---
phase: 04-heartbeat-coverage
plan: 01
subsystem: monitoring
tags: [heartbeat, symbol-registry, telegram, yesterday-completion]

# Dependency graph
requires:
  - phase: 01-crossover-tid-utility
    provides: get_crossover_tid() shared utility used by yesterday.py
provides:
  - get_heartbeat_symbols() dynamic Binance spot symbol lookup from registry
  - Yesterday completion check expanded from 2 to all 17+ streaming symbols
affects: [05-documentation]

# Tech tracking
tech-stack:
  added: []
  patterns:
    [
      lru_cache for registry-backed config,
      graceful fallback on registry failure,
    ]

key-files:
  created: []
  modified:
    - scripts/heartbeat/config.py
    - scripts/heartbeat/checks/yesterday.py
    - tests/test_heartbeat_yesterday_junction.py

key-decisions:
  - "lru_cache(maxsize=1) for get_heartbeat_symbols -- heartbeat is a 5-min oneshot, no stale-cache risk"
  - "Fallback to (BTCUSDT, ETHUSDT) on any exception, not just ImportError -- heartbeat must never crash"
  - "Keep HEARTBEAT_PRIORITY_SYMBOLS constant for backward compat (freshness.py uses it for display ordering)"

patterns-established:
  - "Registry-backed config: lazy import + try/except + fallback constant for heartbeat modules"

requirements-completed: [HB-01]

# Metrics
duration: 5min
completed: 2026-03-25
---

# Phase 4 Plan 1: Dynamic Heartbeat Symbol Coverage Summary

**Yesterday completion check expanded from 2 hardcoded symbols to all enabled Binance spot symbols via registry lookup with graceful fallback**

## Performance

- **Duration:** 5 min
- **Started:** 2026-03-25T08:28:23Z
- **Completed:** 2026-03-25T08:33:44Z
- **Tasks:** 1 (TDD: RED + GREEN)
- **Files modified:** 3

## Accomplishments

- `get_heartbeat_symbols()` dynamically queries symbol registry for all enabled Binance spot symbols
- Exness forex symbols correctly excluded (no agg_trade_id)
- Graceful fallback to (BTCUSDT, ETHUSDT) on registry failure -- heartbeat never crashes
- Multi-symbol aggregation: `yesterday_completion=False` if ANY symbol has a mismatch
- 13 tests covering filtering, fallback, multi-symbol aggregation, and existing behavior

## Task Commits

Each task was committed atomically (TDD):

1. **Task 1 RED: Failing tests for dynamic symbol lookup** - `15364d5` (test)
2. **Task 1 GREEN: Implement get_heartbeat_symbols + rewire yesterday.py** - `a1de47e` (feat)

## Files Created/Modified

- `scripts/heartbeat/config.py` - Added `get_heartbeat_symbols()` with `lru_cache`, Binance spot filter, fallback
- `scripts/heartbeat/checks/yesterday.py` - Replaced `HEARTBEAT_PRIORITY_SYMBOLS` import with `get_heartbeat_symbols`
- `tests/test_heartbeat_yesterday_junction.py` - 5 new tests for get_heartbeat_symbols, 2 new multi-symbol tests, updated 4 existing tests

## Decisions Made

- Used `lru_cache(maxsize=1)` since heartbeat runs as fresh systemd oneshot every 5 minutes
- Kept `HEARTBEAT_PRIORITY_SYMBOLS` with deprecation comment for backward compat (freshness.py display ordering)
- Used `logging.getLogger("health-heartbeat")` inline per plan instruction (no module-level logger)

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Phase 4 complete, ready for Phase 5 (Documentation)
- All heartbeat monitoring now covers full Binance spot symbol set

---

_Phase: 04-heartbeat-coverage_
_Completed: 2026-03-25_
