In the field guide I covered what an AGENTS.md is and what belongs in it. This is the hands-on follow-up: we'll build a complete AGENTS.md for a real project, one section at a time, then point an AI coding agent at it and watch the difference it makes. By the end you'll have a working file — and you'll have seen it pay off. New to AGENTS.md? It's a single Markdown file at the root of your repo that tells AI coding agents how to work in it — build steps, tests, conventions, guardrails. The ...