docs(08): create phase plan

Phase 08: Observability Stack
- 3 plans in 2 waves
- Wave 1: 08-01 (metrics), 08-02 (Alloy) - parallel
- Wave 2: 08-03 (verification) - depends on both
- Ready for execution

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

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

@@ -0,0 +1,174 @@
+---
+phase: 08-observability-stack
+plan: 01
+type: execute
+wave: 1
+depends_on: []
+files_modified:
+  - package.json
+  - src/routes/metrics/+server.ts
+  - src/lib/server/metrics.ts
+  - helm/taskplaner/templates/servicemonitor.yaml
+  - helm/taskplaner/values.yaml
+autonomous: true
+
+must_haves:
+  truths:
+    - "TaskPlanner /metrics endpoint returns Prometheus-format text"
+    - "ServiceMonitor exists in Helm chart templates"
+    - "Prometheus can discover TaskPlanner via ServiceMonitor"
+  artifacts:
+    - path: "src/routes/metrics/+server.ts"
+      provides: "Prometheus metrics HTTP endpoint"
+      exports: ["GET"]
+    - path: "src/lib/server/metrics.ts"
+      provides: "prom-client registry and metrics definitions"
+      contains: "collectDefaultMetrics"
+    - path: "helm/taskplaner/templates/servicemonitor.yaml"
+      provides: "ServiceMonitor for Prometheus Operator"
+      contains: "kind: ServiceMonitor"
+  key_links:
+    - from: "src/routes/metrics/+server.ts"
+      to: "src/lib/server/metrics.ts"
+      via: "import register"
+      pattern: "import.*register.*from.*metrics"
+    - from: "helm/taskplaner/templates/servicemonitor.yaml"
+      to: "tp-app service"
+      via: "selector matchLabels"
+      pattern: "selector.*matchLabels"
+---
+
+<objective>
+Add Prometheus metrics endpoint to TaskPlanner and ServiceMonitor for scraping
+
+Purpose: Enable Prometheus to collect application metrics from TaskPlanner (OBS-08, OBS-01)
+Output: /metrics endpoint returning prom-client default metrics, ServiceMonitor in Helm chart
+</objective>
+
+<execution_context>
+@/home/tho/.claude/get-shit-done/workflows/execute-plan.md
+@/home/tho/.claude/get-shit-done/templates/summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+@.planning/phases/08-observability-stack/CONTEXT.md
+@package.json
+@src/routes/health/+server.ts
+@helm/taskplaner/values.yaml
+@helm/taskplaner/templates/service.yaml
+</context>
+
+<tasks>
+
+<task type="auto">
+  <name>Task 1: Add prom-client and create /metrics endpoint</name>
+  <files>
+    package.json
+    src/lib/server/metrics.ts
+    src/routes/metrics/+server.ts
+  </files>
+  <action>
+    1. Install prom-client:
+       ```bash
+       npm install prom-client
+       ```
+
+    2. Create src/lib/server/metrics.ts:
+       - Import prom-client's Registry, collectDefaultMetrics
+       - Create a new Registry instance
+       - Call collectDefaultMetrics({ register: registry }) to collect Node.js process metrics
+       - Export the registry
+       - Keep it minimal - just default metrics (memory, CPU, event loop lag)
+
+    3. Create src/routes/metrics/+server.ts:
+       - Import the registry from $lib/server/metrics
+       - Create GET handler that returns registry.metrics() with Content-Type: text/plain; version=0.0.4
+       - Handle errors gracefully (return 500 on failure)
+       - Pattern follows existing /health endpoint structure
+
+    NOTE: prom-client is the standard Node.js Prometheus client. Use default metrics only - no custom metrics needed for this phase.
+  </action>
+  <verify>
+    1. npm run build completes without errors
+    2. npm run dev, then curl http://localhost:5173/metrics returns text starting with "# HELP" or "# TYPE"
+    3. Response Content-Type header includes "text/plain"
+  </verify>
+  <done>
+    /metrics endpoint returns Prometheus-format metrics including process_cpu_seconds_total, nodejs_heap_size_total_bytes
+  </done>
+</task>
+
+<task type="auto">
+  <name>Task 2: Add ServiceMonitor to Helm chart</name>
+  <files>
+    helm/taskplaner/templates/servicemonitor.yaml
+    helm/taskplaner/values.yaml
+  </files>
+  <action>
+    1. Create helm/taskplaner/templates/servicemonitor.yaml:
+       ```yaml
+       {{- if .Values.metrics.enabled }}
+       apiVersion: monitoring.coreos.com/v1
+       kind: ServiceMonitor
+       metadata:
+         name: {{ include "taskplaner.fullname" . }}
+         labels:
+           {{- include "taskplaner.labels" . | nindent 4 }}
+       spec:
+         selector:
+           matchLabels:
+             {{- include "taskplaner.selectorLabels" . | nindent 6 }}
+         endpoints:
+           - port: http
+             path: /metrics
+             interval: {{ .Values.metrics.interval | default "30s" }}
+         namespaceSelector:
+           matchNames:
+             - {{ .Release.Namespace }}
+       {{- end }}
+       ```
+
+    2. Update helm/taskplaner/values.yaml - add metrics section:
+       ```yaml
+       # Prometheus metrics
+       metrics:
+         enabled: true
+         interval: 30s
+       ```
+
+    3. Ensure the service template exposes port named "http" (check existing service.yaml - it likely already does via targetPort: http)
+
+    NOTE: The ServiceMonitor uses monitoring.coreos.com/v1 API which kube-prometheus-stack provides. The namespaceSelector ensures Prometheus finds TaskPlanner in the default namespace.
+  </action>
+  <verify>
+    1. helm template ./helm/taskplaner includes ServiceMonitor resource
+    2. helm template output shows selector matching app.kubernetes.io/name: taskplaner
+    3. No helm lint errors
+  </verify>
+  <done>
+    ServiceMonitor template renders correctly with selector matching TaskPlanner service, ready for Prometheus to discover
+  </done>
+</task>
+
+</tasks>
+
+<verification>
+- [ ] npm run build succeeds
+- [ ] curl localhost:5173/metrics returns Prometheus-format text
+- [ ] helm template ./helm/taskplaner shows ServiceMonitor resource
+- [ ] ServiceMonitor selector matches service labels
+</verification>
+
+<success_criteria>
+1. /metrics endpoint returns Prometheus-format metrics (process metrics, heap size, event loop)
+2. ServiceMonitor added to Helm chart templates
+3. ServiceMonitor enabled by default in values.yaml
+4. Build and type check pass
+</success_criteria>
+
+<output>
+After completion, create `.planning/phases/08-observability-stack/08-01-SUMMARY.md`
+</output>