generate-changelog

Automated Changelog Generation

Generates a production-ready changelog by aggregating merged PRs since the last release/tag. Auto-classifies entries by type (features, fixes, breaking changes, dependencies). Outputs markdown and optionally publishes to GitHub Release and Slack.

Usage

/generate-changelog [--from <tag>] [--to <ref>] [--github-release] [--slack] [--file <path>] [--format keep-a-changelog]

• --from <tag>: Start from git tag (defaults to last tag)
• --to <ref>: End at git ref (defaults to HEAD)
• --github-release: Create GitHub Release with changelog
• --slack: Post summary to Slack channel
• --file <path>: Append changelog to file (CHANGELOG.md by default)
• --format: Output format (keep-a-changelog, simple)

Workflow

Phase 1: Detect Version Range

Identifies commit range between last release and HEAD.

// Detect last git tag
let fromRef = null;
try {
  const tags = execSync("git tag --sort=-version:refname --list 'v*' | head -20")
    .toString()
    .trim()
    .split("\n")
    .filter(t => t);

  if (tags.length === 0) {
    fromRef = execSync("git rev-list --all | tail -1").toString().trim();
    console.log(`ℹ No tags found; scanning from first commit`);
  } else {
    fromRef = tags[0];
    console.log(`✓ Last release: ${fromRef}`);
  }
} catch (err) {
  console.error(`ERROR: Failed to detect git tags: ${err.message}`);
  return gracefulFailure("Unable to detect version range; specify --from manually");
}

const toRef = argv.to || "HEAD";

// Verify range is valid
try {
  const logOutput = execSync(`git log --oneline ${fromRef}..${toRef}`);
  const commitCount = logOutput.toString().split("\n").filter(l => l).length;
  console.log(`✓ Commit range: ${fromRef}..${toRef} (${commitCount} commits)`);
} catch (err) {
  console.error(`ERROR: Invalid git range ${fromRef}..${toRef}`);
  return gracefulFailure("Unable to determine changelog range");
}

Graceful degradation: If no tags, scan from first commit; allow manual range specification.