fix: stream bash output and harden OpenCode connectivity (#2522)

* fix(ui): stream bash tool output while running

* perf(ui): render streaming bash output incrementally

* fix(ui): keep tool duration timer running

* fix(web): recover stalled OpenCode SSE streams

* fix(web): prevent OpenCode restart storms

* fix: address streaming recovery review

packages/web/server/lib/opencode/DOCUMENTATION.md

@@ -120,6 +120,8 @@ runtime. PATH and `OPENCODE_SERVER_PASSWORD` remain lifecycle-owned and cannot
 be replaced by injected values. External OpenCode processes receive no
 OpenChamber tool injection.
 
+Transport-triggered health checks share the periodic monitor's failure accounting interval. Rapid WS reconnect callbacks therefore cannot exhaust the managed-process restart threshold using one cached unhealthy result; an exited managed process still restarts immediately.
+
 ## Public exports (env-runtime.js)
 - `createOpenCodeEnvRuntime(dependencies)`: creates runtime that owns OpenCode CLI environment and binary discovery state.
 - OpenCode CLI resolution order is persisted settings, environment overrides, bundled Desktop CLI when available, PATH, known install locations, then platform shell discovery.
@@ -350,6 +352,7 @@ an authoritative loopback callback URL even when OpenChamber binds port `0`.
 - `registerOpenCodeProxy(app, dependencies)`: registers OpenCode proxy routes and middleware.
 - Owns:
   - SSE forwarders: `GET /api/global/event`, `GET /api/event`
+    - Downstream heartbeats keep clients and intermediaries alive, while a separate upstream-only stall watchdog closes the downstream response when OpenCode stops producing bytes so clients reconnect instead of trusting synthetic heartbeats indefinitely. Each watchdog reset uses the current load-aware timeout, matching the shared event transport.
   - Session message forwarder: `POST /api/session/:sessionId/message`
   - Generic `/api/*` forwarding with hop-by-hop header filtering
   - Windows `/session` merge fallback path behavior