Build an AI Changelog Generator from Git Commits

pip install anthropic

import subprocess
import anthropic
import sys

def get_commits(from_ref, to_ref="HEAD"):
    """Extract commits between two Git refs."""
    result = subprocess.run(
        ["git", "log", "--pretty=format:%h|%s|%an",
         f"{from_ref}..{to_ref}"],
        capture_output=True, text=True
    )
    commits = []
    for line in result.stdout.strip().split("\n"):
        if not line:
            continue
        hash, msg, author = line.split("|", 2)
        commits.append({"hash": hash, "message": msg, "author": author})
    return commits

def generate_changelog(commits, version):
    """Send commits to Claude and get a formatted changelog."""
    client = anthropic.Anthropic(
        base_url="https://ezaiapi.com"
    )

    commit_text = "\n".join(
        f"- {c['hash']}: {c['message']} ({c['author']})"
        for c in commits
    )

    message = client.messages.create(
        model="claude-sonnet-4-5",
        max_tokens=2048,
        messages=[{
            "role": "user",
            "content": f"""Generate a changelog for version {version}.

Raw commits:
{commit_text}

Rules:
1. Group into: 🚀 Features, 🐛 Bug Fixes, ⚡ Performance, 🔧 Internal, 💥 Breaking Changes
2. Rewrite each commit as a clear, user-facing description
3. Skip merge commits and CI-only changes
4. If a commit message is vague (e.g. "fix stuff"), infer from context
5. Output clean Markdown, no extra commentary"""
        }]
    )

    return message.content[0].text

# Usage
if __name__ == "__main__":
    from_tag = sys.argv[1]  # e.g., v1.2.0
    version = sys.argv[2]   # e.g., v1.3.0

    commits = get_commits(from_tag)
    if not commits:
        print("No commits found between refs.")
        sys.exit(1)

    print(f"Found {len(commits)} commits. Generating changelog...")
    changelog = generate_changelog(commits, version)
    print(changelog)

python changelog.py v1.2.0 v1.3.0

## v1.3.0

### 🚀 Features
- Added dark mode toggle with system preference detection
- New CSV export for analytics dashboard
- Webhook retry configuration (max attempts, backoff)

### 🐛 Bug Fixes
- Fixed pagination breaking on filtered views
- Resolved memory leak in WebSocket connection handler

### ⚡ Performance
- Database queries now use prepared statements (40% faster)
- Lazy-load images on the landing page

def get_commits_with_diff(from_ref, to_ref="HEAD"):
    """Extract commits with file-level diff stats."""
    result = subprocess.run(
        ["git", "log", "--pretty=format:COMMIT|%h|%s|%an",
         "--stat", f"{from_ref}..{to_ref}"],
        capture_output=True, text=True
    )

    commits = []
    current = None

    for line in result.stdout.split("\n"):
        if line.startswith("COMMIT|"):
            if current:
                commits.append(current)
            parts = line.split("|", 3)
            current = {
                "hash": parts[1],
                "message": parts[2],
                "author": parts[3],
                "files": []
            }
        elif current and "|" in line:
            # Parse stat lines like: src/auth.py | 15 +++---
            filename = line.split("|")[0].strip()
            if filename:
                current["files"].append(filename)

    if current:
        commits.append(current)
    return commits

name: Release with AI Changelog
on:
  push:
    tags:
      - 'v*'

jobs:
  release:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0  # Full history for git log

      - uses: actions/setup-python@v5
        with:
          python-version: '3.12'

      - run: pip install anthropic

      - name: Generate Changelog
        env:
          ANTHROPIC_API_KEY: ${{ secrets.EZAI_API_KEY }}
        run: |
          PREV_TAG=$(git describe --tags --abbrev=0 HEAD^)
          python changelog.py $PREV_TAG ${{ github.ref_name }} > RELEASE_NOTES.md

      - name: Create GitHub Release
        uses: softprops/action-gh-release@v2
        with:
          body_path: RELEASE_NOTES.md

def generate_changelog_batched(commits, version, batch_size=50):
    """Process large commit lists in batches."""
    client = anthropic.Anthropic(base_url="https://ezaiapi.com")
    partial_logs = []

    for i in range(0, len(commits), batch_size):
        batch = commits[i:i + batch_size]
        commit_text = "\n".join(
            f"- {c['hash']}: {c['message']}" for c in batch
        )
        resp = client.messages.create(
            model="claude-sonnet-4-5",
            max_tokens=1024,
            messages=[{"role": "user",
                       "content": f"Categorize these commits as changelog entries:\n{commit_text}"}]
        )
        partial_logs.append(resp.content[0].text)

    # Final merge pass
    combined = "\n\n".join(partial_logs)
    merge = client.messages.create(
        model="claude-sonnet-4-5",
        max_tokens=2048,
        messages=[{"role": "user",
                   "content": f"Merge these partial changelogs into one clean changelog for {version}. Deduplicate and group properly:\n\n{combined}"}]
    )
    return merge.content[0].text