gitleash

Keep your AI coding agent on a leash. A zero-config git guardrail that stops reckless agent commits — huge diffs, deleted tests, hardcoded secrets, CI edits — and force-pushes to main before they land. Works with Claude Code, Cursor, aider, Codex, or a human on a bad day. It's just a git hook, so it fires no matter who (or what) made the change.

Why

You hand an AI agent your repo and walk away. It comes back having deleted the failing test instead of fixing it, regenerated your lockfile, hardcoded an API key, and rewritten 600 lines across 30 files — all staged, ready to commit.

gitleash is a pre-commit tripwire tuned for exactly that. When a staged commit crosses a danger line, it stops the commit and tells you why. Nothing is blocked silently; every block is one env var away from an override.

Quick start

npm i -g gitleash        # or: npm i -D gitleash
cd your-repo
gitleash install         # writes pre-commit + pre-push hooks (once per repo)

That's it. The next time an agent tries a reckless commit, it gets stopped:

gitleash — 2 blocking issues, 0 warnings

  ✖ protect-tests  Test file deleted: app.test.ts. Agents sometimes "fix" failing
                   tests by removing them — confirm this is intentional.
  ✖ secrets        Possible AWS access key in the staged changes.

Commit blocked. If this is intentional, override with:
  GITLEASH_OK=1 git commit ...      (or: git commit --no-verify)

The default rules (tuned for autonomous agents)

Rule	Severity	Fires when
big-diff	block	> 400 changed lines, or > 25 changed files, in one commit
protect-tests	block	a test file is deleted
protect-ci	block	a .github/workflows/* or other CI file changes
secrets	block	staged content matches a secret pattern (AWS/GitHub/OpenAI keys, private keys, hardcoded credentials)
lockfile-drift	warn	a lockfile changes without its package.json
protected-branch	warn	you commit directly to main / master
force-push	block	a force-push (history rewrite) to a protected branch — via the pre-push hook
protected-branch-push	block	deleting a protected branch — via the pre-push hook

Blocks stop the commit (or push); warnings just print. Auto-generated files (lockfiles, bundles, dist/) don't count toward big-diff. Every threshold and severity is configurable.

Configuration

Zero config works out of the box. To tune, run gitleash init and edit .gitleash.json (or add a gitleash key to package.json):

{
  "maxLines": 400,
  "maxFiles": 25,
  "protectTests": true,
  "protectCi": true,
  "scanSecrets": true,
  "warnLockfileDrift": true,
  "protectedBranches": ["main", "master"],
  "disabledRules": [],
  "ruleSeverity": { "protect-ci": "warn" }
}

disabledRules turns rules off entirely; ruleSeverity re-grades a rule (e.g. downgrade protect-ci from block to warn) instead of disabling it.

Commands

Command	What it does
gitleash install	Install the pre-commit + pre-push hooks (coexists with existing hooks)
gitleash check	Check the staged diff — what the pre-commit hook runs
gitleash check --range main..HEAD	Check a commit range instead (handy in CI)
gitleash check --json	Emit findings as JSON (for CI dashboards)
gitleash init	Write a .gitleash.json you can tune
gitleash uninstall	Remove the hooks

Use in CI

# .github/workflows/gitleash.yml
- run: npx gitleash check --range origin/main...HEAD

How it works

gitleash install writes a pre-commit hook (runs gitleash check) and a pre-push hook (runs gitleash pre-push). On commit, gitleash reads the staged diff (git diff --cached), runs the rules, and exits non-zero if anything blocks — which aborts the commit. On push, it inspects the refs git feeds the hook and blocks force-pushes / deletions of protected branches. If a hook already exists, gitleash appends its block so the two coexist.

It never phones home, never uploads your code, and adds no runtime dependency to your project beyond git itself.

Overriding

A block is a speed bump, not a wall. When you've reviewed the change and it's fine:

GITLEASH_OK=1 git commit -m "..."   # gitleash allows it and notes the override
git commit --no-verify -m "..."     # skips all git hooks entirely

To silence a secret false-positive on a single line, mark it inline — the rest of the commit is still checked:

const publishableKey = "pk_live_notreallyasecret"; // gitleash-allow

The big-diff rule never fires on a repo's first commit (bootstrapping a project is legitimately large).

Origin story

The very first time I pushed gitleash to GitHub, the push was rejected — GitHub's own secret scanner found two "API keys" in the test fixtures and blocked me. They were fake, of course, but real-looking enough to trip the scanner.

Which is exactly the point. A check that catches secrets — and huge diffs, deleted tests, force-pushes — is something you want on your own machine, before the push, for every rule, not only for secrets and not only when a server happens to notice. gitleash is that check: local, zero-config, firing on every commit and push.

Requirements

• Node ≥ 18
• git on your PATH

Changelog

See CHANGELOG.md.

License

MIT