Auto Commit AI

Git hook for macOS that generates commit messages from your staged diff using OpenAI's Responses API.

The hook is designed for local use: it keeps your API key out of the script, avoids logging diffs by default, and never blocks a commit if the AI request fails.

• Generates a commit message from git diff --cached.
• Uses OpenAI's current /v1/responses endpoint.
• Uses a concise format: title plus bullet list.
• Reads the OpenAI key from OPENAI_API_KEY or macOS Keychain.
• Skips manual, merge, squash, and amend commits.
• Limits large diffs before sending them to OpenAI.
• Writes Update changes as a fallback if AI generation fails and the commit message is empty.
• Writes diagnostic logs to prepare-commit-msg.log next to the installed hook.
• Does not log diff contents unless explicitly enabled.

• macOS.
• Xcode or Command Line Tools with Swift available through xcrun swift.
• Git 2.x or later.
• OpenAI API key.

Use a global Git hooks directory if you want the hook available in all local repositories.

1. Create a hooks directory:

   mkdir -p ~/.ai-githooks

2. Copy the hook:

   cp prepare-commit-msg ~/.ai-githooks/prepare-commit-msg

3. Make it executable:

   chmod +x ~/.ai-githooks/prepare-commit-msg

4. Configure Git to use that directory:

   git config --global core.hooksPath ~/.ai-githooks

5. Store your API key in macOS Keychain:

   security add-generic-password \
     -a "$USER" \
     -s auto-commit-ai-openai-api-key \
     -w "YOUR_OPENAI_API_KEY" \
     -U

To disable the global hook later:

git config --global --unset core.hooksPath

Use this if you only want the hook in one repository.

cp prepare-commit-msg /path/to/your/repo/.git/hooks/prepare-commit-msg
chmod +x /path/to/your/repo/.git/hooks/prepare-commit-msg

Then configure the API key using either Keychain or OPENAI_API_KEY.

Recommended for normal local use:

security add-generic-password \
  -a "$USER" \
  -s auto-commit-ai-openai-api-key \
  -w "YOUR_OPENAI_API_KEY" \
  -U

Useful for terminal-only workflows:

export OPENAI_API_KEY="YOUR_OPENAI_API_KEY"

For GUI Git clients, environment variables may not be available. Keychain is usually more reliable on macOS.

All configuration is optional and uses environment variables.

1. Stage your changes:

   git add .

2. Commit without providing a message:

   git commit

3. Review or edit the generated message in your Git editor.

The hook skips git commit -m "..." when the message is non-empty so manual messages are respected. Empty messages, including SourceTree's No message placeholder, receive an AI-generated message. It does not skip Git templates, because those are loaded before the editor opens.

The hook writes logs next to the installed script:

cat ~/.ai-githooks/prepare-commit-msg.log

Diff contents are not logged by default. Enable AUTO_COMMIT_AI_LOG_DIFF=true only for temporary debugging.

The staged diff is sent to OpenAI. Do not use this hook for commits containing secrets or code that cannot leave your machine.

The hook limits large diffs, but it does not redact secrets automatically.

auto-commit-ai/
├── prepare-commit-msg
├── README.md
└── LICENSE

Apache License 2.0

Arturo Carretero Calvo - 2026