docs(observability): document phase-0 telemetry and baseline workflow

docs/architecture/GATEWAY_SESSIONS_AND_QUEUE.md

@@ -14,6 +14,7 @@ If you only want the protocol surface, see `docs/api/PROTOCOL.md`.
 - Runtime backend mode can be overridden manually via `/runtime` command fast-path (`status`, `activate pi`, `deactivate pi`, `use config`) and is persisted in preferences (`/backend` remains a compatibility alias).
 - `flynn tui` now attaches to this same gateway command path for `/runtime ...` and auto-starts/attaches daemon+gateway when needed.
 - Backend routing outcomes are auditable via `backend.route` / `backend.success` / `backend.fallback`, which enables offline canary evaluation without changing gateway protocol methods.
+- Run lifecycle/cancel intent and reaction decisions are emitted to audit logs, and aggregated into `system.metrics` counters (runStates, cancelLatencyMs, reactions) for dashboards.
 
 ## Component Map
 
@@ -31,6 +32,8 @@ flowchart LR
     LQ[LaneQueue\nper-session FIFO]
     SB[SessionBridge\nconnectionId -> sessionId -> AgentOrchestrator]
     AQ[AuditLogger\nqueue.preempt events]
+    MC[MetricsCollector\nrun states + cancel latency + reactions]
+    UI[Web UI Dashboard]
   end
 
   subgraph CORE[Flynn Core]
@@ -46,6 +49,8 @@ flowchart LR
   GS --> LQ
   GS --> SB
   LQ --> AQ
+  GS --> MC
+  MC --> UI
 
   SB --> AO
   SB --> SM