Commitline: commit messages from your diff

Writing commit messages is a chore that leads to lazy labels like "fixed bug" or "updated stuff." This skill automates the process by analyzing your git diff and generating structured, conventional commits.

What it does

• Analyze diffs reads your staged or unstaged changes to understand the logic.
• Enforce conventions maps changes to standard types like feat, fix, refactor, or chore.
• Determine scope identifies the affected module or service such as auth, api, or db.
• Apply constraints ensures subjects are in imperative mood, lowercase, and under 72 characters.
• Write bodies generates optional explanations for non-obvious logic or breaking changes.

How it works

1. Stage your files using git add.
2. Invoke the skill by typing Commitline or commit message?.
3. The agent reads the diff via a bash tool call.
4. It outputs a formatted commit message ready for copy-pasting or direct execution.

Frameworks & tools

The skill requires git and works with any codebase regardless of language. It is optimized for environments with bash tool access like Claude Code or Cursor.

Why this beats prompting it yourself

Generic prompts often produce wordy, conversational, or incorrectly formatted messages. This skill enforces strict Conventional Commits rules and imperative mood by default, saving you from manual linting and overthinking.

Use cases

• Generating clean messages for complex refactors where the scope is broad.
• Documenting breaking changes with the required BREAKING CHANGE: prefix.
• Maintaining a professional git history in team environments with strict CI/CD rules.
• Speeding up the workflow when performing multiple small, atomic commits.

Known limitations

The skill relies on the agent having permission to execute git diff via bash. It assumes a standard Conventional Commits preference unless project rules specify otherwise.