release-notes.yml

name: Auto Release Notes

on:
  release:
    types: [created, edited]

jobs:
  notes:
    runs-on: ubuntu-latest
    permissions:
      contents: write
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Generate release notes if body is empty or minimal
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          TAG: ${{ github.event.release.tag_name }}
          RELEASE_ID: ${{ github.event.release.id }}
        run: |
          BODY=$(gh release view "$TAG" --json body -q .body)

          # Skip if body has idempotency marker (already auto-generated)
          if echo "$BODY" | grep -q '<!-- auto-generated -->'; then
            echo "Release notes already auto-generated, skipping."
            exit 0
          fi

          # Skip if body has meaningful content (> 50 chars)
          if [ ${#BODY} -gt 50 ]; then
            echo "Release body has ${#BODY} chars (> 50), skipping."
            exit 0
          fi

          # Detect previous tag for accurate changelog diff
          PREV_TAG=$(git tag --sort=-v:refname | grep -A1 "^${TAG}$" | tail -1)
          if [ -z "$PREV_TAG" ] || [ "$PREV_TAG" = "$TAG" ]; then
            PREV_TAG=""
          fi

          # Generate notes via GitHub API
          if [ -n "$PREV_TAG" ]; then
            NOTES=$(gh api "repos/${{ github.repository }}/releases/generate-notes" \
              -f tag_name="$TAG" \
              -f previous_tag_name="$PREV_TAG" \
              --jq '.body' 2>/dev/null || echo "")
          else
            NOTES=$(gh api "repos/${{ github.repository }}/releases/generate-notes" \
              -f tag_name="$TAG" \
              --jq '.body' 2>/dev/null || echo "")
          fi

          # Fallback: use --generate-notes flag if API call failed
          if [ -z "$NOTES" ]; then
            gh release edit "$TAG" --generate-notes
            echo "Used gh release edit --generate-notes fallback."
            exit 0
          fi

          # Append idempotency marker and update release
          MARKER="<!-- auto-generated -->"
          NOTES=$(printf '%s\n\n%s' "$NOTES" "$MARKER")
          gh api "repos/${{ github.repository }}/releases/${RELEASE_ID}" \
            -X PATCH -f body="$NOTES"
          echo "Release notes generated for $TAG (previous: ${PREV_TAG:-none})."