---
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*