commit-message

Commit Message Generation

This skill generates clear, conventional commit messages from git diffs by analyzing staged changes and recent commit history.

When to Use This Skill

Use this skill when:

• Writing a commit message for staged changes
• Reviewing what to commit
• Need a well-formatted conventional commit message
• Analyzing git diffs to understand changes

How It Works

1. Analyze staged changes - Run git diff --staged to see what will be committed
2. Review recent commits - Run git log -5 --oneline to understand commit message style
3. Generate message - Create a concise, conventional commit message
4. Return message - Provide the message for use in commit command

Message Format

Follow this strict format:

<type>: <subject>

[optional body]

Type (required)

Choose the most specific type:

• feat: New feature
• fix: Bug fix
• docs: Documentation only
• style: Formatting, missing semicolons, etc.
• refactor: Code restructuring without behavior change
• perf: Performance improvement
• test: Adding or updating tests
• chore: Build process, dependencies, tooling
• ci: CI/CD configuration
• build: Build system or dependencies

Subject (required)

• Present tense (Add, Fix, Update, not Added, Fixed, Updated)
• No period at the end
• 50 characters or less
• Lowercase after the colon
• Describe what changed and why, not how

Body (optional)

• Use only when the subject needs additional context
• Wrap at 72 characters
• Explain motivation and contrast with previous behavior

Guidelines

Subject Rules:

• ✓ feat: add user authentication with JWT
• ✓ fix: prevent race condition in data loader
• ✓ docs: update API endpoint documentation
• ✗ Added user authentication (not conventional format)
• ✗ fix: Fixed the bug (redundant, past tense)
• ✗ Update stuff (too vague)

Be Specific:

• ✓ refactor: extract validation logic to separate module
• ✗ refactor: improve code

Single Responsibility:

• If changes span multiple types, prefer the most significant one
• If truly mixed, consider suggesting multiple commits

Process

1. Run git commands:

   git diff --staged
   git log -5 --oneline
   

2. Analyze the diff:

   • What files changed?
   • What's the nature of changes (new feature, bug fix, refactor)?
   • Is there a clear single purpose?

3. Check commit history:

   • Do they use conventional commits?
   • Any special patterns or conventions?

4. Generate message:

   • Choose the appropriate type
   • Write a concise subject
   • Add body only if needed

5. Return: Provide the message as a code block ready to use

Examples

Example 1: Simple feature

Staged: New login component
Message: feat: add JWT-based login component

Example 2: Bug fix with context

Staged: Fix in error handler
Message: fix: prevent null pointer in async error handler

Adds null check before accessing error.stack property to avoid
crashes when error object is malformed.

Example 3: Refactoring

Staged: Extract functions
Message: refactor: extract database queries to repository layer

Example 4: Documentation

Staged: README updates
Message: docs: add installation instructions for Windows

Key Principles

1. Atomic commits - One logical change per commit
2. Present tense - Always use present tense verbs
3. Be concise - Subject line under 50 chars
4. Be specific - Avoid vague terms like "update", "fix stuff"
5. Conventional format - Always use type prefix
6. No redundancy - Don't repeat information from the diff
7. Focus on why - Explain motivation, not implementation details