# Review by Principal Systems Engineer (Google/Stripe caliber) (Round 3)

Here's my review as **Principal Systems Engineer**:

---

## VERDICT: approve

### Summary

All 10 functional requirements are fully implemented with comprehensive test coverage across Python and TypeScript. No TODOs, no secrets, no placeholder code.

### Key Observations (from a "what happens at 3am" perspective)

**What's excellent:**
- **Fail-closed worktree checks**: The `_preexec_worktree_state` refactor from boolean to tri-state (`clean`/`dirty`/`indeterminate`) is a genuine safety win. The old code silently treated "can't run git" as "worktree is clean." Now it pauses the daemon and records an incident with Slack notification. This is exactly what unattended systems need.
- **Circuit breaker Slack posts moved outside `self._lock`**: Eliminates a real deadlock risk where a Slack timeout could hold the daemon's main lock indefinitely.
- **Notification lock cleanup at all 3 terminal paths**: Prevents unbounded memory growth from `_notification_thread_locks`.
- **Dashboard thread isolation**: `daemon=True` thread with blanket `except Exception` — uvicorn crash cannot take down the daemon.
- **Write-disabled by default** across all config paths, with rate limiting and audit logging on state-changing operations.

**Non-blocking findings (6):**
1. `os.environ.setdefault` is process-global (fine for single-daemon-per-process, worth a comment)
2. No graceful uvicorn shutdown path (daemon thread dies on process exit, dropping in-flight requests)
3. Rate limiter dict has no threading lock (sub-millisecond race window, zero blast radius)
4. `/healthz` and `/api/healthz` both exist — auth only enforced in subdomain mode
5. Health banner swallows fetch errors silently (no distinction between 401 and network error)
6. Deploy docs don't mention ephemeral bearer token lifecycle

None of these are correctness bugs or security vulnerabilities. The full review is at `cOS_reviews/reviews/principal_systems_engineer/round3_review.md`.