# Review by Staff Security Engineer (Round 3)

## Staff Security Engineer — Round 3 Review Summary

**131 tests pass. All 5 functional requirements implemented. Implementation is secure and production-ready.**

### Key Security Assessment

The double-sanitization pattern (`sanitize_untrusted_content()` → `sanitize_for_slack()`) is applied consistently at all 7 untrusted content ingress points in the orchestrator. I verified:

- **Mention injection** — fully covered: `@here`, `@channel`, `@everyone`, `<!here>`, `<!channel|...>`, `<@U...>`, `<@B...>`, `<@W...>`, case-insensitive
- **Link injection** — covered for arbitrary URI schemes with display text (`<scheme://...|text>`) plus bare HTTP/HTTPS links
- **Format injection** — mrkdwn metacharacters (`*`, `_`, `~`, `` ` ``, `>`) all escaped/neutralized
- **Truncation** — 3,000-char cap on all messages, 72-char per description, 80-char per finding

### Non-Blocking Findings

1. `_SLACK_BARE_LINK_RE` only covers `https?://` — bare `<mailto:...>` without display text passes through (low risk, upstream XML sanitizer provides coverage)
2. No audit logging when `sanitize_for_slack()` neutralizes content (would aid injection detection)

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VERDICT: **approve**

Review artifact saved to `cOS_reviews/reviews/staff_security_engineer/20260331_200000_round3_when_you_output_followups_in_the_thread_on_slack_a938599349.md`.
