docs: resolve observability recovery audit

.scratch/saas-production-readiness/issues/04-define-observability-recovery.md

@@ -1,7 +1,7 @@
 # Define production observability and incident recovery
 
 Type: research
-Status: open
+Status: resolved
 Blocked by: 01, 02, 03
 
 ## Question
@@ -10,3 +10,38 @@ Which logs, metrics, readiness signals, audit correlations, alerts, and operator
 recovery actions are missing for a production operator to detect and diagnose
 failures across HTTP, Feishu, PostgreSQL, agent execution, cph builds, and
 workspace storage?
+
+## Answer
+
+The Hub has useful fragments—Fastify access logs, Prisma error/warn output,
+durable AgentRun facts, selected Feishu warnings, explicit migrations, and a
+systemd journal—but no joined operational contract. It has no metrics or alert
+surface, no end-to-end request/event/run/delivery/release correlation, no
+checked-in recovery runbooks, and many critical writes or sends are silently
+best-effort.
+
+Three process-level fault probes confirmed the release gate is actively
+misleading: cutting every PostgreSQL socket left `/api/healthz` at 200 twice;
+an SDK-rejected Feishu app ID also left health at 200; and a runtime database
+outage made `/api/me` return a raw Prisma invocation as `400 bad_request` with
+no request-scoped exception log. The current deploy check can therefore accept
+an instance unable to serve either database or Feishu work, while dependency
+failures evade normal 5xx alerting.
+
+The full failure-to-signal matrix, liveness/readiness/startup contract,
+correlation envelope, metric and alert inventory, required runbooks, executed
+probe evidence, primary sources, and minimum release evidence are in the
+[production observability and incident-recovery audit](../assets/production-observability-recovery.md).
+
+The newly-clear implementation and decision frontier is:
+
+- [Make HTTP dependency failures typed and observable](28-typed-observable-http-errors.md)
+- [Decide the telemetry, SLO, retention, and alerting control plane](29-decide-telemetry-slos-alert-routing.md)
+- [Instrument correlated production runtime telemetry](30-instrument-correlated-runtime-telemetry.md)
+- [Write and drill production incident recovery runbooks](31-write-and-drill-incident-runbooks.md)
+
+[Add real readiness and an accurate service lifecycle](13-real-readiness-and-lifecycle.md)
+owns component probes, Feishu connection state and deploy gating. Durable
+ingress/run/outbound recovery stays with tickets 23–25, audit semantics with
+ticket 27, and backup/restore guarantees with ticket 06; this audit does not
+duplicate those implementations.