Commit Message Generator

Purpose

Generate high-quality commit messages that:

• Follow conventional commit format
• Clearly describe changes
• Provide useful context
• Aid in changelog generation
• Support semantic versioning

When to Use

Invoke this skill when:

• User needs help writing commit messages
• Reviewing staged changes for commit
• Creating standardized team commit messages
• Generating changelog entries
• Teaching commit message best practices

Instructions

Step 1: Analyze the Changes

Examine the git diff to understand:

1. Scope of change: What files/modules affected
2. Type of change: Feature, fix, refactor, docs, etc.
3. Impact: Breaking change or not
4. Why: The reason for the change

Step 2: Determine Commit Type

Choose the appropriate conventional commit type:

• feat: New feature
• fix: Bug fix
• docs: Documentation only
• style: Formatting, missing semicolons, etc.
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Performance improvement
• test: Adding or updating tests
• build: Changes to build system or dependencies
• ci: CI configuration changes
• chore: Other changes that don't modify src or test files
• revert: Reverting a previous commit

Step 3: Identify Scope (Optional)

Determine the scope (area of codebase):

• Component name: auth, api, ui
• Module name: parser, validator
• Feature name: login, checkout

Step 4: Write the Subject Line

Create a subject line that:

• Starts with type and optional scope: type(scope):
• Uses imperative mood: "add" not "added" or "adds"
• Is no longer than 50-72 characters
• Does not end with a period
• Clearly describes WHAT changed

Step 5: Add Body (if needed)

Include a body for complex changes:

• Explain WHY the change was made
• Describe the previous behavior
• Explain the new behavior
• Justify your approach
• Wrap at 72 characters

Step 6: Add Footer (if needed)

Add footer for:

• Breaking changes: BREAKING CHANGE: description
• Issue references: Closes #123, Fixes #456
• Co-authors: Co-authored-by: Name <email>

Examples

Simple Feature Addition

feat(auth): add password reset functionality

Implements password reset via email token. Users can now request
a password reset link that expires after 1 hour.

- Add /reset-password endpoint
- Implement email token generation
- Add reset form UI

Closes #142

Bug Fix

fix(api): resolve null pointer exception in user validation

The validator was not checking for null email values before
processing, causing crashes when users submitted empty forms.

Previous behavior: Crash on null email
New behavior: Return validation error message

Fixes #234

Breaking Change

feat(api)!: change authentication to JWT tokens

BREAKING CHANGE: Session-based auth is replaced with JWT tokens.
Clients must now include 'Authorization: Bearer <token>' header
instead of cookie-based sessions.

Migration guide:
1. Update API client to use Authorization header
2. Remove session cookie handling
3. Implement token refresh logic

Closes #567

Documentation Update

docs(readme): add installation instructions for Windows

Added step-by-step Windows installation guide including:
- Node.js version requirements
- Common PATH configuration issues
- WSL2 setup recommendations

Refactoring

refactor(parser): extract validation logic to separate module

Improves code organization and testability by moving validation
rules into dedicated validator module. No functional changes.

- Create validator.ts module
- Move validation rules from parser.ts
- Update tests to reflect new structure

Conventional Commit Format

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

[optional body]

[optional footer(s)]

Type + Scope Examples

feat(auth): ...
fix(api): ...
docs(readme): ...
style(button): ...
refactor(parser): ...
perf(query): ...
test(auth): ...
build(deps): ...
ci(github): ...
chore(release): ...

Subject Line Templates

Features

• feat: add [feature]
• feat(scope): implement [functionality]
• feat: support [capability]
• feat: enable [feature]

Fixes

• fix: resolve [issue]
• fix(scope): correct [problem]
• fix: prevent [error]
• fix: handle [edge case]

Refactoring

• refactor: extract [component]
• refactor: simplify [logic]
• refactor: reorganize [structure]
• refactor: rename [element] to [new name]

Documentation

• docs: add [documentation]
• docs: update [section]
• docs: improve [content]
• docs: fix typo in [location]

Best Practices

Subject Line

1. Imperative mood: "add" not "added" or "adds"
2. No period: at the end
3. Length: 50 characters ideal, 72 max
4. Capitalize: First letter after type
5. Specific: What changed, not how

Body

1. Wrap: at 72 characters
2. Explain WHY: not what (what is in the diff)
3. Context: Provide background
4. Bullet points: OK for listing changes
5. Blank line: Between subject and body

General

1. Atomic commits: One logical change per commit
2. Test: Ensure tests pass before committing
3. Review: Read the diff before writing message
4. Consistent: Follow team conventions
5. Meaningful: Help future developers (including you)

Common Mistakes to Avoid

1. Vague messages: ❌ "fix stuff" → ✅ "fix: resolve login timeout issue"
2. Past tense: ❌ "added feature" → ✅ "add feature"
3. Too long: ❌ 100+ character subject lines
4. Too generic: ❌ "update code" → ✅ "refactor(auth): extract validation logic"
5. No context: ❌ "fix bug" → ✅ "fix(api): handle null values in user input"

Scope Suggestions by Project Type

Frontend

• ui, component, layout, style, form, nav, header, footer

Backend

• api, auth, db, model, controller, middleware, service

Full Stack

• client, server, shared, config, types, utils

DevOps

• ci, cd, docker, k8s, deploy, monitoring, logging

Templates for Complex Scenarios

Multiple Related Changes

feat(api): add user profile management endpoints

Implements CRUD operations for user profiles including:
- GET /users/:id/profile - Fetch profile
- PUT /users/:id/profile - Update profile
- POST /users/:id/profile/avatar - Upload avatar
- DELETE /users/:id/profile/avatar - Remove avatar

All endpoints include proper authentication and authorization.

Closes #123, #124, #125

Dependency Update

build(deps): upgrade React from 17.0.2 to 18.2.0

Major version update with breaking changes in:
- Concurrent rendering API
- Automatic batching behavior
- SSR changes

Updated all components to use new createRoot API.
All tests passing with new version.

BREAKING CHANGE: Requires Node.js >= 14.0.0

Emergency Hotfix

fix(security): patch XSS vulnerability in comment rendering

SECURITY: User-submitted comments were not properly sanitized,
allowing script injection attacks.

Solution: Implement DOMPurify sanitization on all user content
before rendering.

Severity: High
Affected versions: 1.0.0 - 1.2.3
Fixed in: 1.2.4

CVE-XXXX-XXXXX

Output Format

<type>(<scope>): <subject>

<body paragraph 1>

<body paragraph 2>

<footer>

Related Skills

• git-workflow-guide: For overall git workflows
• changelog-generator: For creating changelogs from commits
• pr-description-generator: For pull request descriptions
• semantic-versioning: For version bumping based on commits