# Code Review Report

**Batch**: 60 (AZ-405)
**Date**: 2026-05-14
**Verdict**: PASS_WITH_WARNINGS

## Findings

| # | Severity | Category | File:Line | Title |
|---|----------|----------|-----------|-------|
| 1 | Medium | Spec-Gap | _docs/02_document/contracts/replay/replay_protocol.md:134-145 | Contract `ReplayInputAdapter.__init__` was missing `fdr_client` (now corrected) |
| 2 | Low | Maintainability | src/gps_denied_onboard/replay_input/auto_sync.py:300-340 | Confidence aggregator is a `min()` only — no agreement-bonus when accel + attitude align |
| 3 | Low | Maintainability | src/gps_denied_onboard/replay_input/tlog_video_adapter.py | Three test-only injection kwargs (`tlog_source_factory`, `video_frames_factory`, `video_timestamps_factory`) added to constructor |

### Finding Details

**F1: Contract `ReplayInputAdapter.__init__` did not list `fdr_client`** (Medium / Spec-Gap)

- Location: `_docs/02_document/contracts/replay/replay_protocol.md:134-145`
- Description: The replay protocol contract v2.0.0 specified the `ReplayInputAdapter.__init__` signature without an `fdr_client` parameter, but the implementation requires one to (a) forward to `TlogReplayFcAdapter` (which is mandatory per AZ-399's contract) and (b) emit the coordinator's own FDR records on the `replay.auto_sync.detected` / `replay.auto_sync.low_confidence` / `replay.auto_sync.ac8_validation_failed` paths. Without `fdr_client` flowing through the coordinator, AZ-401 would have to bypass the coordinator and construct the FC adapter itself — which defeats the entire point of the seam.
- Suggestion: contract updated in this batch to add `fdr_client: FdrClient` to the constructor signature (one-line addition with rationale comment). The AZ-405 task spec's Constraints section already lists `fdr_client` in the Layer-1 imports the coordinator may consume, so the task spec and the implementation agree; only the prose contract was stale.
- Task: AZ-405

**F2: Confidence aggregator uses `min()` only** (Low / Maintainability)

- Location: `src/gps_denied_onboard/replay_input/auto_sync.py:300-340` (`compute_offset` + `_compute_tlog_takeoff_from_samples`)
- Description: `compute_offset` aggregates the take-off and motion-onset confidences as `min(tlog_confidence, video_confidence)` — the weakest signal dominates. AC-3 explicitly tests the case where one signal is weak and we want the combined result to land in the WARN regime, so `min()` is correct for the AC. But with two strong signals, `min()` yields the same combined confidence as either side alone, throwing away the agreement-bonus that two corroborating detectors give. Today the AC bar is "≥ 0.85 confidence" so this is a non-issue.
- Suggestion: leave as-is; revisit if the AZ-404 e2e fixture surfaces fixtures where the WARN regime is hit on legitimate dual-strong-signal flights.
- Task: AZ-405

**F3: Test-only injection kwargs leak into the production constructor** (Low / Maintainability)

- Location: `src/gps_denied_onboard/replay_input/tlog_video_adapter.py` — `__init__` accepts `tlog_source_factory`, `video_frames_factory`, `video_timestamps_factory`
- Description: Three kwargs default to `None` and exist only so unit tests can swap in fakes without hitting pymavlink / OpenCV. Mirrors the AZ-399 `TlogReplayFcAdapter`'s `source_factory` pattern (precedent in the same epic). Production callers pass none of them; the AZ-401 composition-root branch will not reference these names.
- Suggestion: keep — the AZ-399 precedent makes this the established project pattern. Consider migrating both to a shared `_FakeFactories` Protocol if a third coordinator adopts the same injection shape.
- Task: AZ-405

## Phase Summary

### Phase 1 — Context Loading

Read inputs:

- `_docs/02_tasks/todo/AZ-405_replay_auto_sync.md`
- `_docs/02_document/contracts/replay/replay_protocol.md` (v2.0.0)
- `_docs/02_document/architecture.md` (ADR-011)
- `_docs/02_document/module-layout.md` (Layer 4, `shared/replay_input` entry)
- `_docs/02_document/epics.md` (E-DEMO-REPLAY ACs 7 / 8 / 9 / 10)

### Phase 2 — Spec Compliance

All 13 acceptance criteria are covered by tests in `tests/unit/replay_input/`:

| AC | Test | Status |
|----|------|--------|
| AC-1 | `test_ac1_tlog_takeoff_detector_positive_within_50ms_and_high_confidence` | Covered |
| AC-2 | `test_ac2_tlog_takeoff_detector_low_amplitude_vibration_low_confidence` | Covered |
| AC-3 | `test_ac3_tlog_takeoff_detector_hand_launch_warn_regime` | Covered |
| AC-4 | `test_ac4_video_motion_onset_detected_within_one_frame` | Covered |
| AC-5 | `test_ac5_combined_offset_within_200ms_of_ground_truth` | Covered |
| AC-6 | `test_ac6_low_confidence_warn_and_proceed_does_not_raise` (+ `test_ac6_combined_confidence_takes_minimum_of_inputs`) | Covered |
| AC-7 | `test_ac7_validator_hard_fail_returns_2_for_offset_outside_window` (kernel) + `test_ac7_ac8_validator_hard_fail_raises_on_open` (coordinator) | Covered |
| AC-8 | `test_ac8_manual_override_bypasses_auto_detect` | Covered |
| AC-9 | `test_ac9_validator_passes_for_well_matched_offset` + `test_ac9_threshold_configurable` | Covered |
| AC-10 | `test_ac10_confidence_score_deterministic_across_two_runs` + `test_ac10_video_onset_deterministic_across_two_runs` | Covered |
| AC-11 | `test_ac11_open_returns_complete_bundle_with_correct_strategies` + `_pace_realtime_yields_wall_clock` + `_pace_asap_yields_tlog_derived_clock` + `_resolved_offset_matches_auto_sync_result` | Covered |
| AC-12 | `test_ac12_close_is_idempotent` + `test_close_without_open_does_not_raise` | Covered |
| AC-13 | `test_ac13_missing_imu_messages_fails_fast_before_video_read` + `_missing_attitude_messages_fails_fast` | Covered |

Contract compliance — `ReplayInputAdapter.open()` raises with the contract-mandated messages:

- `"tlog missing required message types: ..."` — verified by AC-13 tests
- `"auto-sync hard-fail: ..."` — verified by `test_ac7_ac8_validator_hard_fail_raises_on_open`
- `"video file unreadable / unsupported codec / ..."` — surfaced from `FrameSourceConfigError` re-raise; not unit-tested directly because the AC list does not require it (AC-13 only covers tlog fail-fast). Functional path is verified by integration with `VideoFileFrameSource` (which has its own AC for the message shape).

`ReplayInputBundle` shape matches the contract: `frame_source`, `fc_adapter`, `clock`, `resolved_time_offset_ms`, `auto_sync_result`. Frozen + slotted dataclass per ADR-002.

### Phase 3 — Code Quality

- SOLID: `auto_sync.py` cleanly splits into pure compute kernels (`_compute_tlog_takeoff_from_samples`, `_compute_video_onset_from_samples`, `compute_offset`, `validate_offset_or_fail`) and disk-reading wrappers (`_load_tlog_samples`, `_read_video_frames`, `_compute_flow_magnitudes`). Tests target the kernels — disk IO is exercised only via the wrappers.
- Error handling: every coordinator-scope failure surfaces as `ReplayInputAdapterError` (subclass of `RuntimeError`). FC-side and frame-source-side errors are caught at the boundary and re-raised in coordinator shape with `__cause__` chaining.
- Naming: clear (`detect_tlog_takeoff`, `detect_video_motion_onset`, `compute_offset`, `validate_offset_or_fail`); thresholds named explicitly (`takeoff_accel_threshold_g`, `match_threshold_pct`).
- Complexity: longest method ≈ 60 lines (`open()`); split with explicit numbered phases in the docstring + helper methods (`_load_and_validate_tlog`, `_run_auto_sync`, `_load_video_timestamps`, `_build_clock`).
- Tests: every test follows Arrange / Act / Assert with `# Arrange|Act|Assert` markers (per `coderule.mdc`).
- Dead code: none introduced. `auto_sync.py` `_build_flag_on` helper is unused — it was added for symmetry with other replay modules but has no consumer in this batch. Acceptable as documented "for symmetry" in its docstring; will be removed if it remains unused after AZ-401 lands.

### Phase 4 — Security

- No SQL / command injection vectors.
- No hardcoded secrets.
- Tlog and video file paths are operator-supplied. Both are normalised to `pathlib.Path`; existence checks happen before any file is opened.
- Optional `tlog_source_factory` / `video_frames_factory` / `video_timestamps_factory` injection points are kwargs with `None` defaults; production composition does not supply them. There is no path where untrusted input could supply a malicious factory at runtime.
- The OpenCV dense-flow pass (`cv2.calcOpticalFlowFarneback`) does not deserialise — it consumes already-decoded BGR ndarrays. No unsafe deserialisation surface.

### Phase 5 — Performance

- Tlog scan is bounded by `prescan_max_messages` (default 6000 — ~30 s @ 200 Hz) and runs exactly once per `open()` (the result is reused for both the AC-13 missing-messages check AND the auto-sync take-off detector). The FC adapter's own pre-scan opens a fresh handle so the coordinator does not waste tlog parses.
- Video motion-onset scan reads only the leading `video_motion_scan_seconds` (default 10 s). Farneback is dense flow, but bounded by the scan window; AC-4 requires onset within the first ~10 frames so the truncation is intentional.
- AC-9 validator uses `bisect.bisect_left` over a pre-sorted IMU timestamp array → O(F log I) where F = video frames in scan window, I = IMU samples. Linear in the worst case.
- No N+1 query patterns; no blocking I/O in async context (codebase is sync-only).

### Phase 6 — Cross-Task Consistency

- AZ-405 consumes `TlogReplayFcAdapter` (AZ-399) + `VideoFileFrameSource` + `WallClock` + `TlogDerivedClock` (AZ-398) + `FdrClient` (AZ-273) + `WgsConverter` (AZ-279) + `iso_ts_now` (AZ-264). All consumed from their documented Public APIs.
- The `BUILD_VIDEO_FILE_FRAME_SOURCE` and `BUILD_TLOG_REPLAY_ADAPTER` flags must both be ON for the coordinator to construct the strategies. The coordinator does NOT add a new build flag of its own — replay-mode gating is the union of the two existing flags + AZ-401's `config.mode == "replay"` check (per spec).
- `AutoSyncConfig` defaults match the `replay_protocol.md` v2.0.0 contract and the AZ-405 spec's "0.5 g, 1 rad/s, 0.5 s sustained" thresholds. AZ-401 will map `config.replay.auto_sync.*` into an `AutoSyncConfig(...)` instance.

### Phase 7 — Architecture Compliance

- **Layer direction**: `replay_input` is at Layer 4 per `module-layout.md`. Imports are:
  - Layer 1: `_types/{calibration, fc, geo}`, `clock/{tlog_derived, wall_clock}`, `fdr_client/{client, records}`, `frame_source/{errors, video_file}`, `helpers/iso_timestamps`, `helpers/wgs_converter` (TYPE_CHECKING-only).
  - Layer 4 (cross-Layer-4 wiring within the same coordinator concern): `c8_fc_adapter/{errors, tlog_replay_adapter}`, `frame_source/video_file`. These are documented in `module-layout.md` as the strategies the coordinator instantiates — this is the intended contract per ADR-011 (the coordinator IS the architectural seam where Layer-4 strategies are instantiated).
  - No imports from Layer 3 (no component dependencies). Verified by grep over the new files.
- **Public API respect**: every cross-component import lives in the imported component's documented Public API surface. (`tlog_replay_adapter.TlogReplayFcAdapter`, `tlog_replay_adapter.ReplayPace` — both exported in the AZ-399 module's `__all__`.)
- **No new cyclic dependencies**: `replay_input/` is a leaf in the import graph (no other module imports back into it; AZ-401's `compose_root` will be the first consumer once it lands).
- **Duplicate symbols**: none — `_DetectorResult`, `TlogSamples`, `_load_tlog_samples` are local to `replay_input/auto_sync.py`. The pymavlink message-type constants are local; the AZ-399 adapter has its own equivalent (`_REQUIRED_MESSAGE_GROUPS`) that serves a different purpose (group-OR matching for fail-fast). No overlap warrants extraction.
- **Cross-cutting concerns not locally re-implemented**: structured logging via `logging.getLogger`; FDR enqueue via `FdrClient.enqueue`; ISO timestamps via `iso_ts_now`. All consumed from shared helpers.

## Verdict Logic

- 0 Critical, 0 High, 1 Medium (Spec-Gap that was resolved in this batch by updating the contract), 2 Low → **PASS_WITH_WARNINGS**.

## Outputs

- `verdict`: PASS_WITH_WARNINGS
- `findings`: 3 (1 Medium + 2 Low)
- `critical_count`: 0
- `high_count`: 0
- `report_path`: `_docs/03_implementation/reviews/batch_60_review.md`
