docs(08-01): complete TaskPlanner metrics and ServiceMonitor plan

Tasks completed: 2/2
- Add prom-client and create /metrics endpoint
- Add ServiceMonitor to Helm chart

SUMMARY: .planning/phases/08-observability-stack/08-01-SUMMARY.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.planning/STATE.md

@@ -5,16 +5,16 @@
 See: .planning/PROJECT.md (updated 2026-02-01)
 
 **Core value:** Capture and find anything from any device — especially laptop. If cross-device capture with images doesn't work, nothing else matters.
-**Current focus:** v2.0 Production Operations — Phase 8 (Logging)
+**Current focus:** v2.0 Production Operations — Phase 8 (Observability Stack)
 
 ## Current Position
 
-Phase: 7 of 9 (GitOps Foundation) - COMPLETE
+Phase: 8 of 9 (Observability Stack) - IN PROGRESS
-Plan: 2 of 2 in current phase - COMPLETE
+Plan: 1 of 3 in current phase - COMPLETE
-Status: Phase complete, ready for Phase 8
+Status: In progress
-Last activity: 2026-02-03 — Completed 07-02-PLAN.md (GitOps Verification)
+Last activity: 2026-02-03 — Completed 08-01-PLAN.md (TaskPlanner /metrics and ServiceMonitor)
 
-Progress: [████████████████████░░░░░░░░░░] 80% (20/25 plans complete)
+Progress: [█████████████████████░░░░░░░░░] 84% (21/25 plans complete)
 
 ## Performance Metrics
 
@@ -26,8 +26,8 @@ Progress: [████████████████████░░░
 - Requirements satisfied: 31/31
 
 **v2.0 Progress:**
-- Plans completed: 2/7
+- Plans completed: 3/7
-- Total execution time: 26 min
+- Total execution time: 30 min
 
 **By Phase (v1.0):**
 
@@ -45,6 +45,7 @@ Progress: [████████████████████░░░
 | Phase | Plans | Total | Avg/Plan |
 |-------|-------|-------|----------|
 | 07-gitops-foundation | 2/2 | 26 min | 13 min |
+| 08-observability-stack | 1/3 | 4 min | 4 min |
 
 ## Accumulated Context
 
@@ -67,6 +68,10 @@ For v2.0, key decisions from research:
 - GitOps verification pattern: Use pod annotation changes for non-destructive sync testing
 - ArgoCD health "Progressing" is display issue, not functional problem
 
+**From Phase 8-01:**
+- Use prom-client default metrics only (no custom metrics for initial setup)
+- ServiceMonitor enabled by default in values.yaml
+
 ### Pending Todos
 
 - Deploy Gitea Actions runner for automatic CI builds
@@ -78,10 +83,10 @@ For v2.0, key decisions from research:
 
 ## Session Continuity
 
-Last session: 2026-02-03 14:40 UTC
+Last session: 2026-02-03 21:08 UTC
-Stopped at: Completed 07-02-PLAN.md (Phase 7 complete)
+Stopped at: Completed 08-01-PLAN.md
 Resume file: None
 
 ---
 *State initialized: 2026-01-29*
-*Last updated: 2026-02-03 — Phase 7 GitOps Foundation complete*
+*Last updated: 2026-02-03 — Completed 08-01-PLAN.md (TaskPlanner /metrics and ServiceMonitor)*

.planning/phases/08-observability-stack/08-01-SUMMARY.md

@@ -0,0 +1,102 @@
+---
+phase: 08-observability-stack
+plan: 01
+subsystem: infra
+tags: [prometheus, prom-client, servicemonitor, metrics, kubernetes, helm]
+
+# Dependency graph
+requires:
+  - phase: 06-deployment
+    provides: Helm chart structure and Kubernetes deployment
+provides:
+  - Prometheus-format /metrics endpoint
+  - ServiceMonitor for Prometheus Operator discovery
+  - Default Node.js process metrics (CPU, memory, heap, event loop)
+affects: [08-02, 08-03, observability]
+
+# Tech tracking
+tech-stack:
+  added: [prom-client]
+  patterns: [metrics-endpoint, servicemonitor-discovery]
+
+key-files:
+  created:
+    - src/lib/server/metrics.ts
+    - src/routes/metrics/+server.ts
+    - helm/taskplaner/templates/servicemonitor.yaml
+  modified:
+    - package.json
+    - helm/taskplaner/values.yaml
+
+key-decisions:
+  - "Use prom-client default metrics only (no custom metrics for initial setup)"
+  - "ServiceMonitor enabled by default in values.yaml"
+
+patterns-established:
+  - "Metrics endpoint: server-side only route returning registry.metrics() with correct Content-Type"
+  - "ServiceMonitor: conditional on metrics.enabled, uses selectorLabels for pod discovery"
+
+# Metrics
+duration: 4min
+completed: 2026-02-03
+---
+
+# Phase 8 Plan 1: TaskPlanner /metrics endpoint and ServiceMonitor Summary
+
+**Prometheus /metrics endpoint with prom-client and ServiceMonitor for Prometheus Operator scraping**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-02-03T21:04:03Z
+- **Completed:** 2026-02-03T21:08:00Z
+- **Tasks:** 2
+- **Files modified:** 5
+
+## Accomplishments
+
+- /metrics endpoint returns Prometheus-format text including process_cpu_seconds_total, nodejs_heap_size_total_bytes
+- ServiceMonitor template renders correctly with selector matching TaskPlanner service
+- Metrics enabled by default in Helm chart (metrics.enabled: true)
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add prom-client and create /metrics endpoint** - `f60aad2` (feat)
+2. **Task 2: Add ServiceMonitor to Helm chart** - `f2a2893` (feat)
+
+## Files Created/Modified
+
+- `src/lib/server/metrics.ts` - Prometheus registry with default Node.js metrics
+- `src/routes/metrics/+server.ts` - GET handler returning metrics in Prometheus format
+- `helm/taskplaner/templates/servicemonitor.yaml` - ServiceMonitor for Prometheus Operator
+- `helm/taskplaner/values.yaml` - Added metrics.enabled and metrics.interval settings
+- `package.json` - Added prom-client dependency
+
+## Decisions Made
+
+- Used prom-client default metrics only (CPU, memory, heap, event loop) - no custom application metrics needed for initial observability setup
+- ServiceMonitor enabled by default since metrics endpoint is always available
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None - all verification checks passed.
+
+## User Setup Required
+
+None - no external service configuration required. The ServiceMonitor will be automatically discovered by Prometheus Operator once deployed via ArgoCD.
+
+## Next Phase Readiness
+
+- /metrics endpoint ready for Prometheus scraping
+- ServiceMonitor will be deployed with next ArgoCD sync
+- Ready for Phase 8-02: Promtail to Alloy migration
+
+---
+*Phase: 08-observability-stack*
+*Completed: 2026-02-03*