Brain Setup

brain-setup

This skill bootstraps a project into the Open Project Brain Standard: it drops in the protocol entry point and the brain/ skeleton so the brain-page and brain-ingest skills (and the brain CLI) have something to work with. It is idempotent — safe to run again on an already-initialized project.

Preferred one-shot path: from the project root run:

node <brain-page-bundle>/bin/brain.mjs init

That command ensures BRAIN.md, scaffolds empty brain data (brainRoot-aware), and default-wires CLAUDE.md + AGENTS.md (create if missing; if present, only update/append the marked brain block — never whole-file overwrite). Use the steps below when you need the optional pre-commit hook, the optional Claude Code or Codex SessionStart hook, or are explaining the flow.

NEVER hand-edit any file under the brain directory. All reads and writes MUST go through the brain CLI. Manual edits are unsupported and illegitimate. This scaffold creates the brain once; from then on every read and write is a brain subcommand. There is no validator and nothing at the file layer can catch a bad manual edit, so a hand edit silently breaks the brain's invariants.

Run this from the target project's root. The skill bundle ships the templates under assets/ and the hook under hooks/; resolve <this-skill-bundle> to the directory this SKILL.md lives in.

Core invariant: there is exactly one brain, at the resolved location. The brain's data directory is location-independent — it lives at ./brain by default, but a MindMux-managed project redirects it via brainRoot in ./.mindmux/preferences.json (often an absolute path to an external sidecar directory). This skill MUST resolve that location before scaffolding, and MUST NOT create a second, local ./brain when a brainRoot is set — doing so produces a split brain (an empty local skeleton shadowing the real external brain). The BRAIN.md protocol document is separate: it always lives in the project root regardless of where the brain data lives.

Steps

1. Ensure BRAIN.md (the protocol document) is in the project root

BRAIN.md is the read/write contract that the agent reads to learn how to use the brain. It always belongs in the project root, independent of where the brain data lives.

• Present → leave it untouched (never overwrite project content).
• Absent → copy assets/BRAIN.md → ./BRAIN.md.

Do not stop here just because BRAIN.md exists — its presence says nothing about whether the brain data is set up. Always continue to step 2 to resolve and check the data location.

2. Resolve the brain data location, then scaffold there only if empty

First, resolve where the brain data actually lives — never assume ./brain. Ask the CLI:

node <brain-page-bundle>/bin/brain.mjs brain-dir

(The brain-page skill carries the CLI; in the brain.md source repo it is skills/brain-page/bin/brain.mjs, globally it is e.g. ~/.claude/skills/brain-page/bin/brain.mjs.)

brain brain-dir reads brainRoot from ./.mindmux/preferences.json when present (otherwise falls back to ./brain) and prints, on separate lines: the resolved directory, a human-readable origin, source: (brainRoot or default), exists: (true/false), and populated: (true/false — whether the location already holds a root page or any page under pages/). Read those lines instead of guessing or stat-ing by hand.

Branch on the resolved state:

• populated: true → the brain already exists. Do NOT scaffold. Tell the user the brain lives at <resolved dir>. If source: brainRoot, make it explicit: "this project's brain is redirected to an external directory (<resolved dir>) and is managed there — leaving it untouched." Then continue to step 3 (wire) and the optional hooks (steps 4–5). Never lay down a local ./brain in this case.

• populated: false → scaffold the skeleton into the resolved directory (the brainRoot target when redirected, otherwise ./brain). Copy assets/brain/ → <resolved dir>/ — this brings the six root page templates (background / architecture / flow / mindmap / stack / roadmap), a generated index.md, and an empty pages/ directory. Copy each destination file only if it does not already exist (never overwrite). Never create a second local ./brain when source: brainRoot — always scaffold at the resolved path. After copying, run reindex so the index reflects the present pages:

  node <brain-page-bundle>/bin/brain.mjs reindex

  (reindex resolves the same location, so it writes the index in the right place automatically.)

No example pages are scaffolded; the page format is documented in BRAIN.md and the brain-page skill.

3. Wire the agent-config files via brain wire (default both files)

The project's agent-config files must point at BRAIN.md so agents pick up the contract. Wiring is deterministic — done by the CLI, not by hand. Do not hand-write @import lines or template paragraphs. Do not ask which agents to wire — default to both config files unless the user explicitly requests a subset.

Run (default — no --agent required):

node <brain-page-bundle>/bin/brain.mjs wire

Equivalent: wire --agent all. Optional subset: --agent claude-code or comma-separated list. Supported ids: claude-code, codex, opencode, cursor, pi, all.

What the command does (so you can explain it):

• Default maps to both ./CLAUDE.md (claude-code block with @import) and ./AGENTS.md (shared block for codex / opencode / cursor / pi).
• Writes one unified, neutral, self-contained brain block — wrapped in <!-- BEGIN brain.md --> … <!-- END brain.md --> — that tells the agent to read ./BRAIN.md, states the session-companion rules (load brain at task start; capture decisions/constraints when they settle during coding; skip pure implementation; reverse/update when overturning; all via the brain CLI; never hand-edit), and notes the four brain skills are installed globally.
• Claude additionally gets @import ./BRAIN.md; Codex additionally gets native notes/history guidance with current-page reads after context rollover.
• Idempotent via the markers: absent file → created; existing file without markers → block appended (preserve user content); existing marked block → replaced in place (upgrades, never duplicates). Never whole-file overwrite outside the markers.