# Review by Principal Systems Engineer (Google/Stripe caliber) (Round 4)

## Review Complete — Principal Systems Engineer, Round 1

**VERDICT: approve**

### Summary

All 9 functional requirements from the PRD are fully implemented. All 3,110 tests pass (79 new, zero regressions). The implementation is clean and follows every established codebase pattern.

**Key strengths:**
- **Hard-block invariant**: `_fail_run_log()` + `return log` makes it impossible to reach Deliver after persistent test failures — the core safety property holds
- **Correct loop control**: N+1 verify checks for N fix attempts, with dual budget guards before every agent invocation
- **Robust sentinel parsing**: Two-tier `VERIFY_RESULT: PASS/FAIL` sentinel with regex fallback avoids false positives (16 edge-case tests)
- **Audit separation**: Read-only verify and write-enabled fix produce separate `PhaseResult` entries with distinct session IDs
- **Resume chain**: `_compute_next_phase` and `_SKIP_MAP` correctly route `decision→verify→deliver` and `learn→verify`

**Non-blocking observations (all acceptable for v1):**
1. No haiku default for verify model (configurable via `phase_models.verify: haiku`)
2. `Phase.FIX` reused for verify-fix (phase ordering disambiguates in logs)
3. Fail-open on ambiguous output (sentinel contract makes this a narrow gap)

FINDINGS:
- [src/colonyos/orchestrator.py]: Verify-fix loop, sentinel parsing, and hard-block all correctly implemented
- [src/colonyos/config.py]: VerifyConfig with validation and roundtrip follows existing patterns
- [src/colonyos/instructions/verify.md]: Read-only contract with structured sentinel output
- [tests/]: 79 new tests, 3,110 total passing

SYNTHESIS:
Ship it. The implementation is correct, complete, and follows established patterns without introducing unnecessary complexity. The critical safety invariant (never open a broken PR) is enforced and well-tested.
