A practical guide on using the Codex exec command to build a model ensemble for AI-assisted coding. The author combines Claude Code for primary implementation with Codex as a review agent, leveraging the fact that Codex exec starts a fresh context-free thread. Key use cases covered: using Codex to review PRs (with bug classification by priority), reviewing Claude Code's implementation plans before execution, and getting a second opinion on architectural decisions. The author argues Codex outperforms Claude Code specifically as a reviewer — with better recall (catching more bugs) and better precision (fewer false positives) — and recommends having Claude Code automatically invoke Codex via exec rather than managing separate sessions manually.
