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

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## Review Complete — Principal Systems Engineer (Google/Stripe caliber)

**Branch:** `colonyos/recovery-7cc0851d44`

VERDICT: **approve** ✅

FINDINGS:
- **[src/colonyos/daemon/_helpers.py]**: Beyond PRD scope (PRD specified 3 submodules, implementation has 4). Acceptable — further reduces `__init__.py` to 1,975 lines vs. the ~2,100 target. Follows identical mixin pattern.
- **[src/colonyos/daemon/_watchdog.py]**: `_get_daemon_module()` lazy import is the correct engineering decision for preserving `patch("colonyos.daemon.request_active_phase_cancel")` test targets. Well-documented with call-site comments.
- **[src/colonyos/daemon/__init__.py]**: MRO `Daemon(_WatchdogMixin, _ResilienceMixin, _HelpersMixin)` is clean — no diamond inheritance, no `__init__` conflicts, no `super()` chain issues.
- **[tests/test_daemon.py]**: Zero modifications. 3 `TestDailyThreadLifecycle` rotation failures confirmed pre-existing on `main` via checkout-and-run.

SYNTHESIS:
This is operationally invisible refactoring — exactly what you want from a structural change to a critical daemon. After 6 failed attempts that broke mock targets, introduced circular imports, or changed public API, attempt 7 does the boring, correct thing: mixins that keep methods on `self`. The `_get_daemon_module()` pattern in the watchdog is a clean solution to the "test patches a module-level name but the mixin imports it directly" problem. Logger namespaces are actually *improved* (per-submodule filtering via `__name__`). The commit history is clean, incremental (6 commits), and individually revertable. 149/152 tests pass; 3 failures are pre-existing on `main` (verified by checking out `main` and running the same tests). No regressions, no new runtime codepaths beyond a lazy import, no changes to tests or CLI. Ship it.

Review artifact written to `cOS_reviews/reviews/principal_systems_engineer_google_stripe_caliber/20260402_064500_round4_colonyos_daemon_py_recovery_context_previous_branch_colonyos_colonyos_daemon_py.md`.
