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

## Review Complete

**VERDICT: approve**

All 5 functional requirements are implemented correctly across 9 commits (+1,300/-23 lines). 131 tests pass. The implementation is clean, well-scoped, and architecturally sound.

**Key strengths:**
- Pure formatting functions with zero I/O — impossible to cause a 3am incident
- Double-sanitization (`sanitize_untrusted_content()` → `sanitize_for_slack()`) at every untrusted content ingress point
- 3-tier fallback for review finding extraction (FINDINGS → SYNTHESIS → first line) handles real-world LLM output variance
- Named constants replace all magic numbers; truncation is intrinsic to formatters
- Blast radius is minimal — worst case is ugly Slack messages, not lost pipeline state

**Non-blocking findings:**
1. `_SLACK_BARE_LINK_RE` only strips bare `http(s)://` links — bare `mailto:`/`slack://` without display text not covered (low risk)
2. FR-1 phase header truncates at 60 chars vs PRD's specified 72 (cosmetic)
3. With many reviewers, `_truncate_slack_message` could drop entire reviewer entries without indication (unlikely with typical 4-5 reviewers)
4. Vestigial `try/except ImportError` guard in test file from incremental development

Review artifact saved to `cOS_reviews/reviews/principal_systems_engineer_google_stripe_caliber/20260331_200000_round1_when_you_output_followups_in_the_thread_on_slack_a938599349.md`.
