Add a new workflow to deploy page preview for PRs from forks

.github/workflows/cloudflare-preview.yml

@@ -0,0 +1,79 @@
+name: Cloudflare Pages Preview Deployment
+
+on:
+  # Runs automatically for PRs from ruby/rdoc
+  # Fork PRs will be filtered out by the if condition
+  pull_request:
+
+  # Allows manual triggering for fork PRs
+  workflow_dispatch:
+    inputs:
+      pull_request_number:
+        description: 'Pull Request Number (for fork PRs)'
+        required: true
+        type: string
+
+jobs:
+  deploy-preview:
+    runs-on: ubuntu-latest
+    # Skip if PR from fork and NOT manually triggered
+    if: ${{ github.event_name == 'workflow_dispatch' || github.event.pull_request.head.repo.full_name == 'ruby/rdoc' }}
+
+    steps:
+      - name: Checkout for PR from main repo
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+
+      - name: Checkout for manually triggered fork PR
+        if: ${{ github.event_name == 'workflow_dispatch' }}
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+
+      - name: Setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.4'
+          bundler-cache: true
+
+      - name: Install dependencies
+        run: bundle install
+
+      - name: Build site
+        run: bundle exec rake build
+
+      - name: Set PR Number
+        id: pr_number
+        run: |
+          if [ "${{ github.event_name }}" == "pull_request" ]; then
+            echo "PR_NUMBER=${{ github.event.pull_request.number }}" >> $GITHUB_ENV
+          else
+            echo "PR_NUMBER=${{ inputs.pull_request_number }}" >> $GITHUB_ENV
+          fi
+
+      # Deploy to Cloudflare Pages using wrangler-action
+      - name: Deploy to Cloudflare Pages
+        id: deploy
+        uses: cloudflare/wrangler-action@v3
+        with:
+          apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}
+          accountId: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
+          command: pages deploy ./_site --project-name=rdoc --branch="${{ env.PR_NUMBER }}-preview"
+
+      # Comment on PR with preview URL - works for both regular PRs and fork PRs
+      - name: Comment on PR with preview URL
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const prNumber = ${{ env.PR_NUMBER }};
+            const url = "${{ steps.deploy.outputs.deployment-url }}";
+
+            await github.rest.issues.createComment({
+              issue_number: prNumber,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `🚀 Preview deployment available at: [${url}](${url})`
+            });

.github/workflows/pr-preview-comment.yml

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+name: Comment on Fork PRs
+
+on:
+  pull_request:
+    types: [opened, reopened, synchronize]
+
+jobs:
+  comment-on-fork-pr:
+    runs-on: ubuntu-latest
+    # Only run for fork PRs
+    if: github.event.pull_request.head.repo.fork == true
+    steps:
+      - name: Comment on PR with manual deployment instructions
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const prNumber = context.payload.pull_request.number;
+            const workflowUrl = `https://github.com/ruby/rdoc/actions/workflows/cloudflare-preview.yml`;
+            const branch = context.payload.pull_request.head.ref;
+
+            // Create a direct link that pre-fills the PR number input
+            const dispatchUrl = `${workflowUrl}/dispatch?ref=main&inputs%5Bpull_request_number%5D=${prNumber}`;
+
+            await github.rest.issues.createComment({
+              issue_number: prNumber,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `## Cloudflare Preview Deployment
+
+                ⚠️ This PR is from a fork, so the preview deployment workflow doesn't run automatically for security reasons.
+
+                If you're a maintainer and want to preview this PR:
+
+                [➡️ Click here to run the workflow with PR #${prNumber} pre-filled](${dispatchUrl})
+
+                This will trigger a Cloudflare Pages preview deployment for this PR.`
+            });