# Review by Staff Security Engineer (Round 5)

I have all the information I need. Here is my review:

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## Staff Security Engineer Review — Round 5 (Final)

I've performed a holistic assessment of the full implementation diff across `config.py`, `orchestrator.py`, and all test files against the PRD requirements.

### Checklist Assessment

**Completeness:**
- ✅ FR-1/FR-2: Default flipped to `False` in both `ParallelImplementConfig` dataclass and `DEFAULTS` dict
- ✅ FR-3: Sequential task runner `_run_sequential_implement()` implemented (~250 lines)
- ✅ FR-4: Uses `TaskDAG.topological_sort()` from `dag.py`
- ✅ FR-5: Per-task `git commit` between each task execution
- ✅ FR-6: Failed tasks → dependents marked BLOCKED, independent tasks continue
- ✅ FR-7: Budget divided evenly (`per_phase / task_count`)
- ✅ FR-8: Warning logged when `parallel_implement.enabled` explicitly set to `True`
- ✅ FR-9: Returns `PhaseResult` with per-task cost/duration/status artifacts
- ✅ FR-10: Parallel orchestrator code untouched; existing tests updated for new default

**Quality:**
- ✅ 32/32 tests pass in `test_sequential_implement.py`
- ✅ Existing parallel tests updated correctly (explicit `enabled=True` where needed)
- ✅ Code follows established patterns (same `_build_*_prompt` / `_run_*_implement` naming)
- ✅ No unnecessary dependencies added (`time` is stdlib)
- ✅ No unrelated changes

**Safety (my primary focus):**
- ✅ **Selective staging**: Uses `git diff --name-only` + `git ls-files --others` then `git add -- <files>` — no `git add -A`
- ✅ **Secret filtering**: `_is_secret_like_path()` applied to all changed files before staging, with audit log of skipped files
- ✅ **Subprocess timeouts**: All `subprocess.run()` calls have `timeout=30`
- ✅ **Commit message sanitization**: `sanitize_untrusted_content()` applied to task descriptions before embedding in commit messages
- ✅ **Per-task audit trail**: Each task logs what files it modified — clean forensic trail
- ✅ **Memory/context injection**: `_inject_memory_block()` and `_drain_injected_context()` properly wired per-task
- ✅ **No secrets in committed code**: Verified no credentials, tokens, or env values in the diff

VERDICT: approve

FINDINGS:
- [src/colonyos/orchestrator.py:1329-1340]: Secret filter covers `.env*`, `.pem`, `.p12`, `.pfx`, `.key`, `id_rsa/dsa/ecdsa/ed25519`, `.ssh/` directory — but does not cover `.npmrc`, `.pypirc`, `*.keystore`, `*.jks`, `*.gpg`, `token.json`, `service_account.json`. This is a pre-existing gap, not introduced by this PR. Recommend extending in a follow-up. (LOW)
- [src/colonyos/orchestrator.py:830-835]: Agent receives full task descriptions in prompts. If a malicious actor could inject content into the task file (e.g., via a compromised plan phase), they could attempt prompt injection. Mitigated by: (a) task files are generated by ColonyOS planner, not arbitrary user input, and (b) `sanitize_untrusted_content()` is applied at commit-message boundary. (LOW)
- [src/colonyos/orchestrator.py:860-905]: Subprocess calls for git operations use `capture_output=True` and `timeout=30` — correct. However, if `safe_files` list is extremely large (thousands of files), the `git add --` command line could exceed `ARG_MAX`. Practically unlikely in a per-task context. (INFO)

SYNTHESIS:
This implementation is **approved** from a security perspective. The sequential-by-default architecture is a net security improvement over the parallel default: it eliminates inter-worktree data leakage, removes the merge conflict resolution agent (which had elevated permissions to modify arbitrary files), and produces a clean per-task audit trail via individual commits with sanitized messages. All critical security controls are in place: selective file staging with secret filtering, subprocess timeouts on every shell-out, commit message sanitization via `sanitize_untrusted_content()`, and per-task audit logging of modified files. The 32 new tests include security-specific assertions that verify subprocess call arguments (not just return values). The two LOW findings (expand secret filter, theoretical prompt injection via task descriptions) and one INFO finding (ARG_MAX edge case) are appropriate follow-ups and do not block shipping. All prior-round security findings have been verified as fixed with test coverage.
