# Review by Principal Systems Engineer (Google/Stripe caliber) (Round 1)

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

VERDICT: **approve** ✅

All 8 functional requirements (FR-1 through FR-8) are implemented and verified. 316 tests pass. The diff is tightly scoped: ~42 lines of production code across 4 files, backed by 612 lines of tests across 3 files.

**Key observations:**

1. **Dedup is rock-solid** — The dual-event delivery race (Slack fires both `app_mention` and `message` for the same @mention) is correctly handled by the existing `_pending_messages` + `is_processed()` infrastructure, verified by 3 dedicated race-condition tests.

2. **👀 lifecycle is correct** — Mentions get immediate 👀 (expected acknowledgment). Passive messages get 👀 only after triage confirms actionable (invisible until relevant). Non-actionable passive messages never get a reaction. This avoids the "creepy bot" problem.

3. **Blast radius is minimal** — 2 lines in `register()`, a function swap + conditional in `_handle_event`, 4 lines for post-triage reaction, and a static startup warning method. No changes to `should_process_message()` or any existing filter logic.

**Two minor non-blocking findings for follow-up:**
- Triage-queue-full warning message leaks to passive messages (reveals the bot was listening)
- `extract_prompt_text` uses `text.strip()` for passive messages vs. `extract_prompt_from_mention`'s richer sanitization — worth auditing the delta

Review artifact written to `cOS_reviews/reviews/principal_systems_engineer_google_stripe_caliber/20260401_140000_round1_...md`.