Project rules: AGENTS.md

🎯Goal. Give Codex standing instructions for your project with an AGENTS.md file.

1. 1Codex reads AGENTS.md before doing any work. Put working agreements in it: "Always run npm test after changing JavaScript", "Run the linter before opening a PR", and your project conventions.
2. 2Files layer by location — a global ~/.codex/AGENTS.md plus per-project files from the Git root down to your current folder; files closer to your working directory override broader ones.
3. 3AGENTS.md is an open standard used by other agents too, so the same file can guide multiple tools.

✓You'll see. Codex automatically running your test and lint steps and following your conventions without being reminded each session.

💳Cost. One-time setup — the rules ride along every session at negligible cost and save you repeating yourself.

💡Takeaway. Write the project's rules once in AGENTS.md and Codex applies them on every task, in every session.