Git Commit Skill

This skill helps you create well-structured, atomic git commits with properly formatted commit messages.

When to Use This Skill

Use this skill when:

• You need to commit changes to a git repository
• You want to create atomic, logically grouped commits
• You need to follow commit message best practices
• You have multiple changes that should be split into separate commits
• You need to use git partial adds (git add -p) for fine-grained control

Task Overview

Based on the current git status and changes, create a set of logically grouped, atomic commits. Be specific with each grouping, and keep scope minimal. Leverage partial adds to make sure that multiple changes within a single file aren't batched into commits with unrelated changes.

Process

1. Analyze Current State

   • Check git status to see staged and unstaged changes
   • Review git diff to understand what has changed
   • Check recent commits (git log --oneline -20) to understand:
     • Whether the project uses conventional commits (e.g., feat:, fix:, docs:)
     • The project's commit message style and conventions
     • Typical subject line length and formatting patterns

2. Group Changes Logically

   • Identify related changes that should be committed together
   • Separate unrelated changes into different commits
   • Use git add -p for partial adds when a file contains multiple logical changes

3. Create Commits

   • Stage the appropriate changes for each commit
   • Write commit messages following the best practices below
   • Verify each commit is atomic and complete

Commit Message Format Detection

IMPORTANT: Before writing any commits, analyze the recent git history to determine the project's commit style:

• Check for Conventional Commits: Look for patterns like feat:, fix:, docs:, chore:, refactor:, test:, style:, perf:, ci:, build:
• Match the existing style: If 80% or more of recent commits follow conventional commits, use that format
• Be consistent: Match the capitalization, punctuation, and structure of existing commits

Conventional Commits Format

If the project uses conventional commits, follow this structure:

<type>[(optional scope)]: <description>

[optional body]

[optional footer(s)]

Common types:

• feat: A new feature
• fix: A bug fix
• docs: Documentation changes
• style: Code style changes (formatting, missing semicolons, etc.)
• refactor: Code changes that neither fix bugs nor add features
• perf: Performance improvements
• test: Adding or updating tests
• build: Changes to build system or dependencies
• ci: Changes to CI configuration
• chore: Other changes that don't modify src or test files

Examples:

• feat: add user authentication
• fix: resolve null pointer in login handler
• docs: update API documentation
• refactor(auth): simplify token validation logic

Git Commit Message Best Practices

Follow these seven rules for excellent commit messages (adjust for conventional commits if used):

1. Separate subject from body with a blank line - Critical for readability
2. Limit subject line to 50 characters - Forces concise summaries
3. Capitalize the subject line - Consistent formatting
4. Do not end subject line with a period - It's a title, not a sentence
5. Use imperative mood in subject - "Add feature" not "Added feature"
   • Test: Subject should complete "If applied, this commit will _____"
6. Wrap body at 72 characters - Ensures readability in terminals
7. Use body to explain what and why vs. how - Code shows how, commit explains why

Message Structure

<subject: concise summary, imperative, capitalized, no period>

<body: explain the motivation for the change and contrast with previous behavior>

<footer: references to issues, breaking changes, etc.>

Key Principles

• Atomic commits: Each commit should represent one logical change
• Context is king: Explain WHY the change was made, not just what
• Future-proof: Write for someone (including future you) reading this months later
• Consistency: Maintain uniform style across the project

Examples

Good Examples (Traditional Style):

• Refactor subsystem X for readability
• Remove deprecated methods from UserService
• Fix null pointer exception in login handler
• Add user authentication middleware

Good Examples (Conventional Commits):

• feat: add user authentication middleware
• fix: resolve null pointer exception in login handler
• refactor: improve subsystem X readability
• chore: remove deprecated methods from UserService

Bad Examples:

• fixed stuff
• Changes
• wip
• Update file.js
• feat added new feature (incorrect format - missing colon)

Implementation Steps

1. Run git status to see current state
2. Run git diff HEAD to see all changes
3. Run git log --oneline -20 to analyze recent commit style
   • Determine if conventional commits are used (look for type: prefix patterns)
   • Note the typical capitalization and formatting style
   • Identify any project-specific conventions
4. Identify logical groupings of changes
5. For each logical group:
   • Stage the relevant changes (use git add -p if needed)
   • Create a commit with a well-formatted message matching the project's style
   • Verify the commit with git show
6. After all commits, run git status to verify nothing important was missed

Notes

• ALWAYS check recent git history first to determine if conventional commits are used
• Match the project's existing style - consistency is more important than personal preference
• DO NOT push to remote unless explicitly asked
• Always verify authorship and commit details before amending
• Use git add -p for interactive staging when files contain multiple unrelated changes
• Keep commits focused and atomic - one logical change per commit
• If in doubt about whether to use conventional commits, look at the last 20-30 commits for patterns