# Review by Staff Security Engineer (Round 3)

## Review Complete — Staff Security Engineer

**VERDICT: approve** ✅

### Key findings from a security perspective:

1. **Critical alert routing — verified correct**: All 5 safety-critical paths (`_post_auto_pause_same_error_alert`, `_post_circuit_breaker_escalation_pause_alert`, `_post_circuit_breaker_cooldown_notice`, `_pause_for_pre_execution_blocker`, budget 100% exhaustion) correctly pass `critical=True`, ensuring they post top-level and can never be buried in a daily thread.

2. **Token surface reduced**: The `_post_slack_message` refactoring consolidates token acquisition from 2 independent inline `os.environ.get` + `WebClient()` paths down to 1 via `_get_notification_client()`. Fewer places to audit = better.

3. **Previous round fixes confirmed**: Budget exhaustion alert now fires `critical=True`. Rotation audit trail now logs previous `daily_thread_ts` before overwriting.

4. **State persistence is safe**: All 3 new `DaemonState` fields are daemon-controlled values (Slack API responses, `datetime.now()`). No user input reaches these fields.

5. **Config validation is defensive**: Invalid mode raises, invalid hour raises, invalid timezone falls back to UTC with a warning. No injection vectors.

**One advisory (non-blocking)**: `format_daily_summary` interpolates user-controlled fields into Slack mrkdwn without sanitization — but this is a pre-existing pattern across all `slack.py` formatters, not a regression. Recommend a follow-up `_sanitize_mrkdwn()` utility.

Review artifact written to `cOS_reviews/reviews/staff_security_engineer/20260401_round3_you_are_sending_too_many_slack_messages_to_the_m_1b324759d9.md`.