commit-writer

name	commit-writer
description	Write conventional commit messages from staged diff — type, scope, subject, body, breaking changes

Commit Writer Skill

When to activate

• You have staged changes and need a well-structured commit message
• Writing commit messages across a team that uses Conventional Commits
• Generating commit messages that will feed into automated changelogs
• You want Claude to analyse the diff and propose the right commit type

When NOT to use

• Work in progress / draft commits — use git commit -m "wip" and squash later
• Merge commits — let git generate these
• Revert commits — git revert generates the message automatically

Instructions

Conventional Commits format

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

[body]

[footer]

Types:

Type	When to use
feat	New feature or capability visible to users
fix	Bug fix
docs	Documentation only — no code change
style	Formatting, whitespace — no logic change
refactor	Code restructuring with no behaviour change
perf	Performance improvement
test	Adding or fixing tests
chore	Build, tooling, dependency updates
ci	CI/CD configuration changes
revert	Reverts a previous commit

Rules:

• Subject: imperative mood, lowercase, no full stop, max 72 chars — "add user auth" not "Added user auth"
• Scope: optional, in parentheses — the module, package, or file area affected
• Body: explain why, not what (the diff shows the what)
• Breaking changes: add BREAKING CHANGE: in the footer, or ! after the type (feat!:)

Workflow

Run this before invoking the skill:

git diff --staged   # see what you're about to commit

Then prompt Claude:

Write a conventional commit message for these staged changes:

[paste git diff --staged output, or describe what changed]

Claude will:

1. Identify the primary change type
2. Infer the scope from files changed
3. Draft a subject line (imperative, ≤72 chars)
4. Add a body if the change needs explanation
5. Flag breaking changes if present

Multi-change commits

If the diff contains multiple logical changes, Claude will either:

• Write one commit that covers the primary change (mentioning others in the body)
• Suggest splitting into separate commits with git add -p

Output format

Claude outputs the commit message ready to copy-paste:

git commit -m "feat(auth): add JWT refresh token rotation

Implement sliding session windows by rotating refresh tokens on each use.
Previous tokens are invalidated immediately after rotation.

Closes #234"

Example

Staged diff includes:

• src/auth/tokens.py — new rotate_refresh_token() function
• tests/test_tokens.py — tests for the new function
• CHANGELOG.md — updated

Expected output:

feat(auth): add refresh token rotation

Rotate refresh tokens on each use to implement sliding session windows.
Previous tokens are invalidated immediately, reducing the window for
token theft after a session is compromised.

Closes #234

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