## Review 001: Focus session and break timer implementation — M6 bugfix review

**Files reviewed:** frontend/src/App.tsx, frontend/src/FocusTimer.tsx, frontend/src/api.ts, src/backend/api/__init__.py, src/backend/api/messages.py, src/backend/api/sessions.py, src/backend/api/settings.py, src/backend/models.py
**Verdict:** request-changes

### Findings

#### block: Orphaned test file references deleted endpoint
**Location:** tests/test_messages.py (entire file)
**Quote:**

```
def test_post_and_list_messages(client):
    res = client.post("/api/messages", json={"text": "hello"})
    assert res.status_code == 200
```

**Read:** This test file exercises POST /api/messages and GET /api/messages endpoints. Those endpoints no longer exist (src/backend/api/messages.py is now empty, and the router is unregistered from api/__init__.py). When pytest attempts to run these tests, they will fail with 404s or connection errors.
**Concern:** The skeleton template's cleanup instructions (visible in the now-empty messages.py docstring and in __init__.py) explicitly require deletion of tests/test_messages.py when messages.py is removed. This file blocks test collection and hides signal from the actual feature tests (test_focus_session_with_visual_countdown, test_break_timer_*, test_daily_review_*). Per the template: 'Leaving this file when messages.py is gone causes a collection failure that hides all your real test signal.' That is exactly the current state.
**Request:** Delete tests/test_messages.py entirely. The skeleton cleanup is documented in two places that the implementation passed — it should have been followed.

#### note: Cleanup task completed: messages.py emptied
**Location:** src/backend/api/messages.py
**Quote:**

```
[file is empty]
```

**Read:** The placeholder messages.py endpoint implementation has been removed. The file itself remains (empty) but is no longer imported by src/backend/api/__init__.py.
**Concern:** Per the skeleton template, this file should be fully deleted, not left empty. An empty file is an artifact of incomplete deletion and signals unfinished work.
**Request:** Fully delete src/backend/api/messages.py (not just empty it). This completes the skeleton cleanup as documented.

### Approvals

- Bug #1 resolved correctly: TimerState now includes 'completing' at line 25 in FocusTimer.tsx. This resolves the TypeScript compilation error. The state machine is now complete.
- Bug #2 resolved correctly: after persisting SessionLog in the POST /sessions/log handler (lines 184–205 in sessions.py), the code queries for and updates the in-progress Session record to COMPLETED status. This ensures session queries return correct status and prevents stale state. The logic is sound and accounts for both focus and break session types.
- Session logging contract is well-specified: SessionLogRequest includes duration validation (actual <= configured + 5% drift tolerance) and completed_at validation (ISO8601, not in future). SessionLogResponse confirms acknowledgment. This establishes clear boundaries between client and server.
- Break session auto-creation on focus completion is appropriately implemented (lines 253–270 in sessions.py). The code uses a configurable default (300s) with room to read from user settings in the future. Defaults are reasonable.
- FocusTimer component is well-structured: separate concerns for elapsed/remaining time tracking (refs + interval loop), state machine with defined transitions (idle → running → paused → completing → completed), and user-facing error messaging. The progress bar and state indicator keep the UX clear.
- Session API is comprehensive: POST /sessions/log (logging), GET /sessions (daily history), POST /sessions/break (manual break creation), PATCH /sessions/{id} (pause/resume/skip actions), DELETE /sessions/{id} (skip/cancel). This provides the surface area needed for the feature set.

### Cross-domain references

- No architectural concerns; the three-endpoint pattern (sessions, settings, health) is consistent with the proposed structure.
- No test scenario gaps identified; the shipped tests (test_focus_session_with_visual_countdown, test_break_timer_*, test_daily_review_*) cover the feature breadth. The Hatter will use these as a baseline for edge-case scenarios.
- UserSettings model is a backend stub (not used in session logic) per v1 contract. Client-side localStorage is primary. This is correct and documented in the model docstring.
