generating-conventional-commits

name	generating-conventional-commits
description	Generates conventional commit messages from git diffs. Use when the user asks about writing commit messages, reviewing staged changes, committing code, or needs help with git commits.
metadata	{"author":"aasanchez"}

Generating Conventional Commits

This Skill teaches Claude to generate properly formatted conventional commit messages that follow the Conventional Commits specification (https://www.conventionalcommits.org/).

Overview

Conventional Commits is a specification for adding human and machine-readable meaning to commit messages. The format correlates with Semantic Versioning (SemVer):

• feat → MINOR version bump
• fix → PATCH version bump
• BREAKING CHANGE or ! → MAJOR version bump

Commit Message Structure

type(scope): subject

[optional body]

[optional footer(s)]
```text

### Type (required)

The commit type communicates the intent of the change:

- **feat**: A new feature for the user (not a new feature for build script)
- **fix**: A bug fix for the user (not a fix to a build script)
- **docs**: Documentation only changes (README, comments, JSDoc)
- **style**: Code style changes (formatting, missing semicolons, whitespace)
- **refactor**: Code changes that neither fix bugs nor add features
- **perf**: Code changes that improve performance
- **test**: Adding missing tests or correcting existing tests
- **chore**: Changes to build process, dependencies, or auxiliary tools
- **ci**: Changes to CI configuration files and scripts
- **build**: Changes to build system or external dependencies

### Scope (optional)

A scope provides additional contextual information about the affected area:

- Noun describing a section of the codebase
- Enclosed in parentheses: `feat(parser): add support for arrays`
- Examples: `api`, `ui`, `auth`, `database`, `core`, `utils`

### Subject (required)

The subject is a brief description of the change:

**Rules**:

- Maximum 50 characters (hard limit: 72)
- Use imperative, present tense: "change" not "changed" nor "changes"
- Don't capitalize the first letter (unless it's a proper noun)
- No period (.) at the end
- Be specific and descriptive

**Good examples**:

- `add user authentication`
- `fix memory leak in event handler`
- `update dependencies to latest versions`

**Bad examples**:

- `Added user authentication` (wrong tense)
- `Fix bug` (not specific)
- `Updated the dependencies.` (has period, capitalized)

### Body (optional)

Use the body to explain:

- **What** changed
- **Why** it changed (motivation)
- **Context** for the change

**Rules**:

- Separate from subject with a blank line
- Wrap at 72 characters
- Use multiple paragraphs if needed
- Use bullet points with `-` or `*` for lists
- Explain what and why, not how (code shows how)

### Footer (optional)

Footers provide metadata:

**Issue references**:

- `Closes #123` - Closes an issue
- `Fixes #456` - Fixes a bug report
- `Refs #789` - References an issue
- Can reference multiple: `Closes #123, #456`

**Breaking changes**:

- `BREAKING CHANGE: description of the breaking change`
- Must be in all caps
- Should explain migration path

## Breaking Changes Notation

Breaking changes can be indicated in two ways:

1. **Append `!` before the colon**:

   ```text
   feat(api)!: change authentication response format

1. Use footer:

   feat(api): change authentication response format
   
   BREAKING CHANGE: The /auth endpoint now returns tokens in a nested
   `credentials` object instead of at the root level.
   

Instructions for Generating Commits

When the user asks you to write a commit message or create a commit:

Step 1: Detect JIRA Ticket from Branch

Run git branch --show-current to get the current branch name:

git branch --show-current

Check if the branch name contains a JIRA ticket ID using this pattern: [A-Z][A-Z0-9_]{1,9}-\d+

JIRA ticket format rules:

• Starts with an uppercase letter (A-Z)
• Followed by 1-9 additional characters: uppercase letters (A-Z), digits (0-9), or underscores (_)
• Hyphen separator (-)
• Ends with one or more digits (\d+)

Valid examples: ABC-123, PROJECT-456, JIRA-1, MY_PROJ-789, A1B2-99

Common branch patterns that contain JIRA tickets:

• ABC-123-feature-description
• feature/PROJ-456-add-login
• bugfix/FIX-789-correct-validation
• JIRA-1-initial-setup

If a JIRA ticket is detected, save it to prepend to the commit message.

Step 2: Examine the Changes

Run git diff --staged to understand what will be committed:

git diff --staged

If nothing is staged:

• Inform the user
• Suggest using git add <files> first
• Optionally show git status to see untracked/modified files

Step 3: Analyze the Changes

Determine:

1. Primary intent: What is the main purpose? (feature, fix, refactor, etc.)
2. Affected area: Which component or module is impacted? (for scope)
3. Complexity: Does this need a body to explain?
4. Breaking changes: Does this break existing functionality?
5. Related issues: Are there issue numbers to reference?

Step 4: Choose the Type

Select the most appropriate type:

• If adding new user-facing functionality → feat
• If fixing a user-facing bug → fix
• If only changing documentation → docs
• If only formatting/style → style
• If restructuring without changing behavior → refactor
• If improving performance → perf
• If only changing tests → test
• If updating dependencies or tooling → chore

Note: When multiple types apply, choose the most significant one from the user's perspective.

Step 5: Determine Scope

Ask yourself:

• What component/module is affected?
• Is there a clear boundary in the codebase?
• Would scope add useful context?

Skip scope if:

• Changes affect multiple unrelated areas
• The project is small and scope adds no value
• You're unsure what scope to use

Common scopes by project type:

• Web apps: api, ui, auth, database, middleware
• Libraries: core, utils, parser, renderer
• CLI tools: cli, commands, config

Step 6: Write the Subject

Craft a concise, imperative description:

Formula: [what you're doing] [to what]

Examples:

• add password reset functionality
• fix null pointer in user profile handler
• update React to version 18
• refactor authentication middleware

Step 7: Add Body (if needed)

Add a body when:

• The change is complex or non-obvious
• You need to explain the motivation
• Multiple files or components are affected
• Future developers might wonder "why?"

Skip the body for:

• Simple, self-explanatory changes
• Obvious bug fixes
• Routine updates

Step 8: Add Footer (if applicable)

Include footer for:

• Issue references: Closes #123
• Breaking changes: BREAKING CHANGE: description
• Multiple related issues: Refs #123, #456

Step 9: Review and Present

Before presenting:

1. Check length: Subject ≤ 50 chars (preferably, not including JIRA ticket)
2. Check grammar: Imperative mood, no period
3. Check clarity: Is it specific and clear?
4. Check completeness: All relevant info included?
5. JIRA ticket: If detected, ensure it's ONLY in the subject line prefix

Present the message to the user.

If JIRA ticket was detected in Step 1:

[JIRA-TICKET] type(scope): subject

body (if any)

footer (if any)

If no JIRA ticket was detected:

type(scope): subject

body (if any)

footer (if any)

CRITICAL: The JIRA ticket must ONLY appear at the beginning of the subject line in square brackets. Do NOT mention the JIRA ticket anywhere else in the commit message:

• ❌ Do NOT add it to the body
• ❌ Do NOT add it to the footer
• ❌ Do NOT use "Closes JIRA-123" or "Refs JIRA-123"
• ❌ Do NOT mention it in any other way

Explain your reasoning:

• Why you chose this type
• Why you included/excluded scope
• If JIRA ticket detected, mention which branch it came from
• Any important considerations

Ask for confirmation before executing git commit.

Step 10: Execute Commit (with approval)

Only after user confirms:

If JIRA ticket was detected:

git commit -m "$(cat <<'EOF'
[JIRA-TICKET] type(scope): subject

body

footer
EOF
)"

If no JIRA ticket:

git commit -m "$(cat <<'EOF'
type(scope): subject

body

footer
EOF
)"

Then confirm success with git log -1 or git show HEAD.

Examples

See examples.md for detailed examples covering various scenarios.

Best Practices

1. Atomic commits: One logical change per commit
2. Present tense: "add feature" not "added feature"
3. Imperative mood: Commands, not descriptions
4. Focused scope: Narrow, well-defined changes
5. Meaningful subjects: Specific and descriptive
6. Explanatory bodies: For complex changes
7. Referenced issues: Always link related issues
8. Breaking changes: Always document in footer

Common Pitfalls to Avoid

• Don't use vague subjects like "fix bug" or "update code"
• Don't mix multiple unrelated changes in one commit
• Don't forget to note breaking changes
• Don't use past tense or continuous tense
• Don't exceed 72 characters in subject line
• Don't add periods to subject lines
• Don't capitalize subject line (except proper nouns)

Additional Resources

• Conventional Commits Specification
• Semantic Versioning
• How to Write a Git Commit Message

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