Git Guardrails Claude Code

Setup Git Guardrails

Sets up a PreToolUse hook that intercepts and blocks dangerous git commands before Claude executes them.

What Gets Blocked

• git push (all variants including --force)
• git reset --hard
• git clean -f / git clean -fd / git clean -xdf
• git branch -D / git branch --delete --force
• git checkout . / git checkout -- . / git restore . / git restore --staged .

The script strips git's global options before matching, so git -C <path> push, git -c <key>=<val> push and git --git-dir=… --work-tree=… push are blocked too.

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

Limits

Matching is substring-based on the command text, so it over-blocks (a command that merely mentions git push is refused) and it cannot see through eval, a shell variable, or a script the command invokes. Treat it as a seatbelt against accidents, not as a security boundary.

Requires

jq, on the PATH of every environment the hook runs in — Claude Code does not bundle it, and the global install in step 1 puts the hook in devcontainers and CI images too. If jq is missing or the payload does not parse, the script exits 2 (blocks) rather than silently permitting.

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

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):

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

Global (~/.claude/settings.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 the 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 a quick test:

echo '{"tool_input":{"command":"git push origin main"}}' | <path-to-script>
echo '{"tool_input":{"command":"git -C /tmp push origin main"}}' | <path-to-script>
echo '{}' | <path-to-script>

All three should exit with code 2 and print a BLOCKED message to stderr — the last one confirms the hook fails closed on a payload it cannot read.