# Staff Security Engineer Review — Round 2
## Handle 529 Overloaded Errors with Retry and Optional Model Fallback

**Branch:** `colonyos/the_following_github_issue_is_the_source_feature_description_treat_it_as_the_pri`
**PRD:** `cOS_prds/20260329_225200_prd_the_following_github_issue_is_the_source_feature_description_treat_it_as_the_pri.md`
**Test Results:** 440/440 passed

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### Checklist Assessment

**Completeness**
- [x] All 10 functional requirements (FR-1 through FR-10) are implemented
- [x] All tasks in the task file are marked complete
- [x] No placeholder or TODO code remains (one SDK design-note comment is appropriate)

**Quality**
- [x] All 440 tests pass (zero regressions, 6+ new test classes with comprehensive coverage)
- [x] Code follows existing project conventions (`RetryConfig` mirrors `CIFixConfig`/`RecoveryConfig` pattern)
- [x] No unnecessary dependencies added (`random`, `re` are stdlib)
- [x] No unrelated changes (previous `.colonyos/daemon_state.json` issue fixed in this iteration)

**Safety**
- [x] No secrets or credentials in committed code
- [x] No destructive operations without safeguards
- [x] Error handling present for all failure cases
- [x] Input validation on config values (`max_attempts >= 1`, delays non-negative, model allowlist)

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### Security-Specific Findings

**1. [src/colonyos/agent.py:248] — `resume` session ID leaks into retry attempts.**
When `run_phase()` is called with `resume="sess-abc123"`, every retry attempt passes the same `resume` session ID to `ClaudeAgentOptions`. After a 529, there is no valid session to resume — the query threw before yielding a `ResultMessage`. Passing a stale `resume` value on retry could either silently fail (SDK ignores invalid session) or cause unexpected behavior (resuming a partial/corrupted conversation state). The `resume` kwarg should be cleared to `None` after the first attempt fails. **Severity: LOW** — the PRD explicitly notes restart-from-scratch semantics (Non-Goals: "Resume-based retry"), so this is a correctness gap, not a data-leak vector. In practice, 529 callers are unlikely to pass `resume`, but defensive code should enforce the invariant.

**2. [src/colonyos/agent.py:97] — `_friendly_error()` uses plain substring matching for "529" while `_is_transient_error()` uses word-boundary regex.**
The detection logic is inconsistent: `_is_transient_error()` correctly uses `\b529\b` to avoid false positives, but `_friendly_error()` still does `"529" in lower` which would match "error_5290" or "port:5291". Low practical risk since `_friendly_error()` only controls the display message, not retry behavior, but it's an inconsistency that should be aligned. **Severity: LOW.**

**3. [src/colonyos/config.py:22] — `_SAFETY_CRITICAL_PHASES` uses raw strings instead of `Phase.XXX.value`.**
Previously flagged across multiple reviews and still unaddressed. If the `Phase` enum values are ever renamed, the safety gate silently breaks — fallback would be allowed on review/decision/fix phases. This is a latent security defect. Should be `frozenset({Phase.REVIEW.value, Phase.DECISION.value, Phase.FIX.value})`. **Severity: MEDIUM** (defense-in-depth concern).

**4. [src/colonyos/agent.py:266] — `_is_transient_error(exc)` called redundantly.**
At line 264, `_is_transient_error(exc)` is evaluated for the outer condition. At line 266, it's called again (ternary). At line 268, it's called a third time. This is 3 calls on the same exception object. While not a security issue per se, redundant exception inspection increases the attack surface if error string representation has side effects (some libraries implement `__str__` with I/O). Extract to a local boolean. **Severity: LOW.**

**5. [src/colonyos/orchestrator.py:2441] — `RetryInfo(**p["retry_info"])` deserialization trusts run log JSON.**
The `_load_run_log` function deserializes `retry_info` from JSON using `RetryInfo(**p["retry_info"])`. If a malicious actor can tamper with the run log JSON on disk (e.g., symlink attack, shared filesystem), they could inject unexpected kwargs. `RetryInfo` is a frozen dataclass so arbitrary attribute injection is limited, but defensive parsing (explicit field extraction like other config parsers do) would be more robust. **Severity: LOW** — run logs are local to the repo and the frozen dataclass provides reasonable protection.

**6. [src/colonyos/config.py] — Fallback model validation against `VALID_MODELS` is correct.**
The allowlist check `if fallback_model not in VALID_MODELS` properly prevents arbitrary model strings from being injected via config. Good.

**7. [src/colonyos/agent.py] — `permission_mode="bypassPermissions"` propagated to retry and fallback attempts.**
This is pre-existing behavior, not introduced by this PR. But it's worth noting: when a fallback model (potentially weaker, more susceptible to prompt injection) runs with `bypassPermissions`, it has full tool access. The safety-critical phase block (FR-7) mitigates the highest-risk phases, but `implement` and `plan` phases still run the fallback model with full permissions. The PRD's Open Question #3 acknowledges this. No action required for this PR, but worth tracking.

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### Previous Round Findings — Status

| Finding | Status |
|---------|--------|
| `.colonyos/daemon_state.json` committed | **FIXED** — added to `.gitignore` |
| `_TRANSIENT_PATTERNS` allocated per call | **FIXED** — hoisted to module-level |
| String matching "503"/"529" false positives | **FIXED** — word-boundary regexes |
| `retry_info: dict` breaks typed convention | **FIXED** — frozen `RetryInfo` dataclass |
| `run_phase()` 200+ line nesting | **FIXED** — `_run_phase_attempt()` extracted |
| No upper bound on `max_attempts` | **FIXED** — warning log at >10 |
| `_SAFETY_CRITICAL_PHASES` raw strings | **NOT FIXED** — still raw strings |
| `resume` kwarg leaks into retry | **NOT FIXED** — see Finding #1 |

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