# Review by Principal Systems Engineer (Google/Stripe caliber) (Round 2)

## Review Complete — Principal Systems Engineer (Round 1)

**377 tests pass, 0 failures.** All 7 functional requirements implemented across ~162 lines of production code in 4 files, with 664 lines of new tests.

VERDICT: approve

FINDINGS:
- [src/colonyos/daemon.py]: Watchdog thread correctly avoids `_agent_lock` by reading only GIL-safe primitives and filesystem stats — architecturally sound
- [src/colonyos/daemon.py]: Dual-condition check (elapsed AND heartbeat age) prevents false positives on long-running but progressing pipelines
- [src/colonyos/daemon.py]: All three pipeline exit paths (success, interrupt, exception) correctly clear `_pipeline_started_at` and `_current_running_item`
- [src/colonyos/daemon.py]: `_post_slack_message()` in `_watchdog_recover` lacks explicit socket timeout — Slack SDK internal timeout (~30s) is the de facto ceiling; non-blocking for v1
- [src/colonyos/daemon.py]: `_pipeline_stalled` flag persists `True` after recovery until next pipeline starts — acceptable but consider clearing on successful completion in v2
- [src/colonyos/daemon.py]: `stall_seconds is None` guard on line ~169 is unreachable (typed int with floor clamp) — harmless defensive code
- [src/colonyos/models.py]: Schema v4→v5 migration is backward-compatible via `None` default on `started_at` — correct
- [tests/test_daemon.py]: 664 lines of thorough tests including failure isolation (Slack errors don't break recovery) and false-positive prevention

SYNTHESIS:
From a systems reliability perspective, this implementation is correct and well-scoped. The fundamental architectural decision — a watchdog thread that's independent of the lock held by the stuck pipeline — is the only design that can work here, and it's executed properly. The dual-condition stall detection (elapsed time AND heartbeat staleness) is the right conservative approach for an auto-recovery system where false positives would be catastrophic. The recovery escalation ladder (graceful → grace period → force → state reset) follows the standard pattern for cooperative cancellation with a hard fallback. The 162 lines of production code are appropriately minimal — no over-engineering, no unnecessary abstractions. The test coverage at ~4:1 ratio with proper emphasis on failure isolation gives me confidence this won't break at 3am. The non-blocking observations (Slack timeout, stale flag persistence, unreachable guard) are all v2 polish items. Ship it.
