chore: complete v1.0 Analytics & Monitoring milestone

Archive milestone artifacts (roadmap, requirements, audit, phase directories)
to .planning/milestones/. Evolve PROJECT.md with validated requirements and
decision outcomes. Create MILESTONES.md and RETROSPECTIVE.md.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/milestones/v1.0-phases/03-api-layer/03-02-SUMMARY.md

@@ -0,0 +1,109 @@
+---
+phase: 03-api-layer
+plan: 02
+subsystem: api
+tags: [analytics, instrumentation, fire-and-forget, document-processing]
+
+# Dependency graph
+requires:
+  - phase: 02-backend-services
+    provides: analyticsService.recordProcessingEvent() fire-and-forget function
+  - phase: 03-api-layer/03-01
+    provides: analytics endpoint that reads document_processing_events table
+provides:
+  - Analytics instrumentation at 3 lifecycle points in processJob()
+  - document_processing_events table populated with real processing data
+affects: [03-api-layer, 03-01-analytics-endpoint]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - Fire-and-forget analytics calls (void return, no await) in processJob lifecycle
+
+key-files:
+  created: []
+  modified:
+    - backend/src/services/jobProcessorService.ts
+
+key-decisions:
+  - "All three recordProcessingEvent() calls are void/fire-and-forget (no await) — PITFALL-6 compliance confirmed"
+  - "upload_started event emitted after markAsProcessing (not processing_started) per locked decision"
+  - "Null-guard on job in catch block — job can be null if findById throws before assignment"
+
+patterns-established:
+  - "Analytics instrumentation pattern: call recordProcessingEvent() without await, no try/catch wrapper — function handles errors internally"
+
+requirements-completed: [ANLY-02]
+
+# Metrics
+duration: 2min
+completed: 2026-02-24
+---
+
+# Phase 3 Plan 02: Analytics Instrumentation Summary
+
+**Three fire-and-forget recordProcessingEvent() calls added to processJob() at upload_started, completed, and failed lifecycle points**
+
+## Performance
+
+- **Duration:** 2 min
+- **Started:** 2026-02-24T20:42:54Z
+- **Completed:** 2026-02-24T20:44:36Z
+- **Tasks:** 1
+- **Files modified:** 1
+
+## Accomplishments
+
+- Added import for `recordProcessingEvent` from analyticsService at top of jobProcessorService.ts
+- Emits `upload_started` event (fire-and-forget) after `markAsProcessing` at job start
+- Emits `completed` event with `duration_ms` (fire-and-forget) after `markAsCompleted` on success
+- Emits `failed` event with `duration_ms` and `error_message` (fire-and-forget) in catch block with null-guard
+- Zero regressions — all 64 existing tests pass, TypeScript compiles cleanly
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add analytics instrumentation to processJob lifecycle** - `dabd4a5` (feat)
+
+**Plan metadata:** (docs commit follows)
+
+## Files Created/Modified
+
+- `backend/src/services/jobProcessorService.ts` - Added import and 3 recordProcessingEvent() instrumentation calls at job start, completion, and failure
+
+## Decisions Made
+
+- Confirmed `event_type: 'upload_started'` (not `'processing_started'`) matches the locked analytics schema decision
+- No await on any recordProcessingEvent() call — void return type enforces fire-and-forget at the type system level
+- Null-guard `if (job)` in catch block is necessary because `job` remains `null` if `ProcessingJobModel.findById()` throws before assignment
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None.
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+
+- Analytics pipeline is now end-to-end: document_processing_events table receives real data when jobs run
+- GET /admin/analytics endpoint (03-01) will report actual processing metrics instead of zeros
+- No blockers for remaining Phase 03 plans
+
+## Self-Check: PASSED
+
+- FOUND: backend/src/services/jobProcessorService.ts
+- FOUND: .planning/phases/03-api-layer/03-02-SUMMARY.md
+- FOUND commit: dabd4a5 (feat: analytics instrumentation)
+- FOUND commit: 081c535 (docs: plan metadata)
+
+---
+*Phase: 03-api-layer*
+*Completed: 2026-02-24*