Preview changes

# Without --id (unique UUID each time)
[docs]: Published docs to https://fern-preview-c973a36e-337b-44f5-ab83-aab.docs.buildwithfern.com/learn
# With --id my-feature (stable URL)
[docs]: Published docs to https://fern-preview-my-feature.docs.buildwithfern.com/learn

name: Preview Docs
on:
  pull_request:
    types: [opened, synchronize, ready_for_review]
    branches:
      - main
jobs:
  run:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
      contents: read
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Setup Fern CLI
        uses: fern-api/setup-fern-cli@v1
      - name: Generate preview URL
        id: generate-docs
        env:
          FERN_TOKEN: ${{ secrets.FERN_TOKEN }}
          HEAD_REF: ${{ github.head_ref }}
        run: |
          OUTPUT=$(fern generate --docs --preview --id "$HEAD_REF" 2>&1) || true
          echo "$OUTPUT"
          URL=$(echo "$OUTPUT" | grep -oP 'Published docs to \K.*(?= \()')
          echo "preview_url=$URL" >> $GITHUB_OUTPUT
          echo "Preview URL: $URL"
      - name: Get page links for changed MDX files
        id: page-links
        env:
          FERN_TOKEN: ${{ secrets.FERN_TOKEN }}
        run: |
          PREVIEW_URL="${{ steps.generate-docs.outputs.preview_url }}"
          CHANGED_FILES=$(git diff --name-only origin/main...HEAD -- '*.mdx' 2>/dev/null || echo "")
          if [ -z "$CHANGED_FILES" ] || [ -z "$PREVIEW_URL" ]; then
            echo "page_links=" >> $GITHUB_OUTPUT; exit 0
          fi
          BASE_URL=$(echo "$PREVIEW_URL" | grep -oP 'https?://[^/]+')
          FILES_PARAM=$(echo "$CHANGED_FILES" | tr '\n' ',' | sed 's/,$//')
          RESPONSE=$(curl -sf -H "FERN_TOKEN: $FERN_TOKEN" "${PREVIEW_URL}/api/fern-docs/get-slug-for-file?files=${FILES_PARAM}" 2>/dev/null) || {
            echo "page_links=" >> $GITHUB_OUTPUT; exit 0
          }
          PAGE_LINKS=$(echo "$RESPONSE" | jq -r --arg url "$BASE_URL" \
            '.mappings[] | select(.slug != null) | "- [\(.slug)](\($url)/\(.slug))"')
          if [ -n "$PAGE_LINKS" ]; then
            { echo "page_links<<EOF"; echo "$PAGE_LINKS"; echo "EOF"; } >> $GITHUB_OUTPUT
          else
            echo "page_links=" >> $GITHUB_OUTPUT
          fi
      - name: Create comment content
        run: |
          echo ":herb: **Preview your docs:** <${{ steps.generate-docs.outputs.preview_url }}>" > comment.md
          if [ -n "${{ steps.page-links.outputs.page_links }}" ]; then
            echo "" >> comment.md
            echo "Here are the markdown pages you've updated:" >> comment.md
            echo "${{ steps.page-links.outputs.page_links }}" >> comment.md
          fi
      - name: Post PR comment
        uses: thollander/actions-comment-pull-request@v2.4.3
        with:
          filePath: comment.md
          comment_tag: preview-docs
          mode: upsert

name: Clean up preview links
on:
  pull_request:
    types: [closed]
jobs:
  cleanup:
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
      - name: Setup Fern CLI
        uses: fern-api/setup-fern-cli@v1
      - name: Delete preview deployment
        env:
          FERN_TOKEN: ${{ secrets.FERN_TOKEN }}
        run: |
          echo "Deleting preview for branch: ${{ github.head_ref }}"
          fern docs preview delete --id "${{ github.head_ref }}" || echo "Preview deletion returned non-zero — it may already be gone"