Changelog Generator Skill

Auto-generate changelogs from git history using conventional commit format. Parses commit messages, groups them by type and scope, and produces a CHANGELOG.md following the Keep a Changelog standard.

When to Use

• A release is being prepared and a changelog is needed
• User asks to generate or update the CHANGELOG.md
• A version tag is about to be created
• Stakeholders need a summary of what changed since the last release
• CI/CD pipeline needs automated release notes

Patterns

Conventional Commit Parsing

Map commit prefixes to changelog sections:

Commit Prefix	Changelog Section	Semver Impact
feat	Added	minor
fix	Fixed	patch
refactor	Changed	patch
perf	Changed	patch
docs	Documentation	none
security	Security	patch
BREAKING CHANGE	Breaking Changes	major
deprecate	Deprecated	minor
revert	Reverted	patch

Commits with chore, ci, test, or build prefixes are excluded from user-facing changelogs.

Extract Commits Since Last Tag

# Get the latest tag
LAST_TAG=$(git describe --tags --abbrev=0 2>/dev/null || echo "")

# List commits since that tag (or all commits if no tag exists)
if [ -n "$LAST_TAG" ]; then
  git log "${LAST_TAG}..HEAD" --pretty=format:"%h|%s|%an|%ad" --date=short
else
  git log --pretty=format:"%h|%s|%an|%ad" --date=short
fi

Grouping by Scope

When the project is a monorepo, group entries by scope derived from the conventional commit:

feat(core-service): add project archiving endpoint
fix(ai-service): handle timeout on large inference requests
feat(web): add dark mode toggle to settings page
fix(mobile): correct bottom nav badge count on iOS

This produces a changelog organized by service:

### Core Service
- **Added:** Project archiving endpoint (#142)

### AI Service
- **Fixed:** Handle timeout on large inference requests (#156)

### Web
- **Added:** Dark mode toggle to settings page (#161)

### Mobile
- **Fixed:** Correct bottom nav badge count on iOS (#158)

Version Numbering (Semver)

Determine the next version automatically:

# If any commit contains "BREAKING CHANGE" or has a "!" after the type → major bump
# If any commit starts with "feat" → minor bump
# Otherwise → patch bump

Example logic:

COMMITS=$(git log "${LAST_TAG}..HEAD" --pretty=format:"%s")

if echo "$COMMITS" | grep -qE "^.*!:|BREAKING CHANGE"; then
  BUMP="major"
elif echo "$COMMITS" | grep -qE "^feat"; then
  BUMP="minor"
else
  BUMP="patch"
fi

CHANGELOG.md Template (Keep a Changelog)

# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [1.2.0] - 2026-03-14

### Added
- Project archiving endpoint with soft-delete support (#142)
- Dark mode toggle to settings page (#161)

### Fixed
- Handle timeout on large AI inference requests (#156)
- Correct bottom nav badge count on iOS (#158)

### Changed
- Refactor user authentication flow to use refresh token rotation (#149)

### Security
- Upgrade jsonwebtoken to patch CVE-2026-XXXX (#163)

## [1.1.0] - 2026-02-28
...

Linking to Commits and PRs

Always include the short hash or PR number so readers can trace changes:

- **Added:** User profile avatars ([#134](https://github.com/org/repo/pull/134))
- **Fixed:** Race condition in queue consumer (`a1b2c3d`)

Anti-patterns

• Manual changelogs — hand-writing entries leads to drift and missing items; always generate from git history
• No version tags — without tags there is no anchor for "since last release"; tag every release
• Mixing unrelated changes in one release — prefer single-responsibility releases; if scope is too broad, split the release
• Including internal chores — chore, ci, test commits clutter user-facing changelogs; filter them out
• No PR or commit references — entries without traceability make debugging regressions harder
• Inconsistent date format — always use ISO 8601 (YYYY-MM-DD)

Checklist

• All commits since the last tag follow conventional commit format
• Commits are parsed and grouped into the correct changelog sections
• Version bump is calculated from commit types (major/minor/patch)
• Entries are grouped by scope (service) in monorepo projects
• Each entry includes a PR number or commit hash for traceability
• chore, ci, test, and build commits are excluded
• CHANGELOG.md follows Keep a Changelog format
• Date uses ISO 8601 format
• New version is prepended (not appended) to the changelog
• A git tag is created for the new version after the changelog is finalized