gbrain/docs/integrations/pre-commit.md

Pre-commit hook for brain repos (v0.22.4+)

gbrain frontmatter install-hook installs a git pre-commit hook in your brain source's repo that runs gbrain frontmatter validate against staged .md and .mdx files. Malformed frontmatter blocks the commit. Bypass with git commit --no-verify.

What the hook catches

The same eight validation classes the frontmatter-guard skill and gbrain doctor's frontmatter_integrity subcheck report:

Code	What it catches
MISSING_OPEN	File doesn't start with ---
MISSING_CLOSE	No closing --- before first heading
YAML_PARSE	YAML failed to parse (syntax or structure)
SLUG_MISMATCH	slug: in frontmatter doesn't match path-derived slug
NULL_BYTES	Binary corruption (\x00) anywhere in the content
NESTED_QUOTES	title: "outer "inner" outer" shape that breaks YAML
NON_STRING_FIELD	title/type/slug is an unquoted non-string scalar (title: 123)
EMPTY_FRONTMATTER	--- ... --- with nothing meaningful between

Install

For all registered sources that are git repos:

gbrain frontmatter install-hook

For one source:

gbrain frontmatter install-hook --source <id>

For force-overwrite of an existing pre-commit hook (writes a .bak):

gbrain frontmatter install-hook --force

The hook lands at <source>/.githooks/pre-commit. If core.hooksPath is unset, the install also runs git config core.hooksPath .githooks so the hook is picked up without manual git config.

Bypass

Standard git escape hatch:

git commit --no-verify

This skips ALL pre-commit hooks. Use sparingly — the next time the user runs gbrain doctor, the issues will surface.

Uninstall

gbrain frontmatter install-hook --uninstall

If a .bak was saved during install, it's restored as the active hook. Otherwise the hook is removed cleanly.

Behavior on machines without gbrain installed

The hook script checks for gbrain on $PATH. When missing, it prints a one-line warning to stderr and exits 0 — commits aren't blocked just because a developer hasn't installed gbrain locally. Once gbrain is installed, the hook resumes blocking malformed pages.

For downstream agent forks

If your OpenClaw wraps gbrain in a host repo that's not the brain repo itself, you may want a separate hook strategy:

• Brain repo IS the host repo (gbrain skills + brain pages in one repo): install via gbrain frontmatter install-hook as above.
• Brain repo is a separate registered source (e.g. ~/brain registered as a source, host repo is ~/agent-fork): install in the brain repo only; agent-fork code doesn't need this hook.
• Brain repo is auto-generated (e.g. by a sync daemon writing to a bucket): skip the hook entirely; gate at the writer instead via import { writeBrainPage } from 'gbrain/brain-writer' (planned in a later release; currently the CLI is the surface).

How it fits into the broader frontmatter pipeline

agent writes a page         git commit                 doctor scan
       ↓                          ↓                          ↓
[source content]   →  [pre-commit hook validates]   →  [frontmatter_integrity check]
       ↓                          ↓                          ↓
  raw file on disk       blocks malformed commits     surfaces existing issues
                                                             ↓
                                                  `gbrain frontmatter validate
                                                   <source-path> --fix`
                                                   (writes .bak backups)

The hook is the write-time gate; doctor is the audit gate; the CLI is the fix tool. They share parseMarkdown(..., {validate:true}) as the single source of truth for what counts as malformed.