update-changelog.yml

name: Update CHANGELOG.md

# Prepend the GitHub Release body to CHANGELOG.md when a release is
# published. Released-bearing repos (npm/PyPI/marketplace/GHCR) all use
# softprops/action-gh-release with `generate_release_notes: true` in their
# CD workflow, which means GitHub's auto-generated notes (PR titles since
# the previous tag) are the authoritative changelog. This workflow simply
# mirrors that into a checked-in CHANGELOG.md so people who don't browse
# Releases still see the history.

on:
  release:
    types: [published]

permissions:
  contents: write

jobs:
  update:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
        with:
          ref: main
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Prepend release entry to CHANGELOG.md
        env:
          TAG: ${{ github.event.release.tag_name }}
          NAME: ${{ github.event.release.name }}
          BODY: ${{ github.event.release.body }}
          DATE: ${{ github.event.release.published_at }}
        run: |
          set -euo pipefail
          [ -f CHANGELOG.md ] || { echo "::warning::CHANGELOG.md missing — skipping"; exit 0; }
          DAY="${DATE:0:10}"
          HEADER="## [${NAME:-$TAG}] - $DAY"

          # Write the body to a tmp file so we don't have to inline-escape it.
          printf '%s\n' "$BODY" > /tmp/release-body

          if grep -q '^## \[Unreleased\]' CHANGELOG.md; then
            # Insert after the "## [Unreleased]" line + its blank line, so the
            # Unreleased section stays at the top and manual in-flight notes
            # are preserved.
            awk -v hdr="$HEADER" -v body_file="/tmp/release-body" '
              BEGIN { inserted = 0 }
              {
                print
                if (!inserted && /^## \[Unreleased\]/) {
                  getline blank
                  print blank
                  print hdr
                  print ""
                  while ((getline line < body_file) > 0) print line
                  close(body_file)
                  print ""
                  inserted = 1
                }
              }
            ' CHANGELOG.md > CHANGELOG.md.new
          else
            { echo "$HEADER"; echo; cat /tmp/release-body; echo; cat CHANGELOG.md; } > CHANGELOG.md.new
          fi
          mv CHANGELOG.md.new CHANGELOG.md

      - name: Commit and push
        env:
          TAG: ${{ github.event.release.tag_name }}
        run: |
          if git diff --quiet -- CHANGELOG.md; then
            echo "No changes to CHANGELOG.md — release body was empty?"
            exit 0
          fi
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git add CHANGELOG.md
          git commit -m "docs(changelog): record $TAG [skip ci]"
          git push