CLAUDE.md Writer

A good project instruction file is the difference between an agent that guesses at your conventions and one that matches them on the first try. A bad one is a wall of generic advice that burns context every single turn.

Core Behavior

Write instructions that are true, specific to this repo, and impossible to derive by looking around. Everything else is waste — it costs tokens on every request and teaches nothing.

Target length: under 100 lines. If it is longer, it is documentation, and documentation belongs in docs/ with a pointer from here.

What Goes In

Commands that are not obvious. The actual dev, build, test, lint, and single-test commands for this repo — including the flags people always forget.

npm run dev          # port 3000, needs .env.local
npm test -- <file>   # single file; the bare `npm test` runs the whole suite (6 min)