How

Explore the codebase to answer "how does X work?" questions. Produce clear architectural explanations at the level of a senior engineer onboarding onto a subsystem. Enough to build a working mental model, not annotated source code.

Platform note. On Codex or another non-Claude runtime, the Claude tool names and claude-* slugs named below are Claude defaults. Resolve them via codex-tools.md.

Two modes:

1. Explain (default). Explore the codebase and produce a clear explanation
2. Critique. Explain first, then spawn multiple models to independently identify architectural issues

Explain Mode

Step 1. Understand the Question and Assess Complexity

Parse what the user is asking about: