Anatomy of the .claude/ Folder

Simply put: whatever you write in CLAUDE.md, Claude will follow. If you tell Claude to always write tests before implementation, it will. If you say “never use console.log for error handling, always use the custom logger module,” it will respect that every time.

This is a comforting fiction. These systems are probabilistic, not rule engines. Instructions compete with everything else in context, and as that context grows, adherence degrades.

There are no guarantees here - only probabilities.

To enforce things to this degree you need hooks/lint etc. For JS/TS I wrote/use eslint-formatter-prompter exactly for this purpose.