# Review by Principal Systems Engineer (Google/Stripe caliber) (Round 2)

## Review Complete

Here's my assessment as Principal Systems Engineer:

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VERDICT: approve

FINDINGS:
- [src/colonyos/agent.py]: Clean 4-line change threading `resume` parameter via conditional kwargs spread into `ClaudeAgentOptions`. Minimal surface area change.
- [src/colonyos/cli.py:_run_direct_agent]: Graceful fallback retry (once without resume on failure) is well-designed. Minor nit: the original resume failure is swallowed silently — a `logger.debug()` on the fallback path would aid operational debugging without affecting UX.
- [src/colonyos/cli.py:_run_callback]: TUI closure correctly maintains `last_direct_session_id` with proper clearing on mode switch, failure, and `/new` command. No race conditions — the callback runs in a single worker thread.
- [src/colonyos/cli.py:_run_repl]: CLI REPL mirrors TUI session logic symmetrically. Both paths clear state identically on mode transitions.
- [src/colonyos/cli.py:session ID validation]: Defense-in-depth regex guard (`[A-Za-z0-9_-]+`) prevents injection of malformed session IDs into the SDK. Silent fallback to `None` is the right UX choice.
- [tests/]: 34 tests covering all layers — agent resume threading, direct-agent tuple return, session ID validation, REPL state management, and full end-to-end lifecycle (resume → follow-up → mode-switch → /new reset). Comprehensive.

SYNTHESIS:
This is a clean, minimal implementation that correctly leverages the SDK's native session resume mechanism rather than building custom transcript replay. The architecture is sound: state lives in closures (not global singletons), the fallback path handles stale sessions gracefully with exactly one retry, and the `/new` escape hatch provides explicit user control. The blast radius is small — if resume fails, users get a fresh session transparently. Test coverage is thorough across all layers. The only operational concern is silent swallowing of resume failures (a debug log would help diagnose systematic SDK issues at 3am), but this is a minor nit that doesn't block approval. Production-ready.
