git-commit-composer

Git Commit Composer

Before generating any output, read config/defaults.md and adapt all patterns, imports, and code examples to the user's configured stack.

Process

1. Run git diff --cached to read staged changes. If nothing is staged, run git diff and inform the user to stage changes first.
2. Analyze the diff to determine: what changed, why it changed, and the impact.
3. Classify the change type and generate a commit message following Conventional Commits.
4. If the diff contains multiple unrelated changes, suggest splitting into separate commits.

Commit Message Format

<type>(<scope>): <description>

[optional body]

[optional footer(s)]

### Types

| Type | When to use |
|---|---|
| `feat` | New feature or capability |
| `fix` | Bug fix |
| `refactor` | Code change that neither fixes a bug nor adds a feature |
| `test` | Adding or updating tests |
| `docs` | Documentation changes only |
| `style` | Formatting, semicolons, whitespace (no logic change) |
| `perf` | Performance improvement |
| `chore` | Build, tooling, dependency updates, config changes |
| `ci` | CI/CD configuration changes |
| `build` | Build system or external dependency changes |
| `revert` | Reverts a previous commit |

### Scope

Derive the scope from the primary area of change:

- File/module name: `feat(auth): add JWT refresh token rotation`
- Feature area: `fix(checkout): prevent double charge on retry`
- Layer: `refactor(api): extract validation middleware`

Omit scope if the change spans many unrelated areas.

### Description Rules

- Use imperative mood: "add" not "added" or "adds"
- No capitalized first letter
- No period at the end
- Under 72 characters total (including type and scope)
- Describe what the change does, not what was wrong

**BAD:**

fix: Fixed the bug where users couldn't log in. feat: Added new validation to the form chore: updated dependencies

**GOOD:**

fix(auth): prevent login failure when session cookie is expired feat(form): add email format validation to signup form chore(deps): bump next from 14.1.0 to 14.2.0

### Body

Add a body when the description alone doesn't explain the "why":

fix(api): return 404 instead of 500 for missing resources

Previously, querying a non-existent user threw an unhandled PrismaClientKnownRequestError, resulting in a 500 response. Now the error is caught and mapped to a proper 404.

### Breaking Changes

Use `!` after the type/scope and add a `BREAKING CHANGE` footer:

feat(api)!: change user endpoint response format

BREAKING CHANGE: GET /api/users now returns { data: User[], meta: {...} } instead of a plain User[] array. All clients must update their response parsing.

## Multi-Change Detection

When the diff modifies unrelated areas, suggest splitting:

Suggested Commits

The staged changes contain 3 unrelated modifications. Recommend splitting:

1. feat(auth): add password reset endpoint Files: app/api/auth/reset/route.ts, lib/email.ts

2. fix(ui): correct date format on invoice page Files: components/InvoiceTable.tsx

3. chore(deps): bump zod from 3.22.0 to 3.23.0 Files: package.json, package-lock.json

To split, unstage all and re-stage per commit: git reset HEAD . git add app/api/auth/reset/route.ts lib/email.ts && git commit git add components/InvoiceTable.tsx && git commit git add package.json package-lock.json && git commit

## Dependency Updates

For dependency changes, include the version bump:

chore(deps): bump next from 14.1.0 to 14.2.0 chore(deps-dev): add vitest 2.0.0 and @testing-library/react 16.0.0 fix(deps): pin prisma to 5.19.0 to resolve migration bug

## Output Format

Commit Message

[The generated commit message in a code block]

Analysis

• Type: [type] — [reason for classification]
• Scope: [scope] — [derived from]
• Files changed: [count]
• Insertions/deletions: +[n] / -[n]