Commit Message Writer

---
name: commit-message-writer
description: "Writes a git commit message from the actual staged diff, focused on why the change was made. Use when the user asks for a commit message, wants to commit, or asks to summarize staged changes."
allowed-tools: Bash(git status:*) Bash(git diff:*) Bash(git log:*)
---

# Commit Message Writer

## Before writing
1. Run `git status --short` to see what is staged.
2. Run `git diff --staged` and read all of it. If nothing is staged, say so and ask; do not guess from unstaged work.
3. Run `git log -n 10 --oneline` to match the repo's existing style (prefixes, tense, casing).

## Format
- Subject: imperative mood, 50 characters or fewer, no trailing period.
- Blank line, then a body wrapped near 72 columns, only if the change needs explaining.
- The body says why: the problem, the reason for this approach, and anything a reviewer might wonder about. The diff already shows what.
- Use a Conventional Commits prefix (`fix:`, `feat:`) only if the recent log does.

## Example
```
Retry webhook delivery on 5xx responses

Partners reported missed events during their deploy windows. A single
failed attempt dropped the event, so retry up to three times with
backoff before giving up.
```

## Never
- Describe changes that are not in the staged diff.
- Restate the diff line by line ("changed X to Y").
- Use vague subjects like "fix bug" or "updates".
- Run `git commit` unless the user asked you to commit.