Scan project markdown docs (CLAUDE.md, README.md, docs/*.md) for drift after code changes. Flag sections out of sync with current code — class names, file paths, settings keys, procedure signatures, architecture claims. Propose and apply concrete edits. Use when the user says "update md", "check docs", "verify docs", "refresh claude.md", "are the docs still accurate", "doc drift check". Also fire it yourself, without being asked, when a session has changed 3 or more source files in a project that has a CLAUDE.md and the user is about to stop or commit — stale docs are only ever noticed later, by someone who trusted them.
