# Review by Staff Security Engineer (Round 2)

I now have a thorough understanding of the implementation. Here is my review:

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## Staff Security Engineer Review

### Completeness

- **FR-1 (Intent Classification)**: ✅ Four categories implemented (`CODE_CHANGE`, `QUESTION`, `STATUS`, `OUT_OF_SCOPE`) in `RouterCategory` enum.
- **FR-2 (Reuse Slack Triage)**: ✅ `triage_message()` in `slack.py` delegates to the unified `route_query()`, with `_triage_message_legacy()` fallback for `triage_scope`.
- **FR-3 (Two-Stage Q&A)**: ✅ Stage 1: haiku classification, no tools, $0.05. Stage 2: `answer_question()` with read-only tools, configurable model/budget.
- **FR-4 (Entry Points)**: ✅ Integrated in `colonyos run`, REPL, and Slack watcher. Correctly excluded from `auto`, `queue`, and explicit verb commands.
- **FR-5 (Fail-open)**: ✅ Low confidence falls back to pipeline. JSON parse failure falls back to `CODE_CHANGE`. Unknown categories fall back to `CODE_CHANGE`.
- **FR-6 (--no-triage)**: ✅ CLI flag implemented.
- **FR-7 (Config)**: ✅ `RouterConfig` dataclass with all fields, parsed from YAML.
- **FR-8 (Audit Logging)**: ✅ `log_router_decision()` writes to `.colonyos/runs/triage_<timestamp>.json`.

### Security Assessment

**Strengths:**
1. **Least privilege enforcement is solid.** Router phase: `allowed_tools=[]` (zero tools). Q&A phase: `allowed_tools=["Read", "Glob", "Grep"]` — genuinely read-only. This is the right two-tier privilege model.
2. **Input sanitization is consistent.** Both `_build_router_prompt()` and `_build_qa_prompt()` call `sanitize_untrusted_content()` on user input before injecting into prompts. The audit logger also sanitizes before persisting.
3. **Fail-open design is correct from a security standpoint.** Routing to the full pipeline (which has its own review gates) is safer than silently dropping requests.
4. **Budget caps are tight.** $0.05 for classification, $0.50 for Q&A — limits blast radius of prompt injection attempts that try to burn credits.
5. **Test coverage is excellent.** 236 tests pass. Dedicated tests for prompt injection sanitization, fail-open fallback, malformed JSON handling, and audit log sanitization.

**Concerns (non-blocking):**

1. **`permission_mode="bypassPermissions"` is inherited by default** for both the router and Q&A phases (line 214 of `agent.py`). While `allowed_tools=[]` and `allowed_tools=["Read", "Glob", "Grep"]` constrain available tools, the `bypassPermissions` mode means if the tool allowlist enforcement has any bypass bugs in the SDK, the agent would have unrestricted access. This is an existing architectural pattern (all phases use it), not a regression, so not blocking.

2. **Audit log stores sanitized prompt, not raw prompt.** `log_router_decision()` sanitizes before logging (line 411 of `router.py`). For forensic purposes, it's sometimes useful to have the raw input to understand attack attempts. However, logging raw untrusted input introduces its own risks (log injection), so this is a reasonable tradeoff.

3. **Q&A instruction template (`qa.md`) is a static file on disk.** If an attacker can write to the repo, they could modify this template to change the Q&A agent's behavior. This is mitigated by the fact that the Q&A agent only has read-only tools, so even with a modified system prompt, the blast radius is limited to information disclosure (not code execution). Acceptable risk.

4. **No rate limiting on router calls.** A user in the REPL could spam questions rapidly, each triggering a classification + Q&A call. This is a minor cost concern, not a security vulnerability. Existing budget caps mitigate the financial impact.

### Quality

- All 236 tests pass.
- Code follows existing project conventions (dataclasses, `run_phase_sync` pattern, lazy imports).
- No unnecessary dependencies added.
- No unrelated changes (the `config.model` default change from `"sonnet"` to `"opus"` in the test matches the project's stated preference for opus).
- No secrets or credentials in committed code.
- Error handling is comprehensive (JSON parse failures, LLM call failures, file I/O failures in audit logging).

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VERDICT: approve

FINDINGS:
- [src/colonyos/router.py:234-241]: Router uses `run_phase_sync` which defaults to `permission_mode="bypassPermissions"` — mitigated by `allowed_tools=[]` but defense-in-depth would benefit from explicit `permission_mode="default"` for zero-tool phases.
- [src/colonyos/router.py:411]: Audit log sanitizes prompt before persisting — good for safety, but raw input would aid forensic analysis of prompt injection attempts. Acceptable tradeoff.
- [src/colonyos/router.py:352-353]: Q&A agent correctly restricted to `["Read", "Glob", "Grep"]` — proper least-privilege for read-only codebase exploration.
- [src/colonyos/instructions/qa.md]: Static template file — if repo is compromised, attacker could alter Q&A behavior, but blast radius is limited to information disclosure due to tool restrictions.

SYNTHESIS:
From a security perspective, this implementation follows the principle of least privilege well. The two-tier design (zero-tool classification → read-only Q&A) is sound. Input sanitization is applied consistently at all trust boundaries (prompt construction and audit logging). The fail-open behavior correctly defaults to the full pipeline which has its own review gates. The main area for future hardening is explicitly setting `permission_mode` to a more restrictive value for phases that don't need bypass permissions (router and Q&A), but this is an existing architectural pattern across the codebase and not a regression. All tests pass, no secrets are committed, and error handling is thorough. This is ready to ship.