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commit-message-generator skill

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This skill generates conventional commit messages automatically, classifying changes into feat, fix, docs, and more, with clear subject and body.

npx playbooks add skill ntaksh42/agents --skill commit-message-generator

Review the files below or copy the command above to add this skill to your agents.

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SKILL.md

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---
name: commit-message-generator
description: Generate conventional commit messages following best practices. Use when creating structured git commit messages.
---

# Commit Message Generator Skill

高品質なGitコミットメッセージを生成するスキルです。

## 概要

Conventional Commits形式で、明確で一貫性のあるコミットメッセージを自動生成します。

## 主な機能

- **Conventional Commits**: 標準形式
- **自動分類**: feat、fix、docs等
- **詳細説明**: 変更内容の説明
- **Breaking Changes**: 互換性のない変更
- **Issue参照**: 自動リンク

## 使用方法

```
以下の変更内容からコミットメッセージを生成：
- ユーザー認証機能を追加
- JWT トークンを実装
- パスワードハッシュ化
```

## フォーマット

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

<body>

<footer>
```

### Type（必須）

- **feat**: 新機能
- **fix**: バグ修正
- **docs**: ドキュメント
- **style**: コードスタイル（フォーマット等）
- **refactor**: リファクタリング
- **perf**: パフォーマンス改善
- **test**: テスト追加・修正
- **chore**: ビルド、ツール等
- **ci**: CI設定
- **build**: ビルドシステム
- **revert**: 変更の取り消し

### Scope（任意）

変更の範囲（コンポーネント名、モジュール名等）

## 生成例

### 新機能

```
feat(auth): add JWT authentication

Implement JWT-based authentication system with the following features:
- Token generation and validation
- Refresh token mechanism
- Password hashing with bcrypt

Closes #123
```

### バグ修正

```
fix(api): resolve CORS issues in production

Fixed CORS configuration to allow requests from production domain.
Added proper headers and origin validation.

Fixes #456
```

### Breaking Change

```
feat(api)!: change user API response format

BREAKING CHANGE: User API now returns JSON instead of XML.
Migration guide available in docs/migration.md

Before:
```xml
<user>
  <name>John</name>
</user>
```

After:
```json
{
  "user": {
    "name": "John"
  }
}
```

Closes #789
```

### 複数変更

```
feat(users): implement user profile features

- Add profile picture upload
- Add bio and social links fields
- Implement profile visibility settings
- Add email notification preferences

Related to #234, #235
```

### リファクタリング

```
refactor(database): optimize query performance

Refactored user queries to use eager loading instead of N+1 queries.
Reduced database calls from 101 to 2 per request.

Performance improvement: ~90% faster response time
```

### ドキュメント

```
docs(api): update authentication documentation

- Add JWT token usage examples
- Document refresh token flow
- Add error response codes
- Include cURL examples
```

### テスト

```
test(auth): add unit tests for JWT validation

Added comprehensive test coverage for:
- Token generation
- Token validation
- Expired token handling
- Invalid token handling

Coverage: 95%
```

## ベストプラクティス

### 良いコミットメッセージ

```
feat(search): add fuzzy search algorithm

Implemented fuzzy matching for product search using Levenshtein distance.
Users can now find products even with typos.

Closes #567
```

**特徴**:
- 明確なタイプとスコープ
- 簡潔な件名（50文字以内）
- 詳細な本文（なぜ変更したか）
- Issue参照

### 避けるべき例

```
❌ update files
❌ fix bug
❌ WIP
❌ changes
❌ asdf
```

## 自動生成フロー

```bash
# 変更内容を分析
git diff --cached

# AIがコミットメッセージを生成
# 1. 変更ファイルを確認
# 2. 変更タイプを判定（feat/fix/etc）
# 3. スコープを推定
# 4. 変更内容を要約
# 5. Conventional Commits形式で生成
```

## Git Hook統合

```bash
# .git/hooks/prepare-commit-msg
#!/bin/bash

# Staged changesから自動生成
DIFF=$(git diff --cached)

# Claude/AIに送信してメッセージ生成
MESSAGE=$(claude-generate-commit-message "$DIFF")

# コミットメッセージファイルに書き込み
echo "$MESSAGE" > "$1"
```

## バージョン情報

- スキルバージョン: 1.0.0
- 最終更新: 2025-01-22

---

**使用例**:

```
以下の変更からコミットメッセージを生成：

変更ファイル:
- src/auth/jwt.ts (新規)
- src/middleware/auth.ts (新規)
- package.json (jwt依存追加)

変更内容:
- JWT認証を実装
- 認証ミドルウェアを追加
```

**生成されるメッセージ**:
```
feat(auth): implement JWT authentication

Add JWT-based authentication with the following:
- Token generation and validation (jwt.ts)
- Authentication middleware (auth.ts)
- jsonwebtoken dependency

Provides secure stateless authentication for API endpoints.
```

Overview

This skill generates high-quality Git commit messages in the Conventional Commits format. It produces a concise subject, an explanatory body, and an optional footer with issue references or breaking change notes. Use it to enforce consistent, machine-readable commit history across teams.

How this skill works

The generator analyzes staged changes (git diff --cached) and infers the change type (feat, fix, docs, refactor, etc.), probable scope, and a succinct summary. It composes a subject line, a clear body describing why the change was made, and a footer for issue links or BREAKING CHANGE notes. It can be integrated into commit hooks to auto-populate the commit message file.

When to use it

When committing new features or bug fixes to ensure consistency
When preparing commits that must reference issues or breaking changes
When you want concise, 50-char subject lines and informative bodies
When onboarding contributors to maintain a standardized history
When integrating with CI/CD or changelog tooling that relies on Conventional Commits

Best practices

Choose an accurate type (feat, fix, docs, refactor, perf, test, chore, ci, build, revert)
Keep subject under ~50 characters and imperative tense
Include scope to clarify the affected module or component
Explain why in the body and list important implementation details
Add footer lines for issue references (Closes #123) and explicit BREAKING CHANGE notes

Example use cases

Auto-generate a commit message for a JWT authentication feature across multiple files
Create a standardized message for a production bug fix that references an issue
Populate commit text for documentation updates or examples
Produce clear breaking-change notices and migration guidance
Use in a prepare-commit-msg hook to enforce message format before every commit

FAQ

Can this run automatically in a git hook?

Yes. The generator is designed to run inside hooks like prepare-commit-msg to analyze staged diffs and write the suggested message to the commit message file.

How does it determine the scope?

Scope is inferred from file paths and modified modules. It suggests a likely component or directory name, which you can edit before committing.