commit-message-storyteller

Commit Message Storyteller

Transforms raw git diffs and change descriptions into clear, story-driven commit messages that follow the Conventional Commits specification. Instead of "update file.js", you get messages that communicate intent, context, and impact.

When to Use This Skill

User says "write a commit message", "help me commit", or "generate a commit"
User pastes a git diff or describes code changes
User says "what should I commit this as?" or "summarize my diff"
User wants better commit history for their team or open-source project
User is preparing a pull request and wants meaningful commit messages

Prerequisites

Have at least one of the following ready:

Output from git diff or git diff --staged
A description of what you changed and why
A list of modified files

How It Works

Step 1: Gather the Change Context

Ask the user (or infer from the diff) for:

What changed — files, functions, logic affected
Why it changed — bug fix, new feature, refactor, performance, etc.
Who/what triggered it — issue number, user request, tech debt, etc.

If the user provides a raw git diff, extract this context automatically from the diff.

Step 2: Identify the Commit Type

Map the change to a Conventional Commits type using this guide:

Type	Use When
`feat`	A new feature or capability is added
`fix`	A bug or incorrect behavior is corrected
`refactor`	Code restructured without changing behavior
`perf`	A change that improves performance
`docs`	Documentation only changes
`style`	Formatting, whitespace, missing semicolons (no logic change)
`test`	Adding or updating tests
`chore`	Build process, dependency updates, config changes
`ci`	CI/CD pipeline changes
`revert`	Reverting a previous commit

See references/conventional-commits-guide.md for detailed examples.

Step 3: Write the Commit Message

Follow this structure:

<type>(<optional scope>): <short imperative summary>

<body — the story: why this change was made, what problem it solves>

<footer — issue refs, breaking change notices>

Rules for Each Part

Subject line (first line):

Use imperative mood: "add", "fix", "remove" — not "added" or "fixes"
Max 72 characters
No period at the end
Lowercase after the colon

Body (the story):

Explain the why, not the what (the diff already shows the what)
Describe the problem that existed before this change
Mention any alternatives considered if relevant
Keep lines under 100 characters
Separate from subject with a blank line

Footer:

Reference issues: Closes #123, Fixes #456, Refs #789
Mark breaking changes: BREAKING CHANGE: <description>

Step 4: Generate Output

Produce the commit message in a copyable code block, followed by a one-line plain-English explanation of the story you told.

Example output:

fix(auth): prevent token refresh loop on expired sessions

When a user's session expired mid-request, the auth middleware was
triggering a token refresh, which itself failed validation and triggered
another refresh — causing an infinite retry loop that crashed the app.

This adds a recursion guard flag that aborts the refresh cycle if a
refresh is already in progress, returning a clean 401 instead.

Closes #312

Story told: A silent infinite loop on session expiry was crashing the app; this stops the cycle early and returns a clean error.

Multiple Commits from One Diff

If the diff contains logically separate changes, split them into multiple commit messages and tell the user. Use this heuristic:

Different files with unrelated purposes → likely separate commits
Same file but distinct concerns (e.g., bug fix + refactor) → suggest splitting
Everything tightly coupled → one commit is fine

Edge Cases

Situation	How to Handle
User provides no context beyond a diff	Infer type and scope from file names and changed symbols
Changes span many files with no clear theme	Ask: "Is this one logical change, or multiple?"
Breaking change detected	Add `BREAKING CHANGE:` footer automatically
User says "keep it short"	Omit body, just write a strong subject line
No issue number available	Omit the footer entirely

Quick Reference

# Get your staged diff to paste into Copilot
git diff

See references/conventional-commits-guide.md for type examples and scope guidelines.