningTestData.Now);
             EphemeralStoreOptions stateOptions = new();
@@ -152,13 +220,15 @@ public sealed class RendezvousClientIntegrationTests
             string credential = provisioning.Credentials.Issue(principal, clock.UtcNow);
 
             WebApplicationBuilder builder = WebApplication.CreateBuilder();
-            builder.WebHost.UseUrls("http://127.0.0.1:0");
+            builder.WebHost.UseUrls(bindAddress ?? "http://127.0.0.1:0");
             builder.Services.ConfigureHttpJsonOptions(static options =>
                 ContractJson.Configure(options.SerializerOptions));
             builder.Services.Configure<RouteHandlerOptions>(static options =>
                 options.ThrowOnBadRequest = true);
             builder.Services.AddProblemDetails();
             builder.Services.AddExceptionHandler<RendezvousExceptionHandler>();
+            builder.Services.AddOptions<AbuseProtectionOptions>();
+            builder.Services.AddSingleton<AbuseProtectionService>();
             builder.Services.AddSingleton(provisioning);
             builder.Services.AddSingleton(provisioning.Credentials);
             builder.Services.AddSingleton(provisioning.PublisherAuthorization);
@@ -173,13 +243,14 @@ public sealed class RendezvousClientIntegrationTests
 
             WebApplication app = builder.Build();
             app.UseExceptionHandler();
+            app.UseMiddleware<HttpAbuseProtectionMiddleware>();
             app.MapRendezvousContractEndpoints();
             await app.StartAsync();
             IServer server = app.Services.GetRequiredService<IServer>();
-            string address = Assert.Single(server.Features.Get<IServerAddressesFeature>()!.Addresses);
+            string serviceAddress = Assert.Single(server.Features.Get<IServerAddressesFeature>()!.Addresses);
             return new(
                 app,
-                new HttpClient { BaseAddress = new Uri(address) },
+                new HttpClient { BaseAddress = new Uri(serviceAddress) },
                 store,
                 capabilities,
                 credential);
@@ -192,4 +263,13 @@ public sealed class RendezvousClientIntegrationTests
             await _application.DisposeAsync();
         }
     }
+
+    private static int ReserveTcpPort()
+    {
+        TcpListener listener = new(IPAddress.Loopback, 0);
+        listener.Start();
+        int port = ((IPEndPoint)listener.LocalEndpoint).Port;
+        listener.Stop();
+        return port;
+    }
 }

tests/FinalFactory.Rendezvous.Tests/Client/RendezvousCoordinatorBehaviorTests.cs

@@ -0,0 +1,885 @@
+using System.Net;
+using FinalFactory.Rendezvous.Client;
+using FinalFactory.Rendezvous.Contracts;
+using LiteNetLib;
+
+namespace FinalFactory.Rendezvous.Tests.Client;
+
+public sealed class RendezvousCoordinatorBehaviorTests
+{
+    [Fact]
+    public void LegacyCompletionConstructorsRemainCompatibleWithoutAllowingNonterminalStates()
+    {
+#pragma warning disable CS0618
+        RendezvousConnectionCompletedEventArgs client = new(
+            RendezvousConnectionState.Rejected,
+            (NetPeer?)null);
+        RendezvousHostAttemptCompletedEventArgs host = new(
+            new JoinAttemptId(Guid.NewGuid()),
+            RendezvousConnectionState.ManagerStopped,
+            (NetPeer?)null);
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+            new RendezvousConnectionCompletedEventArgs(
+                RendezvousConnectionState.Punching,
+                (NetPeer?)null));
+        Assert.Throws<ArgumentException>(() =>
+            new RendezvousHostAttemptCompletedEventArgs(
+                default,
+                RendezvousConnectionState.Rejected,
+                (NetPeer?)null));
+#pragma warning restore CS0618
+
+        Assert.Equal(ConnectionOutcomeKind.HostRejected, client.Outcome.Kind);
+        Assert.Equal(ConnectionOutcomeKind.ManagerStopped, host.Outcome.Kind);
+    }
+
+    [Theory]
+    [InlineData(RendezvousErrorCode.NotFound, ConnectionOutcomeKind.DirectoryNotFound, RendezvousConnectionFailureCategory.Directory)]
+    [InlineData(RendezvousErrorCode.Expired, ConnectionOutcomeKind.AttemptExpired, RendezvousConnectionFailureCategory.Authorization)]
+    [InlineData(RendezvousErrorCode.IncompatibleProtocol, ConnectionOutcomeKind.IncompatibleProtocol, RendezvousConnectionFailureCategory.Compatibility)]
+    [InlineData(RendezvousErrorCode.Forbidden, ConnectionOutcomeKind.Unauthorized, RendezvousConnectionFailureCategory.Authorization)]
+    [InlineData(RendezvousErrorCode.RateLimited, ConnectionOutcomeKind.RateLimited, RendezvousConnectionFailureCategory.Capacity)]
+    [InlineData(RendezvousErrorCode.StaleHost, ConnectionOutcomeKind.NoHostPresence, RendezvousConnectionFailureCategory.HostPresence)]
+    [InlineData(RendezvousErrorCode.ServiceUnavailable, ConnectionOutcomeKind.ServiceUnavailable, RendezvousConnectionFailureCategory.Service)]
+    public void AuthoritativeServiceErrorsMapToStableConnectionOutcomes(
+        RendezvousErrorCode error,
+        ConnectionOutcomeKind expectedKind,
+        RendezvousConnectionFailureCategory expectedCategory)
+    {
+        RendezvousConnectionOutcome outcome = RendezvousConnectionOutcome.FromServiceError(
+            error,
+            TimeSpan.FromMilliseconds(250));
+
+        Assert.Equal(expectedKind, outcome.Kind);
+        Assert.Equal(expectedCategory, outcome.Category);
+        Assert.Equal(RendezvousConnectionOutcomeSource.RendezvousService, outcome.Source);
+        Assert.Equal(error, outcome.ServiceError);
+    }
+
+    [Fact]
+    public void NatIntroductionAloneDoesNotCompleteTheClientAttempt()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness harness = new(clock);
+        int completions = 0;
+        harness.Coordinator.Completed += (_, _) => completions++;
+
+        ((INatPunchListener)harness.PunchEvents).OnNatIntroductionSuccess(
+            new IPEndPoint(IPAddress.Loopback, 65_000),
+            NatAddressType.External,
+            harness.IntroductionToken);
+
+        Assert.Equal(RendezvousConnectionState.Connecting, harness.Coordinator.State);
+        Assert.False(harness.Coordinator.IsCompleted);
+        Assert.Equal(0, completions);
+    }
+
+    [Fact]
+    public void ClientRejectsASyntacticallyValidIntroductionWithTheWrongTicket()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness harness = new(clock);
+        string forged = NatIntroductionTokenCodec.Encode(
+            harness.AttemptId,
+            Credential('F'));
+
+        ((INatPunchListener)harness.PunchEvents).OnNatIntroductionSuccess(
+            new IPEndPoint(IPAddress.Loopback, 65_000),
+            NatAddressType.External,
+            forged);
+
+        Assert.Equal(RendezvousConnectionState.Punching, harness.Coordinator.State);
+        Assert.False(harness.Coordinator.IsCompleted);
+    }
+
+    [Fact]
+    public void MediatorNetworkErrorProducesOneTypedTerminalOutcome()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness harness = new(clock);
+        int completions = 0;
+        harness.Coordinator.Completed += (_, _) => completions++;
+
+        harness.NetworkEvents.OnNetworkError(
+            new IPEndPoint(IPAddress.Loopback, 65_001),
+            System.Net.Sockets.SocketError.HostUnreachable);
+        RendezvousConnectionOutcome outcome = Assert.IsType<RendezvousConnectionOutcome>(
+            harness.Coordinator.Outcome);
+        harness.NetworkEvents.OnNetworkError(
+            new IPEndPoint(IPAddress.Loopback, 65_001),
+            System.Net.Sockets.SocketError.HostUnreachable);
+
+        Assert.Equal(ConnectionOutcomeKind.MediatorUnavailable, outcome.Kind);
+        Assert.Equal(RendezvousConnectionFailureCategory.Mediation, outcome.Category);
+        Assert.Equal(1, completions);
+        Assert.Same(outcome, harness.Coordinator.Outcome);
+    }
+
+    [Fact]
+    public void CancellationCompletesExactlyOnceAndLateCallbacksCannotReopenTheAttempt()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness harness = new(clock);
+        List<RendezvousConnectionState> completions = [];
+        harness.Coordinator.Completed += (_, completion) => completions.Add(completion.State);
+
+        harness.Coordinator.Cancel();
+        harness.Coordinator.Poll();
+        ((INatPunchListener)harness.PunchEvents).OnNatIntroductionSuccess(
+            new IPEndPoint(IPAddress.Loopback, 65_000),
+            NatAddressType.External,
+            harness.IntroductionToken);
+        harness.Coordinator.Poll();
+
+        Assert.Equal(RendezvousConnectionState.Cancelled, harness.Coordinator.State);
+        Assert.Equal([RendezvousConnectionState.Cancelled], completions);
+        Assert.Equal(ConnectionOutcomeKind.Cancelled, harness.Coordinator.Outcome!.Kind);
+    }
+
+    [Fact]
+    public void ExhaustedPunchBudgetTimesOutExactlyOnceUnderAFakeClock()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness harness = new(clock, new RendezvousCoordinatorOptions
+        {
+            MaximumPunchRequests = 1,
+            InitialPunchRetryDelay = TimeSpan.FromMilliseconds(10),
+            MaximumPunchRetryDelay = TimeSpan.FromMilliseconds(10),
+            JitterRatio = 0,
+        });
+        int completions = 0;
+        harness.Coordinator.Completed += (_, _) => completions++;
+
+        harness.Coordinator.Poll();
+        clock.Advance(TimeSpan.FromMilliseconds(10));
+        harness.Coordinator.Poll();
+        clock.Advance(TimeSpan.FromMinutes(1));
+        harness.Coordinator.Poll();
+
+        Assert.Equal(RendezvousConnectionState.TimedOut, harness.Coordinator.State);
+        Assert.Equal(1, completions);
+        Assert.Equal(ConnectionOutcomeKind.PunchTimedOut, harness.Coordinator.Outcome!.Kind);
+        Assert.Equal(
+            RendezvousConnectionFailureCategory.NatTraversal,
+            harness.Coordinator.Outcome.Category);
+    }
+
+    [Fact]
+    public void WallClockRollbackCannotExtendTheMonotonicPunchDeadline()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness harness = new(clock, new RendezvousCoordinatorOptions
+        {
+            PunchTimeout = TimeSpan.FromSeconds(10),
+            JitterRatio = 0,
+        });
+        clock.AdjustWallClock(TimeSpan.FromHours(-1));
+        clock.Advance(TimeSpan.FromSeconds(11));
+
+        harness.Coordinator.Poll();
+
+        Assert.Equal(ConnectionOutcomeKind.PunchTimedOut, harness.Coordinator.Outcome!.Kind);
+        Assert.Equal(TimeSpan.FromSeconds(11), harness.Coordinator.Outcome.Elapsed);
+    }
+
+    [Fact]
+    public void DirectConnectTimeoutOffersFallbackWithoutConnectingIt()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        NetworkEndpoint fallback = new()
+        {
+            AddressFamily = AddressFamilyKind.Ipv4,
+            Address = "203.0.113.90",
+            Port = 9_060,
+        };
+        using ClientHarness harness = new(clock, new RendezvousCoordinatorOptions
+        {
+            DirectConnectTimeout = TimeSpan.FromMilliseconds(10),
+            DedicatedFallbackOverride = fallback,
+            JitterRatio = 0,
+        });
+        ((INatPunchListener)harness.PunchEvents).OnNatIntroductionSuccess(
+            new IPEndPoint(IPAddress.Loopback, 65_000),
+            NatAddressType.External,
+            harness.IntroductionToken);
+        clock.Advance(TimeSpan.FromMilliseconds(10));
+
+        harness.Coordinator.Poll();
+
+        RendezvousConnectionOutcome outcome = Assert.IsType<RendezvousConnectionOutcome>(
+            harness.Coordinator.Outcome);
+        Assert.Equal(ConnectionOutcomeKind.DirectConnectTimedOut, outcome.Kind);
+        Assert.Equal(RendezvousConnectionPhase.DirectConnection, outcome.Phase);
+        Assert.Equal("203.0.113.90", outcome.DedicatedFallback!.Address);
+        List<NetPeer> connectedPeers = [];
+        harness.Manager.GetConnectedPeers(connectedPeers);
+        Assert.Empty(connectedPeers);
+
+        ((INatPunchListener)harness.PunchEvents).OnNatIntroductionSuccess(
+            new IPEndPoint(IPAddress.Loopback, 65_001),
+            NatAddressType.External,
+            harness.IntroductionToken);
+        Assert.Same(outcome, harness.Coordinator.Outcome);
+    }
+
+    [Fact]
+    public void ManagerShutdownAndDisposalEachReleaseTheirTerminalPathOnce()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness stopped = new(clock);
+        int stoppedCompletions = 0;
+        stopped.Coordinator.Completed += (_, _) => stoppedCompletions++;
+        stopped.Manager.Stop();
+
+        stopped.Coordinator.Poll();
+        stopped.Coordinator.Poll();
+
+        Assert.Equal(RendezvousConnectionState.ManagerStopped, stopped.Coordinator.State);
+        Assert.Equal(1, stoppedCompletions);
+
+        using ClientHarness disposed = new(clock);
+        int disposedCompletions = 0;
+        disposed.Coordinator.Completed += (_, _) => disposedCompletions++;
+        disposed.Coordinator.Dispose();
+        disposed.Coordinator.Dispose();
+        ((INatPunchListener)disposed.PunchEvents).OnNatIntroductionSuccess(
+            new IPEndPoint(IPAddress.Loopback, 65_000),
+            NatAddressType.External,
+            disposed.IntroductionToken);
+
+        Assert.Equal(RendezvousConnectionState.Disposed, disposed.Coordinator.State);
+        Assert.Equal(1, disposedCompletions);
+        Assert.Throws<ObjectDisposedException>(() => disposed.Coordinator.Poll());
+    }
+
+    [Fact]
+    public async Task DirectConnectionRejectionProducesOneTerminalTransition()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        using ClientHarness client = new(clock);
+        EventBasedNetListener rejectingEvents = new();
+        rejectingEvents.ConnectionRequestEvent += request => request.Reject();
+        NetManager rejectingHost = new(rejectingEvents);
+        try
+        {
+            Assert.True(rejectingHost.Start(0));
+            int completions = 0;
+            client.Coordinator.Completed += (_, _) => completions++;
+            ((INatPunchListener)client.PunchEvents).OnNatIntroductionSuccess(
+                new IPEndPoint(IPAddress.Loopback, rejectingHost.LocalPort),
+                NatAddressType.External,
+                client.IntroductionToken);
+
+            DateTime deadline = DateTime.UtcNow.AddSeconds(2);
+            while (!client.Coordinator.IsCompleted && DateTime.UtcNow < deadline)
+            {
+                rejectingHost.PollEvents();
+                client.Coordinator.Poll();
+                await Task.Delay(2);
+            }
+
+            Assert.Equal(RendezvousConnectionState.Rejected, client.Coordinator.State);
+            Assert.Equal(1, completions);
+            Assert.Equal(ConnectionOutcomeKind.HostRejected, client.Coordinator.Outcome!.Kind);
+            Assert.Equal(
+                RendezvousConnectionOutcomeSource.RemoteHost,
+                client.Coordinator.Outcome.Source);
+            client.Coordinator.Poll();
+            Assert.Equal(1, completions);
+        }
+        finally
+        {
+            rejectingHost.Stop();
+        }
+    }
+
+    [Fact]
+    public void UnsynchronizedLiteNetCallbacksAreRejectedAtConstruction()
+    {
+        RendezvousNetListener networkEvents = new();
+        NetManager manager = networkEvents.CreateManager();
+        manager.UnsyncedEvents = true;
+        try
+        {
+            Assert.True(manager.Start(0));
+            Assert.Throws<InvalidOperationException>(() => new RendezvousClientCoordinator(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 9_050),
+                CreateAttempt(new DateTimeOffset(2030, 1, 1, 0, 0, 30, TimeSpan.Zero))));
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public void CoordinatorRejectsAManagerCreatedByAnotherRoutingListener()
+    {
+        RendezvousNetListener managerEvents = new();
+        NetManager manager = managerEvents.CreateManager();
+        RendezvousNetListener mismatchedEvents = new();
+        try
+        {
+            Assert.True(manager.Start(0));
+
+            Assert.Throws<InvalidOperationException>(() => new RendezvousClientCoordinator(
+                manager,
+                mismatchedEvents,
+                new IPEndPoint(IPAddress.Loopback, 9_050),
+                CreateAttempt(new DateTimeOffset(2030, 1, 1, 0, 0, 30, TimeSpan.Zero))));
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task PublishedSessionTimingRemainsValidDuringConcurrentRenewalReads()
+    {
+        DateTimeOffset firstExpiry = new(2030, 1, 1, 0, 1, 0, TimeSpan.Zero);
+        DateTimeOffset secondExpiry = new(2030, 1, 1, 0, 2, 0, TimeSpan.Zero);
+        PublishedSession session = CreateSession(firstExpiry);
+
+        Task writer = Task.Run(() =>
+        {
+            for (int index = 0; index < 10_000; index++)
+            {
+                session.ExpiresAt = index % 2 == 0 ? firstExpiry : secondExpiry;
+                session.LeaseRenewAfterSeconds = index % 2 == 0 ? 10 : 20;
+            }
+        });
+        Task reader = Task.Run(() =>
+        {
+            for (int index = 0; index < 10_000; index++)
+            {
+                DateTimeOffset expiry = session.ExpiresAt;
+                int renewAfter = session.LeaseRenewAfterSeconds;
+                Assert.True(expiry == firstExpiry || expiry == secondExpiry);
+                Assert.True(renewAfter is 10 or 20 or 30);
+            }
+        });
+
+        await Task.WhenAll(writer, reader);
+    }
+
+    [Fact]
+    public async Task HostDoesNotMistakeAnIntroducedAttemptForCancellationWhenItLeavesPolling()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        EventBasedNatPunchListener punchEvents = networkEvents.PunchEvents;
+        NetManager manager = networkEvents.CreateManager();
+        JoinAttemptId attemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000111"));
+        HostJoinAttempt invitation = new()
+        {
+            AttemptId = attemptId,
+            MediationHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000112")),
+            HostPunchCapability = Credential('H'),
+            ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
+                NatIntroductionTokenCodec.Encode(attemptId, Credential('T'))),
+            ExpiresAt = clock.UtcNow + TimeSpan.FromSeconds(30),
+        };
+        MutableJoinClient joins = new([invitation]);
+        using ConnectionTicketValidator tickets = new(16, clock);
+        try
+        {
+            Assert.True(manager.Start(0));
+            using RendezvousHostCoordinator host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions { JitterRatio = 0 },
+                clock,
+                tickets);
+            int completions = 0;
+            host.AttemptCompleted += (_, _) => completions++;
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            Assert.Equal(1, host.PendingAttemptCount);
+
+            ((INatPunchListener)punchEvents).OnNatIntroductionSuccess(
+                new IPEndPoint(IPAddress.Loopback, 65_003),
+                NatAddressType.External,
+                NatIntroductionTokenCodec.Encode(attemptId, Credential('T')));
+            joins.Attempts = [];
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+
+            Assert.Equal(1, host.PendingAttemptCount);
+            Assert.Equal(0, completions);
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task HostCancellationSnapshotRevokesAnAuthorizedTicketAndCompletesOnce()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        EventBasedNatPunchListener punchEvents = networkEvents.PunchEvents;
+        NetManager manager = networkEvents.CreateManager();
+        JoinAttemptId attemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000131"));
+        string ticket = NatIntroductionTokenCodec.Encode(attemptId, Credential('T'));
+        HostJoinAttempt invitation = CreateHostAttempt(
+            attemptId,
+            new(Guid.Parse("00000000-0000-0000-0000-000000000132")),
+            ticket,
+            clock.UtcNow + TimeSpan.FromSeconds(30));
+        MutableJoinClient joins = new([invitation]);
+        using ConnectionTicketValidator tickets = new(16, clock);
+        try
+        {
+            Assert.True(manager.Start(0));
+            using RendezvousHostCoordinator host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions { JitterRatio = 0 },
+                clock,
+                tickets);
+            List<RendezvousConnectionState> completions = [];
+            host.AttemptCompleted += (_, completion) => completions.Add(completion.State);
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            ((INatPunchListener)punchEvents).OnNatIntroductionSuccess(
+                new IPEndPoint(IPAddress.Loopback, 65_003),
+                NatAddressType.External,
+                ticket);
+
+            invitation.IsCancelled = true;
+            joins.Attempts = [invitation];
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            host.Poll();
+
+            Assert.Equal(0, host.PendingAttemptCount);
+            Assert.Equal([RendezvousConnectionState.Cancelled], completions);
+            Assert.Equal(
+                ConnectionTicketConsumptionResult.Revoked,
+                tickets.Consume(attemptId, ticket));
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task HostAppliesOnlyTheLatestUnpolledSnapshot()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        NetManager manager = networkEvents.CreateManager();
+        JoinAttemptId attemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000141"));
+        HostJoinAttempt invitation = CreateHostAttempt(
+            attemptId,
+            new(Guid.Parse("00000000-0000-0000-0000-000000000142")),
+            NatIntroductionTokenCodec.Encode(attemptId, Credential('T')),
+            clock.UtcNow + TimeSpan.FromSeconds(30));
+        MutableJoinClient joins = new([invitation]);
+        try
+        {
+            Assert.True(manager.Start(0));
+            using RendezvousHostCoordinator host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions { JitterRatio = 0 },
+                clock,
+                null);
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            joins.Attempts = [];
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+
+            host.Poll();
+
+            Assert.Equal(0, host.PendingAttemptCount);
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task DisposingHostDuringRefreshDropsTheLateSnapshot()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        NetManager manager = networkEvents.CreateManager();
+        BlockingJoinClient joins = new();
+        try
+        {
+            Assert.True(manager.Start(0));
+            RendezvousHostCoordinator host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions { JitterRatio = 0 },
+                clock,
+                null);
+            Task<RendezvousClientResult<int>> refresh = host.RefreshJoinAttemptsAsync();
+            await joins.WaitUntilCalled;
+
+            host.Dispose();
+            joins.Complete([]);
+
+            await Assert.ThrowsAsync<ObjectDisposedException>(async () => await refresh);
+            Assert.Throws<ObjectDisposedException>(() => host.Poll());
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task HostDeadlinesAreNotDelayedByTheBoundedRetryQueue()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        NetManager manager = networkEvents.CreateManager();
+        JoinAttemptId firstId = new(Guid.Parse("00000000-0000-0000-0000-000000000151"));
+        JoinAttemptId secondId = new(Guid.Parse("00000000-0000-0000-0000-000000000152"));
+        DateTimeOffset expiresAt = clock.UtcNow + TimeSpan.FromSeconds(1);
+        MutableJoinClient joins = new([
+            CreateHostAttempt(
+                firstId,
+                new(Guid.Parse("00000000-0000-0000-0000-000000000153")),
+                NatIntroductionTokenCodec.Encode(firstId, Credential('T')),
+                expiresAt),
+            CreateHostAttempt(
+                secondId,
+                new(Guid.Parse("00000000-0000-0000-0000-000000000154")),
+                NatIntroductionTokenCodec.Encode(secondId, Credential('U')),
+                expiresAt),
+        ]);
+        try
+        {
+            Assert.True(manager.Start(0));
+            using RendezvousHostCoordinator host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions
+                {
+                    MaximumAttemptChecksPerPoll = 1,
+                    JitterRatio = 0,
+                },
+                clock,
+                null);
+            List<RendezvousConnectionState> completions = [];
+            host.AttemptCompleted += (_, completion) => completions.Add(completion.State);
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            clock.Advance(TimeSpan.FromSeconds(2));
+
+            host.Poll();
+
+            Assert.Equal(0, host.PendingAttemptCount);
+            Assert.Equal(
+                [RendezvousConnectionState.TimedOut, RendezvousConnectionState.TimedOut],
+                completions);
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task HostStopPublishesEveryCompletionBeforeReentrantDisposalCanTearDownState()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        NetManager manager = networkEvents.CreateManager();
+        JoinAttemptId firstId = new(Guid.Parse("00000000-0000-0000-0000-000000000161"));
+        JoinAttemptId secondId = new(Guid.Parse("00000000-0000-0000-0000-000000000162"));
+        MutableJoinClient joins = new([
+            CreateHostAttempt(
+                firstId,
+                new(Guid.Parse("00000000-0000-0000-0000-000000000163")),
+                NatIntroductionTokenCodec.Encode(firstId, Credential('T')),
+                clock.UtcNow + TimeSpan.FromSeconds(30)),
+            CreateHostAttempt(
+                secondId,
+                new(Guid.Parse("00000000-0000-0000-0000-000000000164")),
+                NatIntroductionTokenCodec.Encode(secondId, Credential('U')),
+                clock.UtcNow + TimeSpan.FromSeconds(30)),
+        ]);
+        RendezvousHostCoordinator? host = null;
+        try
+        {
+            Assert.True(manager.Start(0));
+            host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions { JitterRatio = 0 },
+                clock,
+                null);
+            int completions = 0;
+            host.AttemptCompleted += (_, _) =>
+            {
+                completions++;
+                if (completions == 1)
+                {
+                    host.Dispose();
+                }
+            };
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            manager.Stop();
+
+            host.Poll();
+
+            Assert.Equal(2, completions);
+            Assert.Equal(0, host.PendingAttemptCount);
+        }
+        finally
+        {
+            host?.Dispose();
+            manager.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task HostPunchTimeoutUsesItsOwnFakeClockBudget()
+    {
+        ManualCoordinatorClock clock = new(new(2030, 1, 1, 0, 0, 0, TimeSpan.Zero));
+        RendezvousNetListener networkEvents = new();
+        NetManager manager = networkEvents.CreateManager();
+        JoinAttemptId attemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000161"));
+        MutableJoinClient joins = new([
+            CreateHostAttempt(
+                attemptId,
+                new(Guid.Parse("00000000-0000-0000-0000-000000000162")),
+                NatIntroductionTokenCodec.Encode(attemptId, Credential('T')),
+                clock.UtcNow + TimeSpan.FromSeconds(30)),
+        ]);
+        try
+        {
+            Assert.True(manager.Start(0));
+            using RendezvousHostCoordinator host = new(
+                manager,
+                networkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_002),
+                CreateSession(clock.UtcNow + TimeSpan.FromMinutes(1)),
+                joins,
+                new RendezvousCoordinatorOptions
+                {
+                    MaximumPunchRequests = 20,
+                    PunchTimeout = TimeSpan.FromMilliseconds(10),
+                    JitterRatio = 0,
+                },
+                clock,
+                null);
+            RendezvousHostAttemptCompletedEventArgs? completion = null;
+            host.AttemptCompleted += (_, value) => completion = value;
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            clock.Advance(TimeSpan.FromMilliseconds(10));
+
+            host.Poll();
+
+            Assert.Equal(ConnectionOutcomeKind.PunchTimedOut, completion!.Outcome.Kind);
+            Assert.Equal(TimeSpan.FromMilliseconds(10), completion.Outcome.Elapsed);
+        }
+        finally
+        {
+            manager.Stop();
+        }
+    }
+
+    private static CreateJoinAttemptResponse CreateAttempt(DateTimeOffset expiresAt) => new()
+    {
+        AttemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000101")),
+        MediationHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000102")),
+        ClientPunchCapability = Credential('C'),
+        ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
+            NatIntroductionTokenCodec.Encode(
+                new JoinAttemptId(Guid.Parse("00000000-0000-0000-0000-000000000101")),
+                Credential('T'))),
+        ExpiresAt = expiresAt,
+    };
+
+    private static PublishedSession CreateSession(DateTimeOffset expiresAt) => new(new RegisterSessionResponse
+    {
+        ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000121")),
+        LeaseId = new(Guid.Parse("00000000-0000-0000-0000-000000000122")),
+        LeaseToken = "lease-token",
+        HostPresenceHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000123")),
+        HostPresenceCapability = Credential('P'),
+        ExpiresAt = expiresAt,
+        LeaseRenewAfterSeconds = 30,
+        HostPresenceRefreshAfterSeconds = 10,
+    });
+
+    private static HostJoinAttempt CreateHostAttempt(
+        JoinAttemptId attemptId,
+        MediationHandle mediationHandle,
+        string connectionTicket,
+        DateTimeOffset expiresAt) => new()
+        {
+            AttemptId = attemptId,
+            MediationHandle = mediationHandle,
+            HostPunchCapability = Credential('H'),
+            ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(connectionTicket),
+            ExpiresAt = expiresAt,
+        };
+
+    private static string Credential(char value) => new(value, ContractLimits.DerivedCredentialCharacters);
+
+    private sealed class ClientHarness : IDisposable
+    {
+        internal ClientHarness(
+            ManualCoordinatorClock clock,
+            RendezvousCoordinatorOptions? options = null)
+        {
+            NetworkEvents = new();
+            PunchEvents = NetworkEvents.PunchEvents;
+            Manager = NetworkEvents.CreateManager();
+            Assert.True(Manager.Start(0));
+            CreateJoinAttemptResponse attempt = CreateAttempt(clock.UtcNow + TimeSpan.FromSeconds(30));
+            AttemptId = attempt.AttemptId;
+            IntroductionToken = NatIntroductionTokenCodec.Encode(
+                attempt.AttemptId,
+                Credential('T'));
+            Coordinator = new(
+                Manager,
+                NetworkEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_001),
+                attempt,
+                options,
+                clock);
+        }
+
+        internal RendezvousNetListener NetworkEvents { get; }
+        internal EventBasedNatPunchListener PunchEvents { get; }
+        internal NetManager Manager { get; }
+        internal RendezvousClientCoordinator Coordinator { get; }
+        internal JoinAttemptId AttemptId { get; }
+        internal string IntroductionToken { get; }
+
+        public void Dispose()
+        {
+            Coordinator.Dispose();
+            Manager.Stop();
+        }
+    }
+
+    private sealed class MutableJoinClient(IReadOnlyList<HostJoinAttempt> attempts) : IRendezvousJoinClient
+    {
+        internal IReadOnlyList<HostJoinAttempt> Attempts { get; set; } = attempts;
+
+        public Task<RendezvousConnectionStartResult> CreateConnectionAttemptAsync(
+            CreateJoinAttemptRequest request,
+            NetworkEndpoint? dedicatedFallback = null,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
+            CreateJoinAttemptRequest request,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<bool>> CancelAsync(
+            CreateJoinAttemptResponse attempt,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
+            PublishedSession session,
+            int pageSize = ContractLimits.BrowserPageMaxItems,
+            string? cursor = null,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
+            PublishedSession session,
+            int maximumPages = 100,
+            CancellationToken cancellationToken = default) => Task.FromResult(
+                RendezvousClientResult.Success(Attempts));
+
+        public Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
+            CreateJoinAttemptResponse attempt,
+            RendezvousConnectionOutcome outcome,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+    }
+
+    private sealed class BlockingJoinClient : IRendezvousJoinClient
+    {
+        private readonly TaskCompletionSource<bool> _called = new(
+            TaskCreationOptions.RunContinuationsAsynchronously);
+        private readonly TaskCompletionSource<IReadOnlyList<HostJoinAttempt>> _result = new(
+            TaskCreationOptions.RunContinuationsAsynchronously);
+
+        internal Task WaitUntilCalled => _called.Task;
+
+        internal void Complete(IReadOnlyList<HostJoinAttempt> attempts) =>
+            _result.SetResult(attempts);
+
+        public Task<RendezvousConnectionStartResult> CreateConnectionAttemptAsync(
+            CreateJoinAttemptRequest request,
+            NetworkEndpoint? dedicatedFallback = null,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
+            CreateJoinAttemptRequest request,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<bool>> CancelAsync(
+            CreateJoinAttemptResponse attempt,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
+            PublishedSession session,
+            int pageSize = ContractLimits.BrowserPageMaxItems,
+            string? cursor = null,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public async Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
+            PublishedSession session,
+            int maximumPages = 100,
+            CancellationToken cancellationToken = default)
+        {
+            _called.SetResult(true);
+            return RendezvousClientResult.Success(await _result.Task.WaitAsync(cancellationToken));
+        }
+
+        public Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
+            CreateJoinAttemptResponse attempt,
+            RendezvousConnectionOutcome outcome,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+    }
+
+    private sealed class ManualCoordinatorClock(DateTimeOffset now) :
+        IRendezvousCoordinatorClock,
+        IConnectionTicketClock
+    {
+        public DateTimeOffset UtcNow { get; private set; } = now;
+        public TimeSpan Elapsed { get; private set; }
+
+        internal void Advance(TimeSpan amount)
+        {
+            UtcNow += amount;
+            Elapsed += amount;
+        }
+
+        internal void AdjustWallClock(TimeSpan amount) => UtcNow += amount;
+    }
+}

tests/FinalFactory.Rendezvous.Tests/Client/RendezvousCoordinatorIntegrationTests.cs

@@ -0,0 +1,283 @@
+using System.Net;
+using FinalFactory.Rendezvous.Client;
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.JoinAttempts;
+using FinalFactory.Rendezvous.Server.State;
+using FinalFactory.Rendezvous.Server.Transport;
+using FinalFactory.Rendezvous.Tests.JoinAttempts;
+using LiteNetLib;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+
+namespace FinalFactory.Rendezvous.Tests.Client;
+
+public sealed class RendezvousCoordinatorIntegrationTests
+{
+    [Fact]
+    public async Task CallerOwnedManagersCompleteAuthenticatedDirectConnectionAndRejectTicketReplay()
+    {
+        using CancellationTokenSource timeout = new(TimeSpan.FromSeconds(8));
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse created = fixture.Create(registration.ListingId, "sdk-direct-connect");
+        HostJoinAttempt hostAttempt = fixture.Service.BrowseForHost(
+            registration.ListingId,
+            ContractLimits.ContractVersion,
+            registration.LeaseToken,
+            ContractLimits.BrowserPageMaxItems,
+            null).Value!.Items.Single(item => item.AttemptId == created.AttemptId);
+        NatMediationProcessor processor = new(
+            fixture.Sessions.Store,
+            fixture.Sessions.Capabilities,
+            fixture.Service);
+        using UdpMediatorService mediatorService = new(
+            Options.Create(new UdpMediatorOptions
+            {
+                ListenAddress = IPAddress.Loopback.ToString(),
+                Port = 0,
+                PollIntervalMilliseconds = 1,
+            }),
+            NullLogger<UdpMediatorService>.Instance,
+            processor);
+        await mediatorService.StartAsync(timeout.Token);
+
+        RendezvousNetListener hostEvents = new();
+        RendezvousNetListener clientEvents = new();
+        bool gameplayConnectionRequestHandled = false;
+        hostEvents.GameplayEvents.ConnectionRequestEvent += _ =>
+            gameplayConnectionRequestHandled = true;
+        EventBasedNatPunchListener hostPunch = hostEvents.PunchEvents;
+        EventBasedNatPunchListener clientPunch = clientEvents.PunchEvents;
+        NetManager hostManager = hostEvents.CreateManager();
+        NetManager clientManager = clientEvents.CreateManager();
+        string? introductionToken = null;
+        string? hostIntroductionToken = null;
+        clientPunch.NatIntroductionSuccess += (_, _, token) => introductionToken = token;
+        hostPunch.NatIntroductionSuccess += (_, _, token) => hostIntroductionToken = token;
+
+        try
+        {
+            Assert.True(hostManager.Start(0));
+            Assert.True(clientManager.Start(0));
+            IPEndPoint mediator = Assert.IsType<IPEndPoint>(mediatorService.LocalEndpoint);
+            FakeJoinClient joinClient = new([hostAttempt]);
+            FixedCoordinatorClock clock = new(fixture.Sessions.Clock.UtcNow);
+            using ConnectionTicketValidator tickets = new(1_024, clock);
+            using RendezvousHostCoordinator host = new(
+                hostManager,
+                hostEvents,
+                mediator,
+                new PublishedSession(registration),
+                joinClient,
+                FastOptions(),
+                clock,
+                tickets);
+            using RendezvousClientCoordinator client = new(
+                clientManager,
+                clientEvents,
+                mediator,
+                created,
+                FastOptions(),
+                clock);
+            List<RendezvousHostAttemptCompletedEventArgs> hostCompletions = [];
+            List<RendezvousConnectionCompletedEventArgs> clientCompletions = [];
+            host.AttemptCompleted += (_, completion) => hostCompletions.Add(completion);
+            client.Completed += (_, completion) => clientCompletions.Add(completion);
+            Assert.True((await host.RefreshJoinAttemptsAsync(timeout.Token)).IsSuccess);
+
+            while ((!client.IsCompleted || hostCompletions.Count == 0)
+                   && !timeout.IsCancellationRequested)
+            {
+                host.Poll();
+                client.Poll();
+                await Task.Delay(2);
+            }
+
+            Assert.True(
+                client.State == RendezvousConnectionState.Connected,
+                $"Client ended in {client.State}; host pending={host.PendingAttemptCount}; "
+                + $"host completions={hostCompletions.Count}; introduction={introductionToken is not null}; "
+                + $"host introduction={hostIntroductionToken is not null}; "
+                + $"client digest={NatIntroductionTokenCodec.MatchesDigest(introductionToken, created.ConnectionTicketDigest)}; "
+                + $"host digest={NatIntroductionTokenCodec.MatchesDigest(hostIntroductionToken, hostAttempt.ConnectionTicketDigest)}.");
+            Assert.NotNull(client.ConnectedPeer);
+            Assert.Equal(
+                RendezvousConnectionState.Connected,
+                Assert.Single(clientCompletions).State);
+            RendezvousHostAttemptCompletedEventArgs hostCompletion = Assert.Single(hostCompletions);
+            Assert.Equal(created.AttemptId, hostCompletion.AttemptId);
+            Assert.Equal(RendezvousConnectionState.Connected, hostCompletion.State);
+            Assert.NotNull(hostCompletion.Peer);
+            Assert.False(gameplayConnectionRequestHandled);
+            Assert.True(NatIntroductionTokenCodec.TryDecode(
+                introductionToken,
+                out NatIntroductionToken? introduction));
+            Assert.NotNull(introduction);
+
+            EventBasedNetListener replayEvents = new();
+            bool replayConnected = false;
+            replayEvents.PeerConnectedEvent += _ => replayConnected = true;
+            NetManager replayManager = new(replayEvents);
+            try
+            {
+                Assert.True(replayManager.Start(0));
+                replayManager.Connect(
+                    new IPEndPoint(IPAddress.Loopback, hostManager.LocalPort),
+                    DirectConnectionRequestCodec.Encode(
+                        created.AttemptId,
+                        introduction.ConnectionTicket));
+                DateTime replayDeadline = DateTime.UtcNow.AddSeconds(1);
+                while (DateTime.UtcNow < replayDeadline && !replayConnected)
+                {
+                    host.Poll();
+                    replayManager.PollEvents();
+                    await Task.Delay(2, timeout.Token);
+                }
+
+                Assert.False(replayConnected);
+                Assert.False(gameplayConnectionRequestHandled);
+                Assert.Single(hostCompletions);
+            }
+            finally
+            {
+                replayManager.Stop();
+            }
+        }
+        finally
+        {
+            hostManager.Stop();
+            clientManager.Stop();
+            await mediatorService.StopAsync(CancellationToken.None);
+        }
+    }
+
+    [Fact]
+    public async Task HostDefersADirectRequestUntilTheMatchingNatIntroductionArrives()
+    {
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse created = fixture.Create(registration.ListingId, "direct-before-nat");
+        HostJoinAttempt hostAttempt = fixture.Service.BrowseForHost(
+            registration.ListingId,
+            ContractLimits.ContractVersion,
+            registration.LeaseToken,
+            ContractLimits.BrowserPageMaxItems,
+            null).Value!.Items.Single(item => item.AttemptId == created.AttemptId);
+        IntroductionEndpoints introduction = fixture.Introduce(registration, created);
+        ConnectionTicketGrant grant = Assert.IsType<ConnectionTicketGrant>(
+            fixture.Service.IssueConnectionTicket(introduction.Attempt).Value);
+        RendezvousNetListener hostEvents = new();
+        EventBasedNatPunchListener hostPunch = hostEvents.PunchEvents;
+        EventBasedNetListener clientEvents = new();
+        bool clientConnected = false;
+        clientEvents.PeerConnectedEvent += _ => clientConnected = true;
+        NetManager hostManager = hostEvents.CreateManager();
+        NetManager clientManager = new(clientEvents);
+        try
+        {
+            Assert.True(hostManager.Start(0));
+            Assert.True(clientManager.Start(0));
+            FixedCoordinatorClock clock = new(fixture.Sessions.Clock.UtcNow);
+            FakeJoinClient joins = new([hostAttempt]);
+            using ConnectionTicketValidator tickets = new(16, clock);
+            using RendezvousHostCoordinator host = new(
+                hostManager,
+                hostEvents,
+                new IPEndPoint(IPAddress.Loopback, 65_000),
+                new PublishedSession(registration),
+                joins,
+                FastOptions(),
+                clock,
+                tickets);
+            List<RendezvousHostAttemptCompletedEventArgs> completions = [];
+            host.AttemptCompleted += (_, completion) => completions.Add(completion);
+            Assert.True((await host.RefreshJoinAttemptsAsync()).IsSuccess);
+            host.Poll();
+            bool observedDeferredRequest = false;
+            hostEvents.RendezvousConnectionRequest += _ =>
+            {
+                observedDeferredRequest = host.DeferredRequestCount == 1;
+                ((INatPunchListener)hostPunch).OnNatIntroductionSuccess(
+                    new IPEndPoint(IPAddress.Loopback, clientManager.LocalPort),
+                    NatAddressType.External,
+                    grant.Ticket);
+            };
+
+            clientManager.Connect(
+                new IPEndPoint(IPAddress.Loopback, hostManager.LocalPort),
+                DirectConnectionRequestCodec.Encode(created.AttemptId, grant.Ticket));
+            DateTime connectedDeadline = DateTime.UtcNow.AddSeconds(1);
+            while ((!clientConnected || completions.Count == 0)
+                   && DateTime.UtcNow < connectedDeadline)
+            {
+                host.Poll();
+                clientManager.PollEvents();
+                await Task.Delay(2);
+            }
+
+            Assert.True(
+                clientConnected,
+                $"Deferred observed={observedDeferredRequest}; deferred={host.DeferredRequestCount}; "
+                + $"pending={host.PendingAttemptCount}; completions={completions.Count}.");
+            Assert.True(observedDeferredRequest);
+            Assert.Equal(0, host.DeferredRequestCount);
+            Assert.Equal(
+                RendezvousConnectionState.Connected,
+                Assert.Single(completions).State);
+        }
+        finally
+        {
+            hostManager.Stop();
+            clientManager.Stop();
+        }
+    }
+
+    private static RendezvousCoordinatorOptions FastOptions() => new()
+    {
+        MaximumPunchRequests = 20,
+        InitialPunchRetryDelay = TimeSpan.FromMilliseconds(10),
+        MaximumPunchRetryDelay = TimeSpan.FromMilliseconds(100),
+        JitterRatio = 0,
+    };
+
+    private sealed class FakeJoinClient(IReadOnlyList<HostJoinAttempt> attempts) : IRendezvousJoinClient
+    {
+        public Task<RendezvousConnectionStartResult> CreateConnectionAttemptAsync(
+            CreateJoinAttemptRequest request,
+            NetworkEndpoint? dedicatedFallback = null,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
+            CreateJoinAttemptRequest request,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<bool>> CancelAsync(
+            CreateJoinAttemptResponse attempt,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
+            PublishedSession session,
+            int pageSize = ContractLimits.BrowserPageMaxItems,
+            string? cursor = null,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+
+        public Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
+            PublishedSession session,
+            int maximumPages = 100,
+            CancellationToken cancellationToken = default) => Task.FromResult(
+                RendezvousClientResult.Success(attempts));
+
+        public Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
+            CreateJoinAttemptResponse attempt,
+            RendezvousConnectionOutcome outcome,
+            CancellationToken cancellationToken = default) => throw new NotSupportedException();
+    }
+
+    private sealed class FixedCoordinatorClock(DateTimeOffset now) :
+        IRendezvousCoordinatorClock,
+        IConnectionTicketClock
+    {
+        public DateTimeOffset UtcNow { get; } = now;
+        public TimeSpan Elapsed => TimeSpan.Zero;
+    }
+}

tests/FinalFactory.Rendezvous.Tests/Client/RendezvousJoinClientTests.cs

@@ -0,0 +1,290 @@
+using System.Net;
+using System.Text.Json;
+using FinalFactory.Rendezvous.Client;
+using FinalFactory.Rendezvous.Contracts;
+
+namespace FinalFactory.Rendezvous.Tests.Client;
+
+public sealed class RendezvousJoinClientTests
+{
+    [Fact]
+    public async Task JoinIssuanceRetriesTheSameIdempotentPayloadAndCancellationUsesCapability()
+    {
+        CreateJoinAttemptResponse created = CreateAttempt();
+        RecordingHandler handler = new(
+            new HttpResponseMessage(HttpStatusCode.ServiceUnavailable),
+            JsonResponse(HttpStatusCode.Created, created),
+            new HttpResponseMessage(HttpStatusCode.NoContent));
+        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
+        RendezvousJoinClient client = new(
+            http,
+            new RendezvousClientOptions { JitterRatio = 0 },
+            new ImmediateDelay());
+        CreateJoinAttemptRequest request = new()
+        {
+            IdempotencyKey = "stable-join-key",
+            GameId = new("space-game"),
+            EnvironmentId = new("production"),
+            ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000201")),
+            ProtocolVersion = 7,
+        };
+
+        RendezvousClientResult<CreateJoinAttemptResponse> result = await client.CreateAsync(request);
+        RendezvousClientResult<bool> cancelled = await client.CancelAsync(created);
+
+        Assert.True(result.IsSuccess, result.Message);
+        Assert.True(cancelled.IsSuccess, cancelled.Message);
+        Assert.Equal(handler.Requests[0].Body, handler.Requests[1].Body);
+        Assert.Contains("stable-join-key", handler.Requests[0].Body, StringComparison.Ordinal);
+        RecordedRequest cancellation = handler.Requests[2];
+        Assert.Equal(HttpMethod.Delete, cancellation.Method);
+        Assert.Equal(
+            created.ClientPunchCapability,
+            cancellation.Headers["X-Rendezvous-Client-Punch-Capability"]);
+    }
+
+    [Fact]
+    public async Task HostInvitationPollingFollowsCursorsWithTheLeaseToken()
+    {
+        HostJoinAttempt first = CreateHostAttempt("00000000-0000-0000-0000-000000000211");
+        HostJoinAttempt second = CreateHostAttempt("00000000-0000-0000-0000-000000000212");
+        RecordingHandler handler = new(
+            JsonResponse(HttpStatusCode.OK, new BrowseHostJoinAttemptsResponse
+            {
+                Items = [first],
+                NextCursor = "next page+cursor",
+            }),
+            JsonResponse(HttpStatusCode.OK, new BrowseHostJoinAttemptsResponse
+            {
+                Items = [second],
+            }));
+        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
+        RendezvousJoinClient client = new(http);
+        PublishedSession session = new(new RegisterSessionResponse
+        {
+            ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000220")),
+            LeaseId = new(Guid.Parse("00000000-0000-0000-0000-000000000221")),
+            LeaseToken = "lease-secret",
+            HostPresenceHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000222")),
+            HostPresenceCapability = Credential('P'),
+            ExpiresAt = new DateTimeOffset(2030, 1, 1, 0, 0, 0, TimeSpan.Zero),
+            LeaseRenewAfterSeconds = 15,
+            HostPresenceRefreshAfterSeconds = 10,
+        });
+
+        RendezvousClientResult<IReadOnlyList<HostJoinAttempt>> result =
+            await client.BrowseAllForHostAsync(session);
+
+        Assert.True(result.IsSuccess, result.Message);
+        Assert.Equal([first.AttemptId, second.AttemptId], result.Value!.Select(item => item.AttemptId));
+        Assert.Equal(2, handler.Requests.Count);
+        Assert.All(handler.Requests, request =>
+            Assert.Equal("lease-secret", request.Headers["X-Rendezvous-Lease-Token"]));
+        Assert.Contains("cursor=next%20page%2Bcursor", handler.Requests[1].Uri.Query, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public async Task OutcomeReportingUsesTheAttemptCapabilityAndCoarseElapsedBucket()
+    {
+        CreateJoinAttemptResponse attempt = CreateAttempt();
+        RecordingHandler handler = new(JsonResponse(HttpStatusCode.OK, new ReportConnectionOutcomeResponse
+        {
+            Accepted = true,
+            IsDuplicate = false,
+        }));
+        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
+        RendezvousJoinClient client = new(http);
+        RendezvousConnectionOutcome outcome = RendezvousConnectionOutcome.Create(
+            ConnectionOutcomeKind.DirectConnectTimedOut,
+            RendezvousConnectionOutcomeSource.LocalTraversal,
+            RendezvousConnectionFailureCategory.DirectConnection,
+            RendezvousConnectionPhase.DirectConnection,
+            TimeSpan.FromSeconds(6));
+
+        RendezvousClientResult<ReportConnectionOutcomeResponse> result =
+            await client.ReportOutcomeAsync(attempt, outcome);
+
+        Assert.True(result.IsSuccess, result.Message);
+        RecordedRequest request = Assert.Single(handler.Requests);
+        Assert.Equal(HttpMethod.Post, request.Method);
+        Assert.Equal(
+            attempt.ClientPunchCapability,
+            request.Headers["X-Rendezvous-Client-Punch-Capability"]);
+        Assert.Contains("\"outcome\":\"directConnectTimedOut\"", request.Body, StringComparison.Ordinal);
+        Assert.Contains("\"elapsedBucket\":\"fiveToFifteenSeconds\"", request.Body, StringComparison.Ordinal);
+        Assert.DoesNotContain("diagnostic", request.Body, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public async Task ConnectionStartReturnsATypedServiceOutcomeInsteadOfAnUnboundedFailure()
+    {
+        RecordingHandler handler = new(JsonResponse(HttpStatusCode.NotFound, new ApiError
+        {
+            Code = RendezvousErrorCode.NotFound,
+            Message = "listing unavailable",
+        }));
+        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
+        RendezvousJoinClient client = new(http);
+        NetworkEndpoint fallback = new()
+        {
+            AddressFamily = AddressFamilyKind.Ipv4,
+            Address = "203.0.113.93",
+            Port = 9_063,
+        };
+
+        RendezvousConnectionStartResult result = await client.CreateConnectionAttemptAsync(
+            new CreateJoinAttemptRequest
+            {
+                IdempotencyKey = "typed-start",
+                GameId = new("space-game"),
+                EnvironmentId = new("production"),
+                ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000230")),
+                ProtocolVersion = 7,
+            },
+            fallback);
+
+        Assert.True(result.IsCompleted);
+        Assert.False(result.IsReadyForTraversal);
+        Assert.Null(result.Attempt);
+        Assert.Equal(ConnectionOutcomeKind.DirectoryNotFound, result.Outcome!.Kind);
+        Assert.Equal("203.0.113.93", result.Outcome.DedicatedFallback!.Address);
+    }
+
+    [Fact]
+    public async Task ConnectionStartReturnsCancelledForAPrecancelledCallerToken()
+    {
+        RecordingHandler handler = new();
+        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
+        RendezvousJoinClient client = new(http);
+        using CancellationTokenSource cancellation = new();
+        cancellation.Cancel();
+
+        RendezvousConnectionStartResult result = await client.CreateConnectionAttemptAsync(
+            CreateRequest("cancelled-before-send"),
+            new NetworkEndpoint
+            {
+                AddressFamily = AddressFamilyKind.Ipv4,
+                Address = "203.0.113.90",
+                Port = 7777,
+            },
+            cancellationToken: cancellation.Token);
+
+        Assert.Empty(handler.Requests);
+        Assert.Equal(ConnectionOutcomeKind.Cancelled, result.Outcome!.Kind);
+        Assert.True(result.Outcome.HasDedicatedFallback);
+        Assert.Equal(RendezvousConnectionOutcomeSource.Caller, result.Outcome.Source);
+    }
+
+    [Fact]
+    public async Task ConnectionStartReturnsCancelledWhenCallerStopsASilentRequest()
+    {
+        CancellingHandler handler = new();
+        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
+        RendezvousJoinClient client = new(http);
+        using CancellationTokenSource cancellation = new();
+        Task<RendezvousConnectionStartResult> pending = client.CreateConnectionAttemptAsync(
+            CreateRequest("cancelled-in-flight"),
+            cancellationToken: cancellation.Token);
+        await handler.Started.Task.WaitAsync(TimeSpan.FromSeconds(2));
+
+        await cancellation.CancelAsync();
+        RendezvousConnectionStartResult result = await pending;
+
+        Assert.Equal(ConnectionOutcomeKind.Cancelled, result.Outcome!.Kind);
+        Assert.Equal(RendezvousConnectionOutcomeSource.Caller, result.Outcome.Source);
+    }
+
+    private static CreateJoinAttemptResponse CreateAttempt() => new()
+    {
+        AttemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000202")),
+        MediationHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000203")),
+        ClientPunchCapability = Credential('C'),
+        ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
+            NatIntroductionTokenCodec.Encode(
+                new JoinAttemptId(Guid.Parse("00000000-0000-0000-0000-000000000202")),
+                Credential('T'))),
+        ExpiresAt = new DateTimeOffset(2030, 1, 1, 0, 0, 30, TimeSpan.Zero),
+    };
+
+    private static CreateJoinAttemptRequest CreateRequest(string idempotencyKey) => new()
+    {
+        IdempotencyKey = idempotencyKey,
+        GameId = new("space-game"),
+        EnvironmentId = new("production"),
+        ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000230")),
+        ProtocolVersion = 7,
+    };
+
+    private static HostJoinAttempt CreateHostAttempt(string id) => new()
+    {
+        AttemptId = new(Guid.Parse(id)),
+        MediationHandle = new(Guid.NewGuid()),
+        HostPunchCapability = Credential('H'),
+        ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
+            NatIntroductionTokenCodec.Encode(new JoinAttemptId(Guid.Parse(id)), Credential('T'))),
+        ExpiresAt = new DateTimeOffset(2030, 1, 1, 0, 0, 30, TimeSpan.Zero),
+    };
+
+    private static string Credential(char value) => new(value, ContractLimits.DerivedCredentialCharacters);
+
+    private static HttpResponseMessage JsonResponse<T>(HttpStatusCode status, T value) => new(status)
+    {
+        Content = new ByteArrayContent(JsonSerializer.SerializeToUtf8Bytes(value, ContractJson.Options)),
+    };
+
+    private sealed class RecordingHandler(params HttpResponseMessage[] responses) : HttpMessageHandler
+    {
+        private readonly Queue<HttpResponseMessage> _responses = new(responses);
+
+        internal List<RecordedRequest> Requests { get; } = [];
+
+        protected override async Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request,
+            CancellationToken cancellationToken)
+        {
+            Dictionary<string, string> headers = request.Headers.ToDictionary(
+                static item => item.Key,
+                static item => string.Join(",", item.Value),
+                StringComparer.OrdinalIgnoreCase);
+            Requests.Add(new(
+                request.Method,
+                request.RequestUri!,
+                headers,
+                request.Content is null
+                    ? string.Empty
+                    : await request.Content.ReadAsStringAsync(cancellationToken)));
+            return _responses.Dequeue();
+        }
+    }
+
+    private sealed class CancellingHandler : HttpMessageHandler
+    {
+        internal TaskCompletionSource Started { get; } = new(
+            TaskCreationOptions.RunContinuationsAsynchronously);
+
+        protected override async Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request,
+            CancellationToken cancellationToken)
+        {
+            _ = request;
+            Started.TrySetResult();
+            await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
+            throw new InvalidOperationException("The silent request unexpectedly completed.");
+        }
+    }
+
+    private sealed record RecordedRequest(
+        HttpMethod Method,
+        Uri Uri,
+        IReadOnlyDictionary<string, string> Headers,
+        string Body);
+
+    private sealed class ImmediateDelay : IRendezvousDelay
+    {
+        public Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            return Task.CompletedTask;
+        }
+    }
+}

tests/FinalFactory.Rendezvous.Tests/ConnectionOutcomes/ConnectionOutcomeServiceTests.cs

@@ -0,0 +1,175 @@
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.ConnectionOutcomes;
+using FinalFactory.Rendezvous.Tests.JoinAttempts;
+
+namespace FinalFactory.Rendezvous.Tests.ConnectionOutcomes;
+
+public sealed class ConnectionOutcomeServiceTests
+{
+    [Fact]
+    public void ReportRemainsAuthenticatedAfterAttemptExpiryAndCountsOnlyOnce()
+    {
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse attempt = fixture.Create(registration.ListingId);
+        ConnectionOutcomeMetrics metrics = new();
+        ConnectionOutcomeService service = new(
+            fixture.Sessions.Store,
+            fixture.Sessions.Capabilities,
+            metrics);
+        ReportConnectionOutcomeRequest report = new()
+        {
+            Outcome = ConnectionOutcomeKind.PunchTimedOut,
+            ElapsedBucket = ConnectionElapsedBucket.FiveToFifteenSeconds,
+        };
+        fixture.Sessions.Clock.Advance(fixture.Sessions.StoreOptions.JoinAttemptLifetime);
+
+        ConnectionOutcomeServiceResult first = service.Report(
+            attempt.AttemptId,
+            attempt.ClientPunchCapability,
+            report);
+        ConnectionOutcomeServiceResult duplicate = service.Report(
+            attempt.AttemptId,
+            attempt.ClientPunchCapability,
+            report);
+        ConnectionOutcomeServiceResult conflict = service.Report(
+            attempt.AttemptId,
+            attempt.ClientPunchCapability,
+            new ReportConnectionOutcomeRequest
+            {
+                Outcome = ConnectionOutcomeKind.Connected,
+                ElapsedBucket = ConnectionElapsedBucket.FiveToFifteenSeconds,
+            });
+
+        Assert.True(first.Succeeded);
+        Assert.False(first.Value!.IsDuplicate);
+        Assert.True(duplicate.Succeeded);
+        Assert.True(duplicate.Value!.IsDuplicate);
+        Assert.Equal(RendezvousErrorCode.ReplayRejected, conflict.Error);
+        Assert.Equal(
+            1,
+            metrics.GetCount(
+                ConnectionOutcomeKind.PunchTimedOut,
+                ConnectionElapsedBucket.FiveToFifteenSeconds));
+        Assert.Equal(
+            RendezvousErrorCode.NotFound,
+            service.Report(
+                attempt.AttemptId,
+                new string('X', ContractLimits.DerivedCredentialCharacters),
+                report).Error);
+    }
+
+    [Theory]
+    [InlineData(ConnectionOutcomeKind.DirectoryNotFound)]
+    [InlineData(ConnectionOutcomeKind.IncompatibleProtocol)]
+    [InlineData(ConnectionOutcomeKind.Unauthorized)]
+    [InlineData(ConnectionOutcomeKind.RateLimited)]
+    public void ReportRejectsOutcomesThatCouldNotHaveAnIssuedAttempt(
+        ConnectionOutcomeKind outcome)
+    {
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse attempt = fixture.Create(registration.ListingId);
+        ConnectionOutcomeService service = new(
+            fixture.Sessions.Store,
+            fixture.Sessions.Capabilities,
+            new ConnectionOutcomeMetrics());
+
+        ConnectionOutcomeServiceResult result = service.Report(
+            attempt.AttemptId,
+            attempt.ClientPunchCapability,
+            new ReportConnectionOutcomeRequest
+            {
+                Outcome = outcome,
+                ElapsedBucket = ConnectionElapsedBucket.UnderOneSecond,
+            });
+
+        Assert.Equal(RendezvousErrorCode.InvalidRequest, result.Error);
+    }
+
+    [Fact]
+    public void ListingDeletionRemovesRetainedOutcomeAuthorization()
+    {
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse attempt = fixture.Create(registration.ListingId);
+        ConnectionOutcomeService service = new(
+            fixture.Sessions.Store,
+            fixture.Sessions.Capabilities,
+            new ConnectionOutcomeMetrics());
+
+        Assert.True(fixture.Sessions.Store.RevokeListing(registration.ListingId).Succeeded);
+
+        Assert.Equal(
+            RendezvousErrorCode.NotFound,
+            service.Report(
+                attempt.AttemptId,
+                attempt.ClientPunchCapability,
+                new ReportConnectionOutcomeRequest
+                {
+                    Outcome = ConnectionOutcomeKind.Cancelled,
+                    ElapsedBucket = ConnectionElapsedBucket.UnderOneSecond,
+                }).Error);
+    }
+
+    [Fact]
+    public void PrincipalRevocationRemovesReportAuthorizationAfterAttemptExpiry()
+    {
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse attempt = fixture.Create(registration.ListingId);
+        ConnectionOutcomeService service = new(
+            fixture.Sessions.Store,
+            fixture.Sessions.Capabilities,
+            new ConnectionOutcomeMetrics());
+        fixture.Sessions.Clock.Advance(fixture.Sessions.StoreOptions.JoinAttemptLifetime);
+
+        Assert.True(fixture.Sessions.Store.RevokePrincipal(
+            fixture.ClientSubject,
+            TimeSpan.FromMinutes(1)).Succeeded);
+
+        Assert.Equal(
+            RendezvousErrorCode.NotFound,
+            service.Report(
+                attempt.AttemptId,
+                attempt.ClientPunchCapability,
+                new ReportConnectionOutcomeRequest
+                {
+                    Outcome = ConnectionOutcomeKind.Cancelled,
+                    ElapsedBucket = ConnectionElapsedBucket.UnderOneSecond,
+                }).Error);
+    }
+
+    [Fact]
+    public void FrozenV1ReportFieldsAreAcceptedButNormalizedBeforeRetention()
+    {
+        using JoinAttemptFixture fixture = new();
+        (RegisterSessionResponse registration, _) = fixture.CreateHost();
+        CreateJoinAttemptResponse attempt = fixture.Create(registration.ListingId);
+        ConnectionOutcomeMetrics metrics = new();
+        ConnectionOutcomeService service = new(
+            fixture.Sessions.Store,
+            fixture.Sessions.Capabilities,
+            metrics);
+#pragma warning disable CS0618 // Deliberately exercises the frozen legacy input surface.
+        ReportConnectionOutcomeRequest legacy = new()
+        {
+            Outcome = ConnectionOutcomeKind.TimedOut,
+            ElapsedMilliseconds = 6_000,
+            DiagnosticCode = "legacy-text-is-discarded",
+        };
+#pragma warning restore CS0618
+
+        ConnectionOutcomeServiceResult result = service.Report(
+            attempt.AttemptId,
+            attempt.ClientPunchCapability,
+            legacy);
+
+        Assert.True(result.Succeeded);
+        Assert.Equal(
+            1,
+            metrics.GetCount(
+                ConnectionOutcomeKind.PunchTimedOut,
+                ConnectionElapsedBucket.FiveToFifteenSeconds));
+    }
+}

tests/FinalFactory.Rendezvous.Tests/Contracts/ContractSerializationTests.cs

@@ -70,10 +70,10 @@ public sealed class ContractSerializationTests
     public void UnknownEnumNamesAndNumericValuesAreRejected()
     {
         Assert.Throws<JsonException>(() => JsonSerializer.Deserialize<ReportConnectionOutcomeRequest>(
-            "{\"contractVersion\":1,\"outcome\":\"futureOutcome\",\"elapsedMilliseconds\":1}",
+            "{\"contractVersion\":1,\"outcome\":\"futureOutcome\",\"elapsedBucket\":\"underOneSecond\"}",
             ContractJson.Options));
         Assert.Throws<JsonException>(() => JsonSerializer.Deserialize<ReportConnectionOutcomeRequest>(
-            "{\"contractVersion\":1,\"outcome\":99,\"elapsedMilliseconds\":1}",
+            "{\"contractVersion\":1,\"outcome\":99,\"elapsedBucket\":\"underOneSecond\"}",
             ContractJson.Options));
     }
 
@@ -98,6 +98,7 @@ public sealed class ContractSerializationTests
     [Fact]
     public void SharedCanonicalOptionsCannotBeMutatedByConsumers()
     {
+        Assert.Equal(9, ContractJson.Options.MaxDepth);
         Assert.True(ContractJson.Options.IsReadOnly);
         Assert.Throws<InvalidOperationException>(() =>
             ContractJson.Options.WriteIndented = true);