Preventing git commit --amend with Claude Code Hooks

Here’s how I prevent git commit --amend using Claude Code’s hook system.

During the commit operation, when the pre-commit hook fails, Claude Code has a tendency to use git commit --amend instead of correcting and retrying git commit. This makes for a messy history, where commits contain unrelated changes.

Hook Configuration

Add this to your Claude Code settings:

"hooks": {
  "PreToolUse": [
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "<repo-path>/.claude/pre_command_hook.py"
        }
      ]
    }
  ]
}

Hook Script

Create .claude/pre_command_hook.py:

#!/usr/bin/env python3
"""
Pre-command hook for Claude Code to prevent git commit --amend
"""
import json
import sys


def main():
    try:
        # Read input from stdin
        input_data = json.load(sys.stdin)

        # Get the command from the tool input
        command = input_data.get("tool_input", {}).get("command", "")

        # Check if it's a git commit command with --amend
        if "git commit" in command and "--amend" in command:
            print("ERROR: git commit --amend is not allowed in this project. Please use regular commits instead.", file=sys.stderr)
            sys.exit(2)  # Block the command

        # Allow all other commands
        sys.exit(0)

    except Exception as e:
        # If there's any error parsing, allow the command to proceed
        print(f"Hook error: {e}", file=sys.stderr)
        sys.exit(0)


if __name__ == "__main__":
    main()

The hook intercepts all Bash commands, checks for git commit --amend, and blocks execution with exit code 2.

Note: Claude Code can generate both the hook configuration and script for you automatically. 🧠