---
phase: 09-verification-registry
plan: 01
subsystem: storage
tags: [checksum, sha256, verification, json, registry]

# Dependency graph
requires:
  - phase: 08-checksum-spike
    provides: Rust SHA-256 checksum bindings validated from Python
provides:
  - ChecksumRegistry class with add/query/persist API
  - VerificationRecord dataclass for per-file verification state
affects: [10-seeder-wire, 11-sweep, 12-heartbeat-wire]

# Tech tracking
tech-stack:
  added: []
  patterns: [atomic-json-persistence, upsert-keyed-dict]

key-files:
  created:
    - python/opendeviationbar/checksum_registry.py
    - tests/test_checksum_registry.py
  modified: []

key-decisions:
  - "Keyed by {symbol}:{date} string for O(1) upsert and lookup"
  - "No auto-save on add() -- callers batch writes then call save() for efficiency"
  - "Atomic write via tmp+Path.replace pattern (same as TickStorage)"

patterns-established:
  - "Registry pattern: JSON state file with version field, auto-load in __init__, atomic save"
  - "Upsert dict: single key per logical entity prevents duplicates without explicit dedup"

requirements-completed: [TELEM-03]

# Metrics
duration: 3min
completed: 2026-03-26
---

# Phase 09 Plan 01: Verification Registry Summary

**ChecksumRegistry with per-file SHA-256 verification state, upsert dict storage, and atomic JSON persistence**

## Performance

- **Duration:** 3 min
- **Started:** 2026-03-26T05:18:20Z
- **Completed:** 2026-03-26T05:21:30Z
- **Tasks:** 1 (TDD: RED + GREEN)
- **Files modified:** 2

## Accomplishments

- VerificationRecord dataclass with symbol, date, sha256, verified_at, source fields
- ChecksumRegistry with full CRUD: add, has_verified, query_by_symbol, query_by_date_range, summary
- Atomic JSON persistence with tmp+replace pattern, tolerant of missing/corrupt files
- 17 unit tests covering all 11 behaviors + 4 edge cases

## Task Commits

Each task was committed atomically:

1. **Task 1 (RED): Failing tests** - `8b85e92` (test)
2. **Task 1 (GREEN): ChecksumRegistry implementation** - `a35e432` (feat)

_TDD task: test-first then implementation._

## Files Created/Modified

- `python/opendeviationbar/checksum_registry.py` - ChecksumRegistry class + VerificationRecord dataclass (161 lines)
- `tests/test_checksum_registry.py` - 17 unit tests covering full API (239 lines)

## Decisions Made

- Keyed by `{symbol}:{date}` string for O(1) upsert and lookup -- simplest correct approach
- No auto-save on `add()` -- callers batch writes then call `save()` for seeder efficiency (many adds per session)
- Atomic write via `tmp+Path.replace` pattern consistent with TickStorage conventions
- `load()` in `__init__` auto-loads existing state so registry is always current on creation
- Standard library only (json, dataclasses, pathlib, datetime, logging) -- no new dependencies

## Deviations from Plan

None - plan executed exactly as written.

## Known Stubs

None - all API methods are fully implemented with real logic.

## Issues Encountered

None.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- ChecksumRegistry is ready for Phase 10 (seeder writes records after verification)
- ChecksumRegistry is ready for Phase 11 (sweep reads `has_verified()` to skip already-verified files)
- ChecksumRegistry is ready for Phase 12 (heartbeat calls `summary()` for telemetry)

---

_Phase: 09-verification-registry_
_Completed: 2026-03-26_
