Clean Commits

Overview

Every commit is atomic, descriptive, and leaves code in a working state.

Core principle: Anyone should be able to checkout any commit and have working code.

Announce at use: "I'm committing with a descriptive message following clean-commits standards."

Commit Message Format

Structure

[type](scope): Short description (max 72 chars)

[Optional body - what and why, not how]

[Optional footer - issue references, breaking changes]

Refs: #[ISSUE_NUMBER]

Types

Type	Use For
feat	New feature
fix	Bug fix
docs	Documentation only
style	Formatting, no code change
refactor	Code restructuring
test	Adding/fixing tests
chore	Maintenance, dependencies

Examples

feat(auth): Add user registration endpoint

Implement POST /api/users/register with email validation,
password hashing, and duplicate detection.

- Validates email format and uniqueness
- Hashes password with bcrypt
- Returns user object without password

Refs: #123

fix(auth): Prevent redirect loop on expired session

Session expiry was triggering redirect to login, which
checked session, found expired, and redirected again.

Now clears session cookie before redirecting.

Refs: #456

test(auth): Add integration tests for registration

Cover success case, duplicate email, invalid format,
and weak password scenarios.

Refs: #123

Atomic Commits

What Makes a Commit Atomic

Atomic	Not Atomic
One logical change	Multiple unrelated changes
Passes all tests	Breaks tests
Complete feature slice	Half-implemented feature
Can be reverted cleanly	Reverts would break things

Signs of Non-Atomic Commits

• Commit message uses "and" to describe multiple things
• Diff includes unrelated files
• Some tests fail after commit
• "WIP" in commit message

Splitting Large Changes

If you have multiple changes, commit them separately:

# Stage specific files
git add src/auth/register.ts
git add src/auth/register.test.ts
git commit -m "feat(auth): Add registration endpoint"

# Stage next logical unit
git add src/auth/login.ts
git add src/auth/login.test.ts
git commit -m "feat(auth): Add login endpoint"

Working State Requirement

Every commit must leave the codebase in a state where:

• All tests pass
• Build succeeds
• Application runs
• No TypeScript errors
• No linting errors

Before committing:

# Run tests
pnpm test

# Check build
pnpm build

# Check types
pnpm typecheck

# Check lint
pnpm lint

If any fail, fix before committing.

Commit Frequency

Commit Often

• After each passing test in TDD cycle
• After each refactoring step
• After completing a logical unit

Don't Wait Too Long

Too Infrequent	Just Right
"Implement entire feature"	"Add user model"
"Fix all bugs"	"Fix session expiry redirect"
"Update everything"	"Update auth dependencies"

Small is Good

Smaller commits are:

• Easier to review
• Easier to revert
• Easier to bisect
• Easier to understand

The Commit Process

1. Stage Selectively

# Review what changed
git diff

# Stage specific files
git add [specific files]

# Or stage interactively
git add -p

2. Review Staged Changes

# See what will be committed
git diff --staged

3. Write Descriptive Message

# Short message (if simple)
git commit -m "fix(auth): Handle null user in session check"

# Long message (if complex)
git commit
# Opens editor for full message

4. Verify After Commit

# Check commit looks right
git show --stat

# Verify tests still pass
pnpm test

Commit Message Body

When to include a body:

• Why the change was made (not just what)
• Context that isn't obvious from code
• Trade-offs or alternatives considered
• Breaking changes if any

Body Examples

refactor(api): Extract validation middleware

Validation logic was duplicated across 12 endpoints.
Extracted to reusable middleware that can be composed.

Alternative considered: validation library.
Rejected because our rules are domain-specific.

fix(data): Use optimistic locking for updates

Race condition was causing lost updates when two users
edited the same record simultaneously.

BREAKING CHANGE: Update operations now require
version field in request body.

Issue References

Always reference the issue:

# In commit message
Refs: #123

# Or if commit closes the issue
Closes: #123

Amending Commits

When to Amend

• Typo in message (if not pushed)
• Forgot to stage a file (if not pushed)

# Amend last commit (before push only!)
git add forgotten-file.ts
git commit --amend

When NOT to Amend

• After pushing to remote
• Changing commits others have based work on

Revert, Don't Delete

If a commit was wrong:

# Create a new commit that undoes the change
git revert [commit-sha]

# DON'T rewrite history on shared branches
# DON'T force push to fix mistakes

Checklist

Before each commit:

• Tests pass
• Build succeeds
• Change is atomic (one logical unit)
• Message follows format
• Message describes why, not just what
• Issue is referenced
• No "WIP" or placeholder messages

Integration

This skill is called by:

• issue-driven-development - Throughout development
• pr-creation - Before creating PR

This skill enforces:

• Reviewable history
• Revertible changes
• Clear project narrative