Git Guardrails

Git Guardrails

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

What You Get

• PreToolUse hook blocking destructive git operations
• Project-scoped or global installation
• Customizable blocked command patterns
• Verification test command

What Gets Blocked

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

When blocked, the host receives a message explaining why the command is denied.

WRONG: no guardrails, Claude runs destructive commands silently

# The coding agent decides to "clean up" and runs:
git reset --hard HEAD~3   # 3 commits of work gone
git clean -fd             # untracked files deleted
git push --force          # rewrites shared history

CORRECT: hook blocks before execution

$ echo '{"tool_input":{"command":"git push --force"}}' | block-dangerous-git.sh
BLOCKED: git push is not allowed. Ask the user to run it manually.

Setup Steps

1. Identify host and scope -- Codex or Claude Code; project or global.
2. Copy hook script -- bundled at scripts/block-dangerous-git.sh. Put it in the host's project or global hooks directory and make it executable.
3. Add to settings -- see settings-config.md for Codex and Claude Code examples.
4. Customize -- ask if user wants to add/remove patterns from the blocked list
5. Verify -- echo '{"tool_input":{"command":"git push origin main"}}' | <path-to-script> should exit code 2 with BLOCKED message

Reference