# Review by Staff Security Engineer (Round 3)

Here is my review as **Staff Security Engineer**:

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## Staff Security Engineer Review — Round 3

### Methodology

I reviewed the full diff (`git diff main...HEAD` across 12 files), read every line of the implementation in `agent.py`, `config.py`, `models.py`, and `orchestrator.py`, checked all 234 relevant tests pass, searched for credential/secret leakage, and assessed the architecture against the PRD's 10 functional requirements.

### Completeness Assessment

All 10 functional requirements are implemented:

| FR | Status | Notes |
|----|--------|-------|
| FR-1 | ✅ | `_friendly_error()` detects overloaded/529/503 via `_TRANSIENT_PATTERNS` regex |
| FR-2 | ✅ | `_is_transient_error()` checks structured `status_code` first, regex fallback second |
| FR-3 | ✅ | Retry loop in `run_phase()` with full jitter backoff, restart-from-scratch semantics |
| FR-4 | ✅ | Defaults: `max_attempts=3`, `base_delay=10.0`, `max_delay=120.0` |
| FR-5 | ✅ | `RetryConfig` dataclass nested under `ColonyConfig.retry` |
| FR-6 | ✅ | `fallback_model` opt-in, disabled by default, validated against `VALID_MODELS` allowlist |
| FR-7 | ✅ | `_SAFETY_CRITICAL_PHASES` hard-blocks fallback on review/decision/fix using `Phase.XXX.value` |
| FR-8 | ✅ | Retry messages via `ui.on_text_delta()` or `_log()` |
| FR-9 | ✅ | `RetryInfo` dataclass on `PhaseResult`, serialized to/from run log JSON |
| FR-10 | ✅ | Parallel phases retry independently within their own `run_phase()` |

### Security Findings

**1. Safety-critical phase guard — SOLID** ✅
The `_SAFETY_CRITICAL_PHASES` set now uses `Phase.REVIEW.value`, `Phase.DECISION.value`, `Phase.FIX.value` instead of raw strings. Renaming an enum member triggers `AttributeError` at import time — exactly the right failure mode. This was a previous round finding, now fixed.

**2. Fallback model allowlist — SOLID** ✅
`_parse_retry_config()` validates `fallback_model` against `VALID_MODELS` frozenset. A config file cannot inject an arbitrary model string. Good.

**3. Config validation — SOLID** ✅
`max_attempts >= 1`, `base_delay_seconds >= 0`, `max_delay_seconds >= 0` all validated. `max_attempts > 10` emits a warning. This prevents a misconfigured YAML from creating an infinite retry loop.

**4. Error message sanitization — SOLID** ✅
`_friendly_error()` returns generic messages ("API is temporarily overloaded (529). Will retry..."), not raw API response bodies. No risk of leaking internal API details to logs or UI.

**5. Resume session cleared on retry — SOLID** ✅
`current_resume = None` after first transient error (line ~280). Dead sessions are not propagated to retries. This was a previous round HIGH finding, now fixed.

**6. Budget amplification — ACCEPTABLE RISK** ⚠️
With `fallback_model` configured, total attempts can reach `2 * max_attempts` (default: 6). Each attempt burns the full phase budget. The per-run budget cap in the orchestrator provides the outer safety net, and the `max_attempts > 10` warning helps prevent egregious misconfiguration. Acceptable.

**7. `RetryInfo(**p["retry_info"])` trusts run log JSON** — LOW ⚠️
At `orchestrator.py:2441`, `RetryInfo(**p["retry_info"])` splats the entire JSON dict into the constructor without explicit field extraction. If a corrupted or future-version run log contains extra keys, this raises `TypeError` (crash, not silent corruption). Since `RetryInfo` is a frozen dataclass, it won't accept unexpected fields — **this is safe by construction**, but fragile against forward-compatibility. A minor robustness concern, not a security vulnerability, since run logs are local files written by the system.

**8. No secrets in committed code** ✅
Searched all changed files for credential patterns. Clean.

**9. `retry_config=config.retry` threaded through all orchestrator call sites** — ACKNOWLEDGED
This is tech debt (20+ call sites), not a security issue. All call sites correctly pass `config.retry`. Missing a call site means that phase falls back to `RetryConfig()` defaults — a safe degradation.

### Test Coverage

- **234 tests pass** across `test_agent.py`, `test_config.py`, `test_models.py`
- Key security-relevant tests present:
  - `test_fallback_blocked_on_safety_critical_phases` — verifies review/decision/fix cannot fall back
  - `test_resume_cleared_after_transient_error` — verifies dead sessions aren't reused
  - `test_529_substring_in_filepath_not_overloaded` / `test_529_as_port_not_overloaded` — verifies regex doesn't false-positive
  - `test_invalid_fallback_model_raises` — verifies allowlist enforcement
  - `test_max_attempts_zero_raises` — verifies config validation

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VERDICT: approve

FINDINGS:
- [src/colonyos/orchestrator.py:2441]: `RetryInfo(**p["retry_info"])` trusts run log JSON without explicit field extraction — safe by frozen dataclass construction but fragile against forward-compatibility (extra fields cause TypeError crash). LOW.
- [src/colonyos/orchestrator.py]: `retry_config=config.retry` threaded through 20+ call sites — tech debt acknowledged across reviews; missing a call site degrades safely to defaults. Not a blocker.
- [src/colonyos/agent.py:94-95]: `_friendly_error()` now uses `_TRANSIENT_PATTERNS` regex — consistent with `_is_transient_error()`. Previous inconsistency finding resolved.
- [src/colonyos/config.py:22-25]: `_SAFETY_CRITICAL_PHASES` now uses `Phase.XXX.value` — previous fragility finding resolved.
- [src/colonyos/agent.py:~280]: `current_resume = None` after transient error — previous HIGH finding (resume leak) resolved.

SYNTHESIS:
From a security standpoint, this implementation is approved. The three critical security properties are all correctly implemented: (1) safety-critical phases hard-block model fallback, enforced via enum-derived phase set that fails loudly on rename; (2) fallback model is validated against an allowlist at config parse time; (3) error messages are sanitized to prevent API response body leakage. The resume session leak (previous round HIGH) is fixed — dead sessions are not propagated to retries. Budget amplification is bounded by the per-run cap and config validation. The only remaining concern is the `RetryInfo(**p["retry_info"])` JSON deserialization pattern, which is safe today (frozen dataclass rejects extra fields with TypeError) but would benefit from explicit field extraction for forward-compatibility. All 234 tests pass, including targeted security-relevant tests for fallback blocking, resume clearing, and false-positive regex protection. No secrets, no credential leakage, no destructive operations without safeguards. Approved.