Changelog Generator

---
name: changelog-gen
description: |
  Trigger when the user asks to generate a CHANGELOG, produce release notes
  from git history, or summarize commits. Phrases: "CHANGELOG", "release notes",
  "what changed", "summarize commits", "since last release".
allowed-tools:
  - Read
  - Write
  - Bash(git log *)
  - Bash(git tag *)
  - Bash(git diff *)
---

# Changelog Generator

Produce a CHANGELOG.md entry from git history between two refs. Follow
Keep a Changelog conventions: Added, Changed, Fixed, Removed, Deprecated,
Security.

## Prerequisites

- Git repo with a history
- Commit messages follow some convention (conventional-commits preferred)

## Steps

1. **Determine the range.** Default to "last tag .. HEAD". Let the user override:

   ```bash
   PREV=$(git describe --tags --abbrev=0)
   git log --pretty=format:"%s" $PREV..HEAD
   ```

2. **Bucket commits.** Use conventional-commit prefixes when present:
   - `feat:` -> Added
   - `fix:` -> Fixed
   - `refactor:` -> Changed
   - `perf:` -> Changed
   - `docs:`, `chore:`, `test:` -> usually omitted unless user-facing
   - `BREAKING CHANGE` or `!:` -> Changed with prominent callout

3. **Rewrite commit messages as user-facing bullets.** Commit message:
   `fix(auth): handle expired JWT without crash`
   becomes:
   - Fixed a crash when the JWT token was expired.

4. **Prepend to CHANGELOG.md** under a new version heading:

   ```markdown
   ## [1.4.0] - 2026-04-23

   ### Added
   - Magic-link sign-in as an alternative to password.

   ### Fixed
   - Expired JWT no longer crashes the auth middleware.
   ```

5. **Skip noise.** Merge commits, revert-only chains, CI tweaks, and formatter
   runs do not belong in a user-facing changelog.

## Format rules

- Use ISO dates.
- Group by category, order alphabetically within a category.
- Link to PRs or issues when IDs are in commit messages.
- Keep entries one line each; the changelog is a reference, not prose.

## Output

- Updated `CHANGELOG.md` with the new version block prepended
- Suggested version bump (major/minor/patch) based on commit types
- List of commits intentionally skipped as noise