release-notes.yml

name: Release notes preview

# On a promotion PR (alpha or beta into main or beta), keeps one comment with
# the version and release notes that adding the `promote` label would
# publish, made by the same code as the real ones. Fails a promotion into main
# that releases something without hand-written "## Release notes"; the
# promote bot waits for it. See release/preview.mjs.

on:
  pull_request:
    branches: [main, beta]
    types: [opened, edited, synchronize, reopened]

permissions: {}

jobs:
  preview:
    if: github.head_ref == 'alpha' || github.head_ref == 'beta'
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write
    steps:
      - uses: actions/checkout@v6
        with:
          fetch-depth: 0

      - name: Write the preview
        env:
          GITHUB_TOKEN: ${{ github.token }}
          BASE_REF: ${{ github.base_ref }}
          HEAD_REF: ${{ github.head_ref }}
          BASE_SHA: ${{ github.event.pull_request.base.sha }}
          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          PR_BODY: ${{ github.event.pull_request.body }}
        run: node release/preview.mjs >"$RUNNER_TEMP/preview.md"

      # Even when the step above failed for missing notes: the comment says
      # what to write. Not when it crashed and left nothing to post.
      - name: Post or update the comment
        if: always()
        env:
          GH_TOKEN: ${{ github.token }}
          PR: ${{ github.event.pull_request.number }}
        run: |
          [[ -s $RUNNER_TEMP/preview.md ]] || exit 0
          existing=$(gh api "repos/$GITHUB_REPOSITORY/issues/$PR/comments" --paginate \
            --jq '.[] | select(.body | startswith("<!-- release-notes-preview -->")) | .id' | head -1)
          if [[ -n $existing ]]; then
            gh api --method PATCH "repos/$GITHUB_REPOSITORY/issues/comments/$existing" \
              -F body=@"$RUNNER_TEMP/preview.md" >/dev/null
          else
            gh pr comment "$PR" --repo "$GITHUB_REPOSITORY" --body-file "$RUNNER_TEMP/preview.md"
          fi