Bootstrap agent config for a repository

Produce a CLAUDE.md and a symlinked/parallel AGENTS.md that are grounded in
the real repo, not generic boilerplate. A good config is the single highest-ROI
thing for agent productivity in a codebase — it pays for itself on the first task.

Steps

1. Detect the stack. Run the helper to get a fast inventory:

   bash "${CLAUDE_SKILL_DIR}/detect-stack.sh" .

   It reports languages, package managers, build/test/lint commands, monorepo
   layout, and whether ADRs/CI exist.

2. Verify, don't trust. Confirm the detected build/test commands actually exist
   (read the Makefile / package.json / justfile). Read 2–3 representative source
   files to learn the real conventions (error handling, test style, naming).

3. Find the invariants. The most valuable part of a CLAUDE.md is the
   load-bearing rules — the things that cause incidents if violated. Look for
   them in: existing ADRs, ARCHITECTURE.md, SECURITY.md, README "gotchas", and
   patterns the code enforces (e.g. tenant scoping, a trust boundary, a generated
   file you must not hand-edit). Ask the user if the architecture isn't legible.

4. Draft CLAUDE.md using the structure in
   ${CLAUDE_SKILL_DIR}/../../../templates/CLAUDE.md.tmpl as a skeleton. Fill every
   placeholder with real, verified content. Sections that matter most:

   • One-sentence "what this is"
   • Languages and exact build/test/lint commands (copy-pasteable)
   • Repo layout (only the parts an agent needs)
   • Load-bearing invariants — the "what NOT to do" list
   • How to run/verify locally
     Cut anything you can't ground in the actual repo. Short and true beats long and
     aspirational.

5. Make AGENTS.md track it. Most non-Claude tools (Codex, etc.) read
   AGENTS.md. Either symlink it (ln -s CLAUDE.md AGENTS.md) so there's one
   source of truth, or write a thin AGENTS.md that says "see CLAUDE.md". Prefer
   the symlink unless the repo already has a divergent AGENTS.md.

6. Report the files written and the top 3 invariants you encoded, so the user
   can correct anything you inferred.

Quality bar

• Every command in the file runs. Every path exists. Every invariant is real.
• No "best practices" filler that isn't specific to this repo.
• If you had to guess at an invariant, mark it (verify) so the user checks it.