changelog

name

changelog

description

Generates and updates CHANGELOG.md files by analyzing git commit history. Handles both creating new changelogs and appending recent changes. Analyzes commits using conventional commit format and categorizes changes. Use this skill when generating a new CHANGELOG.md file, updating CHANGELOG.md with recent changes, preparing for a release, documenting changes between versions, or when user mentions "update changelog", "generate changelog", "changelog", "release notes".

Changelog Management

Generates and updates CHANGELOG.md by analyzing git commit history with support for conventional commits and semantic versioning. Works with both new and existing changelog files.

Usage Scenarios

This skill supports two distinct workflows:

Scenario A: Preparing a Release

When: You are ready to create a new version release (e.g., v2.1.0)

Process:

1. Analyze commits since last release
2. Review and edit generated entries
3. Use update_changelog.py to automatically insert a new version section
4. Commit and tag the release

Result: CHANGELOG.md gets a new version section like ## [2.1.0] - 2025-11-25

Scenario B: Daily Development (No Release Yet)

When: You want to document recent changes but are not ready to release

Process:

1. Analyze recent commits
2. Review and edit generated entries
3. Manually update the [Unreleased] section in CHANGELOG.md
4. Do NOT use update_changelog.py (that's only for releases)

Result: CHANGELOG.md's [Unreleased] section gets updated with new changes

Important: For daily development, always edit CHANGELOG.md manually to add entries under [Unreleased]. The update_changelog.py script is only for creating formal release versions.

Quick Start

Generate changelog for commits since last tag:

python scripts/analyze_commits.py --since-last-tag > new_entries.md

Or specify a commit range:

python scripts/analyze_commits.py --from=v1.0.0 --to=HEAD

Workflow

Copy this checklist and track your progress:

Changelog Generation:
- [ ] Step 1: Identify version range
- [ ] Step 2: Analyze commits
- [ ] Step 3: Review and categorize
- [ ] Step 4: Update CHANGELOG.md
- [ ] Step 5: Verify formatting

Step 1: Identify version range

Determine which commits to include:

For new release: Use commits since last tag

git describe --tags --abbrev=0  # Get last tag

For specific range: Specify commit range

git log --oneline <from-ref>..<to-ref>

Step 2: Analyze commits

Run the analysis script:

python scripts/analyze_commits.py --since-last-tag --format=markdown

This outputs categorized changes by type:

• Features (feat:)
• Bug Fixes (fix:)
• Documentation (docs:)
• Refactoring (refactor:)
• Performance (perf:)
• Tests (test:)
• Build/Chores (build:, chore:, ci:)
• Styles (style:)

Step 3: Review and categorize

Review the generated output:

• Verify commit categorization is correct
• Edit descriptions for clarity
• Combine related changes if needed
• Remove internal/non-user-facing changes

Step 4: Update CHANGELOG.md

First time setup: If CHANGELOG.md doesn't exist, create it from template:

cp templates/changelog_template.md CHANGELOG.md

Choose your approach based on scenario:

For Release (Scenario A): Use update_changelog.py

When preparing a formal release, use the automation script:

# Save generated entries to a file
python scripts/analyze_commits.py --since-last-tag > /tmp/new_entries.md

# Review and edit /tmp/new_entries.md as needed

# Use script to insert new version section
python scripts/update_changelog.py 2.1.0 /tmp/new_entries.md

The script automatically:

• Inserts new version section with date
• Places it after [Unreleased] or before first version
• Updates comparison links (if --repo-url provided)

Format (automatically created by script):

## [2.1.0] - 2025-11-25

### Added
- New feature descriptions

### Fixed
- Bug fix descriptions

For Daily Development (Scenario B): Manual Edit

When documenting changes without releasing, manually edit CHANGELOG.md:

1. Open CHANGELOG.md in your editor
2. Locate the [Unreleased] section
3. Add the generated entries under appropriate subsections
4. Keep existing unreleased entries if any

Format (manual editing):

## [Unreleased]

### Added
- New feature from today's commits
- Previous unreleased feature (keep this)

### Fixed
- Bug fix from today's commits

Important: Do NOT use update_changelog.py for daily development. That script is ONLY for creating versioned releases.

Step 5: Verify formatting

Check the updated CHANGELOG.md:

• Date format is YYYY-MM-DD
• Sections are in standard order
• Links work (if using reference-style)
• Formatting is consistent

Commit Message Conventions

This skill expects Conventional Commits format:

<type>(<scope>): <description>

[optional body]

[optional footer]

Recognized types:

• feat: New feature
• fix: Bug fix
• docs: Documentation changes
• style: Code style changes (formatting, etc.)
• refactor: Code refactoring
• perf: Performance improvements
• test: Test additions or changes
• build: Build system changes
• ci: CI/CD changes
• chore: Other changes (maintenance, etc.)

Breaking changes: Include BREAKING CHANGE: in commit footer or append an exclamation mark after the type (e.g., feat!:)

Customization

Filtering commits

Exclude certain commit types:

python scripts/analyze_commits.py --exclude-types=chore,style

Custom categories

Edit scripts/analyze_commits.py to modify the COMMIT_CATEGORIES mapping.

Include emojis

Many projects use emojis in commits. The script preserves them by default.

To strip emojis from changelog:

python scripts/analyze_commits.py --strip-emojis

Output Formats

Markdown (default):

python scripts/analyze_commits.py --format=markdown

JSON (for programmatic use):

python scripts/analyze_commits.py --format=json

Scripts Reference

analyze_commits.py

Analyzes git commits and generates categorized changelog entries.

Usage:

python scripts/analyze_commits.py [OPTIONS]

Required Options (one of):

• --since-last-tag: Analyze commits since the most recent git tag
• --from=<ref>: Starting commit/tag reference (e.g., v1.0.0, abc123)

Optional Arguments:

• --to=<ref>: Ending commit/tag reference (default: HEAD)
• --exclude-types=<types>: Comma-separated list of commit types to exclude
  • Example: --exclude-types=chore,style
• --format=<format>: Output format, either markdown or json (default: markdown)
• --strip-emojis: Remove emoji characters from commit descriptions
• --include-hashes: Include short commit hashes (7 chars) in output

Examples:

# Analyze all commits since last tag
python scripts/analyze_commits.py --since-last-tag

# Analyze specific range
python scripts/analyze_commits.py --from=v1.0.0 --to=v2.0.0

# Exclude maintenance commits
python scripts/analyze_commits.py --since-last-tag --exclude-types=chore,style,test

# Include commit hashes for reference
python scripts/analyze_commits.py --from=v1.0.0 --include-hashes

# Clean output without emojis
python scripts/analyze_commits.py --since-last-tag --strip-emojis

# JSON output for automation
python scripts/analyze_commits.py --since-last-tag --format=json

Output Format (Markdown):

### Added
- feature description
- another feature

### Fixed
- bug fix description

Output Format (JSON):

{
  "Added": [
    {"description": "feature description", "hash": "abc1234", "breaking": false}
  ],
  "Fixed": [
    {"description": "bug fix description", "hash": "def5678", "breaking": false}
  ]
}

update_changelog.py

Updates CHANGELOG.md file with a new version section.

IMPORTANT - When to use this script:

• ✅ USE: When preparing a formal release (Scenario A)
• ❌ DO NOT USE: For daily development without release (Scenario B)
• For daily development, manually edit the [Unreleased] section instead

Usage:

python scripts/update_changelog.py <version> <entries_file> [OPTIONS]

Required Arguments:

• version: Version number in semver format (e.g., 1.2.0, 2.0.0-beta.1)
• entries_file: Path to file containing markdown-formatted changelog entries

Optional Arguments:

• --changelog=<path>: Path to CHANGELOG.md file (default: CHANGELOG.md)
• --date=<date>: Release date in YYYY-MM-DD format (default: today's date)
• --repo-url=<url>: Repository URL for generating version comparison links

Examples:

# Basic usage with today's date
python scripts/update_changelog.py 2.1.0 /tmp/new_entries.md

# Specify custom date
python scripts/update_changelog.py 2.1.0 /tmp/new_entries.md --date=2025-11-25

# Include repository links
python scripts/update_changelog.py 2.1.0 /tmp/new_entries.md \
  --repo-url=https://github.com/user/repo

# Custom CHANGELOG location
python scripts/update_changelog.py 2.1.0 /tmp/new_entries.md \
  --changelog=docs/CHANGELOG.md

# Complete example with all options
python scripts/update_changelog.py 2.1.0 /tmp/new_entries.md \
  --changelog=CHANGELOG.md \
  --date=2025-11-25 \
  --repo-url=https://github.com/user/repo

Behavior:

• Inserts new version section after [Unreleased] section (if present)
• Or inserts before first existing version section
• Automatically updates comparison links if --repo-url provided
• Creates properly formatted version header with date

Example entries_file format:

### Added
- New feature for users
- Another cool feature

### Fixed
- Critical bug fix
- Minor UI issue

Example Usage

Example 1: Preparing a Release (Scenario A)

You are ready to release v2.1.0 after accumulating several commits:

# Step 1: Analyze commits since last release
python scripts/analyze_commits.py --since-last-tag > /tmp/v2.1.0_entries.md

# Step 2: Review and edit /tmp/v2.1.0_entries.md
# - Fix typos, improve descriptions
# - Remove internal-only changes
# - Combine related commits

# Step 3: Use script to update CHANGELOG.md
python scripts/update_changelog.py 2.1.0 /tmp/v2.1.0_entries.md \
  --repo-url=https://github.com/user/repo

# Step 4: Review CHANGELOG.md to verify insertion

# Step 5: Commit the changelog
git add CHANGELOG.md
git commit -m "docs: update CHANGELOG for v2.1.0"

# Step 6: Create release tag
git tag -a v2.1.0 -m "Release v2.1.0"
git push origin v2.1.0

Result: CHANGELOG.md now has a new ## [2.1.0] - 2025-11-25 section.

Example 2: Daily Development (Scenario B)

You made some commits today and want to document them, but not ready to release:

# Step 1: Analyze recent commits (last 5 commits)
git log --oneline -5  # Check what commits to include
python scripts/analyze_commits.py --from=HEAD~5 --to=HEAD > /tmp/recent_changes.md

# Step 2: Review /tmp/recent_changes.md
# Edit for clarity and relevance

# Step 3: Manually open CHANGELOG.md and edit [Unreleased] section
# DO NOT use update_changelog.py

# Step 4: Copy relevant entries from /tmp/recent_changes.md
#         Paste under [Unreleased] section in CHANGELOG.md

# Step 5: Commit the updated changelog
git add CHANGELOG.md
git commit -m "docs: update unreleased changes in CHANGELOG"

Result: CHANGELOG.md's [Unreleased] section is updated with new entries.

Key difference: No version section created, no script used, manual editing only.

Templates

See templates/changelog_template.md for the standard CHANGELOG structure.

Tips

• Run analysis before creating tag: Easier to identify the commit range
• Keep entries user-focused: Rewrite technical commits for end-users
• Group related changes: Combine multiple commits about same feature
• Use imperative mood: "Add feature" not "Added feature"
• Link to issues/PRs: Include references when relevant
• Mark breaking changes clearly: Use dedicated section or ⚠️ marker