## Review Complete — Principal Systems Engineer (Google/Stripe caliber), Round 4

### Perspective
Distributed systems, API design, reliability, observability. What happens when this fails at 3am? Where are the race conditions? Is the API surface minimal and composable? Can I debug a broken run from the logs alone? What's the blast radius of a bad agent session?

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### Summary of Changes Since Round 3

Both cosmetic findings from Round 3 have been resolved in commit `dbe17bd`:
1. `type(repo_map_config)(...)` → `dataclass_replace(repo_map_config, max_tokens=max_tokens)` in `cli.py`
2. Duplicated comment removed from `repo_map.py`

No functional changes. All Round 3 findings were cosmetic-only.

### Verification

| Suite | Count | Status |
|-------|-------|--------|
| test_repo_map.py | 95 | ✅ All pass |
| test_config.py (RepoMapConfig) | 8 | ✅ All pass |
| test_cli.py (TestMapCommand) | 5 | ✅ All pass |
| test_orchestrator.py | 228 | ✅ All pass |
| **Total** | **336** | **Zero failures** |

### Remaining Non-blocking Observations

1. **[src/colonyos/repo_map.py:SENSITIVE_PATTERNS]**: Missing `*.p12`, `*.pfx`, `id_rsa*`, `*.jks`, `*.keystore` patterns. Not a blocker: (a) these are rarely git-tracked, (b) the map exposes only file names not contents, (c) users can add these via `exclude_patterns` config.

2. **[src/colonyos/repo_map.py:680-684]**: Greedy truncation breaks on first oversized file, leaving ~5-10% budget slack. Correct tradeoff — ranked order means dropped files are the least relevant, and a knapsack solver would add complexity for marginal gain.

3. **[src/colonyos/repo_map.py:724-729]**: Sequential file-by-file symbol extraction. For repos at the 2000-file cap this takes 1-3 seconds. Acceptable for V1; `ThreadPoolExecutor` could parallelize the I/O if profiling ever shows need.

### Reliability Checklist (unchanged from Round 3)

- ✅ **Blast radius: zero** — `generate_repo_map()` wrapped in `try/except Exception` in `_run_pipeline()` and `run_ceo()`, fail-closed to empty string
- ✅ **No race conditions** — map generated once as a string, passed by value to a pure function 9 times, no shared mutable state
- ✅ **Resource bounds** — `_MAX_PARSE_SIZE` (1MB), `max_files` (2000), `subprocess.run(timeout=30)`: no OOM, no spin, no hang
- ✅ **Debuggable** — `colonyos map` CLI reproduces exactly what the agent sees; warning logs on every degraded path
- ✅ **No new dependencies** — stdlib only (`ast`, `re`, `pathlib`, `subprocess`, `fnmatch`)

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VERDICT: approve

FINDINGS:
- [src/colonyos/repo_map.py:SENSITIVE_PATTERNS]: Missing `*.p12`, `*.pfx`, `id_rsa*` patterns — low severity, configurable workaround exists
- [src/colonyos/repo_map.py:680-684]: Greedy truncation leaves ~5-10% budget slack — correct tradeoff for ranked-order insertion
- [src/colonyos/repo_map.py:724-729]: Sequential extraction could be parallelized for large repos — acceptable V1 latency

SYNTHESIS:
All findings from previous rounds are resolved. The implementation is operationally sound: zero blast radius on failure, no shared mutable state, bounded resource consumption at every layer, and full debuggability via CLI and logs. 336 tests pass with real git integration, zero regressions. The three remaining observations are performance and defense-in-depth notes for future iterations, not blocking issues. From a reliability engineering perspective, this module cannot crash a pipeline run, cannot OOM, cannot hang, and produces a clear warning trail when degraded. Ship it.
