name: changelog description: "Generate changelogs from git history. Use when the user asks to create a changelog, release notes, or summarize changes between tags, branches, or date ranges. Triggers on 'changelog', 'release notes', 'what changed', 'diff summary'."

Changelog Generator

Generate structured changelogs from git commit history using conventional commits.

Usage

/changelog                          # since last tag
/changelog v1.2.0..v1.3.0          # between tags
/changelog --since="2 weeks ago"    # date range
/changelog main..feature-branch     # branch diff

Workflow

Step 1: Determine Range

Parse user input to determine the git range:

# Default: last tag to HEAD
LAST_TAG=$(git describe --tags --abbrev=0 2>/dev/null || echo "")
if [ -n "$LAST_TAG" ]; then
  RANGE="$LAST_TAG..HEAD"
else
  RANGE="HEAD~50..HEAD"  # fallback: last 50 commits
fi

# User-specified range
RANGE="v1.2.0..v1.3.0"

# Date-based
git log --after="2025-01-01" --before="2025-02-01" --oneline

Step 2: Extract Commits

# Get conventional commit log with authors
git log $RANGE --pretty=format:"%h|%s|%an|%ad" --date=short

# Include PR numbers if available
git log $RANGE --pretty=format:"%h|%s|%an" --grep="(#[0-9]*)"

Step 3: Categorize

Group commits by conventional commit prefix:

Commits without conventional prefix: categorize by analyzing the message.

Step 4: Enrich

For each commit, optionally:

• Link PR numbers: #123 -> [#123](https://github.com/org/repo/pull/123)
• Link issues: fixes #456 -> [#456](https://github.com/org/repo/issues/456)
• Get PR title if commit message is a merge commit
• Attribute contributors

Detect repo origin for links:

REMOTE_URL=$(git remote get-url origin 2>/dev/null)

Step 5: Generate Output

Default format: Markdown

# Changelog

## [v1.3.0] - 2025-02-05

### Breaking Changes
- Description of breaking change (#PR)

### Features
- Add user authentication flow (#123) - @author
- Support batch processing for imports (#124) - @author

### Bug Fixes
- Fix race condition in session handler (#125) - @author

### Performance
- Optimize database query for user lookup (#126) - @author

### Contributors
@author1, @author2, @author3

Options

Slack Format

When --format=slack or user asks for Slack-friendly output:

*Release v1.3.0* (2025-02-05)

*Breaking Changes*
- Description of breaking change (<link|#PR>)

*Features*
- Add user authentication flow (<link|#123>)

*Bug Fixes*
- Fix race condition in session handler (<link|#125>)

JSON Format

{
  "version": "v1.3.0",
  "date": "2025-02-05",
  "range": "v1.2.0..v1.3.0",
  "categories": {
    "breaking": [],
    "features": [],
    "fixes": [],
    "performance": [],
    "other": []
  },
  "contributors": [],
  "stats": {
    "total_commits": 42,
    "files_changed": 87,
    "insertions": 1234,
    "deletions": 567
  }
}

Edge Cases

• No tags exist: Use commit count or date range, warn user
• Non-conventional commits: Best-effort categorization from message content
• Monorepo: If user specifies a path, scope with git log -- path/
• Squash merges: Parse PR title from squash commit message
• Co-authored commits: Extract Co-authored-by trailers