PRD Example 11: Git Commit Message Generator Skill

Difficulty: Intermediate | Project Type: AI Skill | Time: 4-6 hours

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Overview

What	A Claude Code / Gemini CLI skill that generates conventional commit messages from staged changes
Who	Developers who want consistent, well-formatted commit messages
Why	Saves time and ensures commit messages follow team conventions

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Core Features (MVP)

1. Generate Message: Analyzes git diff --staged and generates a conventional commit message
2. Multiple Options: Provides 3 message options (concise, detailed, with scope)
3. Apply Message: User selects option, skill runs git commit -m "message"
4. Customize Format: Supports conventional commits format (feat:, fix:, docs:, etc.)

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Non-Goals

Will NOT build:

• Integration with issue trackers (Jira, GitHub Issues)
• Multi-commit squashing or rebasing
• Branch name parsing
• Automatic commit without user confirmation
• Commit message history or learning
• Support for non-conventional formats
• GUI or web interface

Will NOT use:

• External APIs beyond the AI tool's native capabilities
• Database or file storage
• Third-party git libraries

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Technical Constraints

Language	TypeScript
Framework	Claude Code Skill format / Gemini CLI compatible
Dependencies	None — uses git CLI directly
Output Format	Conventional commits (type(scope): description)
Testing	Manual testing with sample diffs
Compatibility	Both Claude Code and Gemini CLI

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Success Criteria

• [ ] Skill reads git diff --staged output correctly
• [ ] Generates 3 commit message options
• [ ] Messages follow conventional commits format
• [ ] User can select and execute commit
• [ ] Works in both Claude Code and Gemini CLI
• [ ] Handles empty staging area gracefully

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Implementation Phases

Phase 1: Skill Structure & Diff Reading

Goal: Set up skill and read git diff

Tasks:

1. Create skill directory structure (SKILL.md, prompts/)
2. Define skill trigger phrases ("generate commit", "commit message")
3. Implement git diff reading via bash
4. Parse diff to understand changes

Verification:

# In Claude Code:
claude "generate commit message"
# Skill activates and reads staged changes

# Shows: "Analyzing 3 files changed..."

Deliverables: SKILL.md with basic structure

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Phase 2: Message Generation

Goal: Generate conventional commit options

Tasks:

1. Create prompt for analyzing diff and generating messages
2. Generate 3 options: concise, detailed, with scope
3. Format as conventional commits (feat:, fix:, etc.)
4. Present options to user for selection

Verification:

# After staging a new feature file:
claude "generate commit"

# Output:
# Based on your changes, here are 3 commit message options:
#
# 1. feat: add user authentication module
# 2. feat(auth): add user authentication with JWT support
# 3. feat(auth): implement user authentication
#
#    - Add login/logout endpoints
#    - Implement JWT token generation
#    - Add middleware for protected routes
#
# Which option would you like to use? (1/2/3)

Deliverables: Message generation logic

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Phase 3: Commit Execution & Edge Cases

Goal: Execute commit and handle errors

Tasks:

1. Execute git commit -m "selected message" on user selection
2. Handle empty staging area
3. Handle very large diffs (summarize)
4. Add confirmation before committing

Verification:

# User selects option 2:
claude "use option 2"
# Output: "Committed: feat(auth): add user authentication with JWT support"

# With empty staging area:
claude "generate commit"
# Output: "No staged changes found. Use 'git add' first."

Deliverables: Complete skill with error handling

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Skill File Structure

.claude/skills/commit-message/
├── SKILL.md           # Skill definition and triggers
└── prompts/
    └── analyze-diff.md  # Prompt for diff analysis

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Agent Rules

Always	Ask First	Never
Show diff summary before generating	Before committing	Commit without user confirmation
Provide multiple message options	Before amending previous commit	Push to remote
Follow conventional commits format		Generate messages for unstaged changes
Confirm the selected message		Include sensitive data in messages