# Staff Security Engineer — Review Round 1

**Branch:** `colonyos/when_you_output_followups_in_the_thread_on_slack_a938599349`
**PRD:** `cOS_prds/20260331_190640_prd_you_are_a_code_assistant_working_on_behalf_of_the_engineering_team_the_following.md`

## Checklist

### Completeness
- [x] All functional requirements from the PRD are implemented (FR-1 through FR-5)
- [x] All tasks in the task file are marked complete (1.0–6.0)
- [x] No placeholder or TODO code remains

### Quality
- [x] All 121 tests pass (test_sanitize.py + test_slack_formatting.py)
- [x] Code follows existing project conventions
- [x] No unnecessary dependencies added
- [x] No unrelated changes included

### Safety
- [x] No secrets or credentials in committed code
- [x] No destructive database operations
- [x] Error handling present for failure cases (try/except on cost/duration parsing, empty-string guards, fallback paths)

---

VERDICT: approve

FINDINGS:
- [src/colonyos/sanitize.py:88-89]: Minor gap — `_SLACK_LINK_INJECTION_RE` only matches `http`/`https` links. Slack also supports `<mailto:user@corp.com|click>` and `<slack://open?team=T123|text>` link patterns that could be used for phishing. Low severity since the bare-link regex on line 108 catches `<https://...>` but non-http schemes slip through both regexes. Recommend expanding to `<[^>|]+\|[^>]+>` in a follow-up.
- [src/colonyos/sanitize.py:83-85]: `_SLACK_MENTION_RE` does not cover `<@U12345>` user-mention injection. A malicious description could include `<@U12345>` to ping specific users. Low severity — Slack requires valid user IDs and the XML sanitizer strips angle-bracket tags, so exploitation requires a real user ID that survives `sanitize_untrusted_content()`.
- [src/colonyos/orchestrator.py:875]: Correct double-sanitization applied: `sanitize_untrusted_content()` first (strip XML injection), then `sanitize_for_slack()` (escape mrkdwn). This ordering is correct and consistently applied at all 7 call sites.
- [src/colonyos/orchestrator.py:1540-1568]: `_extract_review_findings_summary()` correctly sanitizes each extracted finding before returning it. This prevents review text that echoes secrets from source code (e.g., hardcoded API keys in findings like `[src/config.py]: API_KEY = "sk-..."`) from being rendered raw in Slack.
- [tests/test_slack_formatting.py]: 588 lines of comprehensive tests including sanitization integration tests (class `TestSanitizationIntegration`) that verify mrkdwn escaping and XML stripping flow through the formatting functions end-to-end. Good coverage.
- [src/colonyos/orchestrator.py:1318-1332]: `_truncate_slack_message()` correctly caps at 3,000 chars and is applied at all 4 `slack_note()` call sites (lines 4561, 4586, 4620, 4773). The 3,000-char cap is well under Slack's 40,000 limit and provides defense-in-depth against information leakage from oversized review texts.

SYNTHESIS:
From a security perspective, this is a well-executed implementation. The critical requirement — FR-5 sanitization — is implemented correctly with the right defense-in-depth approach: `sanitize_untrusted_content()` strips XML-like tags first, then `sanitize_for_slack()` escapes mrkdwn metacharacters and neutralizes mention/link injection. This double-pass is applied consistently at all 7 points where untrusted content enters the formatting pipeline. The truncation layer (`_truncate_slack_message()`) provides a secondary control against information leakage from verbose review findings. The two gaps I identified (non-http link schemes and `<@U>` user mention patterns) are both low severity: the XML sanitizer already strips most angle-bracket patterns, and exploitation would require crafting content that survives both sanitization passes. These are worth tracking for a hardening follow-up but are not blocking. Tests are thorough, including dedicated integration tests that verify the sanitization chain works end-to-end through the formatting functions. Approving.
