# Review by Staff Security Engineer (Round 2)

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## Staff Security Engineer — Review Summary

**VERDICT: approve**

### Key Security Findings

**Positive (things done right):**
- ✅ **Triage agent has zero tool access** (`allowed_tools=[]`, $0.05 budget) — correct least-privilege boundary; prompt injection in triage cannot lead to code execution or data exfiltration
- ✅ **Strict git ref allowlist** (`is_valid_git_ref`) validates `base_branch` from untrusted sources before it reaches subprocess calls
- ✅ **No `shell=True`** in any subprocess invocation — base_branch is passed as list argument, preventing command injection
- ✅ **Multi-layer budget enforcement** — daily, aggregate, and per-run caps operate independently; `daily_budget_usd` has no default (must be explicitly configured)
- ✅ **Circuit breaker persists across restarts** — prevents runaway failure loops after crash recovery
- ✅ **Input sanitization** on triage prompt via `sanitize_slack_content()`
- ✅ **No secrets committed**, no new dependencies

**Non-blocking suggestions:**
1. Triage prompt doesn't use `<slack_message>` delimiters like `format_slack_as_prompt` — low risk given zero-tool-access, but worth aligning for consistency
2. Base branch checkout runs before preflight dirty-state check — minor UX concern
3. Config reload per queue item means config corruption increments failure counter — minor

All 365 tests pass. Review artifact written to `cOS_reviews/reviews/staff-security-engineer/round_2.md`.