Compare Claude Code and Codex on the same real code-change task with isolated worktrees, identical gates, transcripts, time, and cost.
Use when repository docs, README, AGENTS.md, rules, plans, chronicles, or ATLAS are stale or current work changed their lifecycle; archives task history, with --clean for corpus-wide cleanup.
Research current best practices and turn the evidence into a clear recommendation. Use for state-of-the-art, evidence-based, optimal-approach, comparison, or pros-and-cons questions in any field.
Use when the user wants to do brainstorming, choose an approach, design something or clarify an ambiguous or consequential change before planning or implementation.
Add CHANGELOG.md entries, derive them from commits, or cut a Keep a Changelog and SemVer release.
Define or implement regression proof: test strategy, black-box/integration tests, KPIs, thresholds, audits, or missing tests.
Use when the user asks to check a plugin or skill with behavioral evals, compare it with HEAD, or investigate a behavioral regression.
Explain a diff, branch, PR, patch, or review packet; use after Full-path verification when the change teaches a useful business or technical concept.