---
phase: 12-telemetry-heartbeat
plan: 01
subsystem: monitoring
tags: [heartbeat, checksum, telemetry, jsonl, telegram]

requires:
  - phase: 09-checksum-registry
    provides: ChecksumRegistry API for querying verification state
  - phase: 10-seeder-checksum
    provides: Seeder checksum verification pipeline to wire telemetry into
  - phase: 11-integrity-sweep
    provides: Sweep verification pipeline to wire telemetry into
provides:
  - Heartbeat check module reading ChecksumRegistry and JSONL telemetry
  - Checksum Health section in Telegram heartbeat message
  - JSONL telemetry log for all checksum operations (seeder + sweep)
  - CRITICAL-tier LOUD alert on checksum failures
affects: [deploy, heartbeat]

tech-stack:
  added: []
  patterns: [exception-only heartbeat section, JSONL append-only telemetry]

key-files:
  created:
    - python/opendeviationbar/checksum_telemetry.py
    - scripts/heartbeat/checks/checksum.py
  modified:
    - scripts/heartbeat/checks/__init__.py
    - scripts/heartbeat/config.py
    - scripts/heartbeat/formatter.py
    - scripts/tick_cache_seeder.py
    - scripts/integrity_sweep.py

key-decisions:
  - "checksum_ok in CRITICAL_KEYS (not WARNING) -- checksum failure means potentially corrupted data, warrants LOUD alert per TELEM-02"

patterns-established:
  - "JSONL telemetry pattern: append-only log at ~/.cache/opendeviationbar/*.jsonl, fire-and-forget, never crashes caller"

requirements-completed: [TELEM-01, TELEM-02, TELEM-04]

duration: 4min
completed: 2026-03-26
---

# Phase 12 Plan 01: Checksum Telemetry & Heartbeat Monitoring Summary

**Checksum verification health monitoring in heartbeat with JSONL telemetry log and LOUD Telegram alerts on integrity failures**

## Performance

- **Duration:** 4 min
- **Started:** 2026-03-26T05:58:29Z
- **Completed:** 2026-03-26T06:02:57Z
- **Tasks:** 3
- **Files modified:** 7

## Accomplishments

- Heartbeat Checksum Health section with exception-only pattern (clean = 1 line, failures = per-failure detail)
- JSONL telemetry log capturing all checksum operations from both seeder and sweep
- CRITICAL-tier LOUD persistent Telegram alert on any checksum failure in last 24h
- Seeder wired with verify_pass, verify_fail, verify_retry, verify_skip telemetry
- Sweep wired with sweep_pass, sweep_fail, sweep_skip telemetry at every outcome path

## Task Commits

Each task was committed atomically:

1. **Task 1: Checksum telemetry log module + heartbeat check module** - `2a12cbf` (feat)
2. **Task 2: Formatter checksum section + LOUD alert wiring** - `3c5fd97` (feat)
3. **Task 3: Wire telemetry log into seeder and sweep callers** - `22519d1` (feat)

## Files Created/Modified

- `python/opendeviationbar/checksum_telemetry.py` - Append-only JSONL telemetry log for checksum ops
- `scripts/heartbeat/checks/checksum.py` - Heartbeat check module reading registry + JSONL
- `scripts/heartbeat/checks/__init__.py` - Wired check_checksum into run_checks()
- `scripts/heartbeat/config.py` - Added checksum_ok to CRITICAL_KEYS
- `scripts/heartbeat/formatter.py` - Checksum Health section + remediation hint
- `scripts/tick_cache_seeder.py` - log_checksum_event at 4 outcome points
- `scripts/integrity_sweep.py` - log_checksum_event at 7 outcome points

## Decisions Made

- checksum_ok placed in CRITICAL_KEYS (LOUD) rather than WARNING_KEYS (silent) because a checksum failure indicates potentially corrupted data in the cache -- data integrity is critical

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] Fixed ruff PLW2901 lint violation in checksum check module**

- **Found during:** Task 1 commit
- **Issue:** `for line in f: line = line.strip()` triggers PLW2901 (loop variable overwritten)
- **Fix:** Renamed to `raw_line` / `stripped` pattern
- **Files modified:** scripts/heartbeat/checks/checksum.py
- **Committed in:** 2a12cbf (part of Task 1 commit)

---

**Total deviations:** 1 auto-fixed (1 bug/lint)
**Impact on plan:** Cosmetic lint fix, no scope creep.

## Issues Encountered

None

## User Setup Required

None - no external service configuration required.

## Known Stubs

None - all data flows are wired to real sources (ChecksumRegistry, JSONL telemetry log).

## Next Phase Readiness

- Checksum verification monitoring is fully wired into the heartbeat pipeline
- v6.0 Data Integrity milestone is complete: Phases 8-12 all shipped
- Seeder and sweep both emit JSONL telemetry for post-mortem analysis

---

_Phase: 12-telemetry-heartbeat_
_Completed: 2026-03-26_
