---
name: git-guardrails-claude-code
description: Set up Claude Code hooks to block dangerous git commands (push, reset --hard, clean, branch -D, etc.) before they execute. Use when user wants to prevent destructive git operations, add git safety hooks, or block git push/reset in Claude Code.
---

# Setup Git Guardrails

Sets up a PreToolUse hook that inspects direct Git commands before Claude executes them. It requires Bash and Python 3; missing Python or invalid input blocks the command with exit code 2.

## What Gets Blocked

- Direct `git push` commands, including force flags, ordinary global options, and shell command separators
- `git reset --hard`
- `git clean -f` / `git clean -fd`
- `git branch -D`
- `git checkout .` / `git restore .`

When blocked, Claude sees a message telling it that it does not have authority to access these commands.

This is a conservative command guard, not a shell sandbox. It does not evaluate aliases, shell expansion, or commands hidden in scripts. Unsupported Git global options require manual inspection, and literal Git tokens in arguments can also be blocked. Keep execution permissions enforced by the host.

## Steps

### 1. Ask scope

Ask the user: install for **this project only** (`.claude/settings.json`) or **all projects** (`~/.claude/settings.json`)?

### 2. Copy the hook script

The bundled script is at: [scripts/block-dangerous-git.sh](scripts/block-dangerous-git.sh)

Copy it to the target location based on scope:

- **Project**: `.claude/hooks/block-dangerous-git.sh`
- **Global**: `~/.claude/hooks/block-dangerous-git.sh`

Make it executable with `chmod +x`.

### 3. Add hook to settings

Add to the appropriate settings file:

**Project** (`.claude/settings.json`):

```json
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/block-dangerous-git.sh"
          }
        ]
      }
    ]
  }
}
```

**Global** (`~/.claude/settings.json`):

```json
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "~/.claude/hooks/block-dangerous-git.sh"
          }
        ]
      }
    ]
  }
}
```

If the settings file already exists, merge the hook into existing `hooks.PreToolUse` array — don't overwrite other settings.

### 4. Ask about customization

Ask if user wants to add or remove any patterns from the blocked list. Edit the copied script accordingly.

### 5. Verify

Run the bundled checks; every command is an inert input string:

```bash
python3 scripts/test_guardrail.py
```

Then test the installed copy:

```bash
echo '{"tool_input":{"command":"git push origin main"}}' | <path-to-script>
```

Should exit with code 2 and print a BLOCKED message to stderr.