agents-md-setup

Make `AGENTS.md` the single source of truth for agent/project instructions, and point every tool's file at it via symlink. One file, read by all agents — no duplication, no drift.

Why this layout

• AGENTS.md is the emerging cross-tool standard (Cursor, Codex, and others read

it).

• Claude Code reads CLAUDE.md. You cannot make the harness read AGENTS.md

instead via a prompt or a skill — but a symlink CLAUDE.md → AGENTS.md means Claude opens CLAUDE.md and gets AGENTS.md's content. That is the mechanism; nothing else is needed.

• Result: edit AGENTS.md only; every agent stays in sync.

Decision: what's already there?

1. Neither file → create AGENTS.md from the template below.
2. Only `CLAUDE.md` (a real file) → make it the source of truth:

   git mv CLAUDE.md AGENTS.md       # preserve history (or: mv if not tracked)

1. Only `AGENTS.md` → keep it as-is (good).
2. Both exist as real files → do NOT blindly overwrite. Compare them; merge

into AGENTS.md (it wins as the canonical file), confirm with the user if the contents differ, then remove the standalone CLAUDE.md.

1. `CLAUDE.md` already a symlink → `AGENTS.md` → already done; stop.

Create the symlink

ln -s AGENTS.md CLAUDE.md
git add AGENTS.md CLAUDE.md        # git stores it as a real symlink (mode 120000)

Verify it committed as a symlink, not a copy:

git ls-files -s CLAUDE.md          # mode should be 120000

Optionally point other tools at the same file:

ln -s AGENTS.md GEMINI.md
mkdir -p .github && ln -s ../AGENTS.md .github/copilot-instructions.md

Monorepos (Turborepo / workspaces)

Keep a root `AGENTS.md` for repo-wide conventions (with the CLAUDE.md symlink as above), then add a scoped `AGENTS.md` in each workspace that needs its own rules — apps/<app>/AGENTS.md, packages/<pkg>/AGENTS.md — each with its own sibling symlink created from inside that directory so the target is relative:

cd apps/web && ln -s AGENTS.md CLAUDE.md   # CLAUDE.md -> ./AGENTS.md (same dir)

• Claude Code reads the nearest CLAUDE.md for the files it's working on, so

nested files supplement the root rather than replace it. Put repo-wide things at the root; put only the package-specific delta in each workspace — don't duplicate the root.

• Always make each symlink relative to its own folder (`ln -s AGENTS.md

CLAUDE.md while cd`'d into the workspace), never pointing back at the root — relative same-dir links survive checkout/move.

• Turborepo itself doesn't read these files (they're for agents), so **no

turbo.json change is needed**. If you want them surfaced, you can still note the convention in the root AGENTS.md.

README

If there's no README.md, scaffold a minimal one (project name, one-line description, setup/run commands). Keep human-facing docs in README.md and agent instructions in AGENTS.md — don't merge the two.

Windows / CI caveat (important)

Git symlinks need core.symlinks=true and can break on Windows checkouts or some CI runners (the symlink lands as a text file containing AGENTS.md). If the project targets Windows, prefer the fallback: a tiny real CLAUDE.md whose entire content is a pointer —

See [AGENTS.md](./AGENTS.md) for project + agent instructions.

— accepting that it must be kept in sync manually (or via a check). Symlink is better everywhere symlinks are reliable.

Don't undo it later

If you see CLAUDE.md as a symlink to AGENTS.md, that's intentional — edit AGENTS.md, never replace the symlink with a copy.

AGENTS.md template

# AGENTS.md

Instructions for AI agents and humans working in this repository.
`CLAUDE.md` is a symlink to this file; this file is the source of truth.

## Project overview
<what this is, in 1–3 sentences>

## Commands
- install: `…`
- dev: `…`
- build: `…`
- test / lint / format: `…`

## Conventions
- <code style, language/runtime, formatting>
- Commit messages: <e.g. Conventional Commits>
- <anything an agent must not do, or must always do>

## Layout
<key directories and what lives where>