M51: record zero-error rollout acceptance

PROJECT_STATE.md

@@ -1,5 +1,22 @@
 # Project state
 
+## M51 — zero-error production rollout evidence (2026-08-21)
+
+- The rejected M49 candidate proved rollback isolation: production remained on M48 and
+  **500/500** external probes succeeded. M50 revision
+  `cea0825d6094e2981452fd179dd5d9f8724766d0` then promoted successfully from archive
+  SHA-256 `6148de2ea7966d1527b28d769048b4b6cf8a7cfc699f2e5cb568e7504efc4693`.
+- The established gateway stayed online throughout M50 promotion: **700/700** external
+  probes passed with zero interruption. Exactly two M50 API and two M50 web replicas serve
+  behind it; no rejected M49 candidate remains. Database, backup, Prometheus, Alertmanager,
+  Grafana and gateway all remain healthy.
+- Post-promotion live acceptance passed **4/4** in Chromium/Firefox, including the grounded
+  production knowledge path. The 360-request authenticated read gate again had zero errors
+  at concurrency 18, p95 **116.4 ms** and max **144.6 ms**.
+- Exact next action: commit/push this evidence-only M51 revision, deploy it through the same
+  verified gateway path, confirm exact revision/readiness and tag `v1.1.0-poc`. OneDrive is
+  fully prepared but remains disabled until the owner completes Microsoft OAuth once.
+
 ## M50 — preserve web/API compatibility alias during rollout (2026-08-21)
 
 - The first steady-gateway M49 rollout correctly kept M48 serving when both candidate web

artifacts/final-acceptance/summary.md

@@ -43,6 +43,10 @@ in `PROJECT_STATE.md`.
 - Moving host port 1236 from the legacy web container to the gateway was a one-time
   migration hand-off and produced 14 failures across 1,200 rapid probes. Future releases
   do not move that port; their acceptance gate is the zero-error versioned gateway reload.
+- The subsequent M50 release exercised that steady-state path: the gateway remained online,
+  atomically switched revision-specific API/web aliases and sustained **700/700** external
+  readiness probes without interruption. Post-promotion Chromium/Firefox acceptance passed
+  **4/4** and 360 concurrent authenticated reads had zero errors at p95 **116.4 ms**.
 - The versioned gateway switch sustained **300/300** local rollout probes without an error.
   Production's non-destructive Chromium/Firefox canary passed **4/4**, and 360 authenticated
   concurrent reads returned zero errors at p95 **137.2 ms**.