# Review: Informative Slack Pipeline Notifications

**Reviewer:** Principal Systems Engineer (Google/Stripe caliber)
**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`
**Round:** 1

## Checklist

### Completeness
- [x] FR-1: Task completion messages include description (phase_header call at line 875)
- [x] FR-2: Task outline uses bullet formatting (`_format_task_outline_note`)
- [x] FR-3: Task result summary includes descriptions with cost/duration (`_format_implement_result_note`)
- [x] FR-4: Review round messages include finding summaries (`_format_review_round_note` + `_extract_review_findings_summary`)
- [x] FR-5: Sanitization with `sanitize_for_slack()` + `sanitize_untrusted_content()` applied to all untrusted content
- [x] FR-5: Truncation via `_truncate_slack_message()` at all call sites
- [x] All 6 task groups marked complete in task file
- [x] No placeholder or TODO code remains

### Quality
- [x] All 2,890 tests pass (including 121 new tests across `test_slack_formatting.py` and `test_sanitize.py`)
- [x] Code follows existing project conventions (private functions with `_` prefix, docstrings, type hints)
- [x] No unnecessary dependencies added (pure string operations + re)
- [x] No unrelated changes included (6 files changed, all on-topic)

### Safety
- [x] No secrets or credentials in committed code
- [x] `sanitize_for_slack()` neutralizes @here/@channel/@everyone mention injection
- [x] `sanitize_for_slack()` neutralizes `<url|text>` link injection (phishing vector)
- [x] `sanitize_for_slack()` escapes mrkdwn metacharacters (`*`, `_`, `~`, `` ` ``)
- [x] `sanitize_for_slack()` neutralizes blockquote injection (`>` at line start)
- [x] XML tag stripping via `sanitize_untrusted_content()` applied before Slack sanitization
- [x] Error handling present in cost/duration formatting (try/except for ValueError/TypeError)

---

VERDICT: approve

FINDINGS:
- [src/colonyos/orchestrator.py:1340]: `_truncate_slack_message` truncates at 3,000 chars but is only applied at call sites, not inside the individual formatting functions. If a future caller uses `_format_review_round_note()` without wrapping in `_truncate_slack_message()`, the cap won't apply. Low risk since all current call sites are wrapped, but consider making the truncation intrinsic to each formatter in a future cleanup.
- [src/colonyos/orchestrator.py:1510-1553]: `_extract_review_findings_summary` has a clean 3-tier fallback (FINDINGS → SYNTHESIS → first line). One edge case: if FINDINGS section has blank lines between items (some LLM outputs do this), the parser stops collecting at the blank line. This means it might return only 1 finding when 2 exist. Acceptable for v1 since partial findings are better than none.
- [tests/test_slack_formatting.py:420-438]: `TestMessageSizeCap.test_implement_result_max_length` correctly generates pathological input (50 tasks × 100-char descriptions) but the assertion is `len(result) > 0` rather than `len(result) <= 3000`. This is because `_truncate_slack_message` is applied at call sites, not inside `_format_implement_result_note`. The test validates the function doesn't crash but doesn't assert the size cap. The truncation is tested separately in `TestTruncateSlackMessage`, so coverage is adequate but the integration boundary could be tighter.
- [src/colonyos/sanitize.py:95-123]: `sanitize_for_slack()` applies escaping to mrkdwn metacharacters uniformly. This means legitimate formatting in ColonyOS-controlled strings (like `*bold header*`) would also be escaped if accidentally passed through. The current call pattern (only applied to untrusted user/LLM content, not to ColonyOS's own formatting strings) is correct — just needs to stay that way.
- [src/colonyos/orchestrator.py:878]: Description truncation uses 60 chars (57 + "...") for phase_header but 72 chars elsewhere (69 + "..."). Minor inconsistency — phase_header has a tighter budget because it's a single-line header. Acceptable tradeoff.

SYNTHESIS:
This is a clean, well-scoped implementation that does exactly what the PRD asks for — no more, no less. The architectural decision to keep formatting logic in the orchestrator (where the data lives) and sanitization in the sanitize module is correct. The dual-layer sanitization (XML stripping then Slack mrkdwn escaping) properly handles the two threat vectors. The 3-tier fallback in `_extract_review_findings_summary` (FINDINGS → SYNTHESIS → first line) is the right design for parsing semi-structured LLM output — it degrades gracefully rather than producing empty messages. All 2,890 tests pass, the 121 new tests cover the formatting functions thoroughly including sanitization integration tests and pathological input tests. The code is production-ready. The only operational concern is that the 3,000-char truncation is applied at call sites rather than baked into formatters, which creates a maintenance hazard if new call sites are added — but this is a minor future risk, not a shipping blocker.
