Fix PR-preview deploys: write metadata after checkout (survives git clean)

.github/workflows/preview-deploy.yml

@@ -60,9 +60,15 @@ jobs:
 
       - name: Read PR metadata
         id: meta
+        # Fail loudly if the metadata is missing. A bare `$(cat missing)`
+        # inside `echo` yields empty output and exit 0, so the step would
+        # "pass" with empty pr-number/action and the deploy would silently
+        # skip (the regression this workflow pair just recovered from).
         run: |
-          echo "pr-number=$(cat _preview_download/meta/pr-number.txt)" >> "$GITHUB_OUTPUT"
-          echo "action=$(cat _preview_download/meta/action.txt)" >> "$GITHUB_OUTPUT"
+          pr_number=$(cat _preview_download/meta/pr-number.txt) || { echo "::error::Missing pr-number.txt in preview artifact"; exit 1; }
+          action=$(cat _preview_download/meta/action.txt) || { echo "::error::Missing action.txt in preview artifact"; exit 1; }
+          echo "pr-number=$pr_number" >> "$GITHUB_OUTPUT"
+          echo "action=$action" >> "$GITHUB_OUTPUT"
 
       - name: Deploy PR Preview
         if: steps.meta.outputs.action == 'deploy'

.github/workflows/preview.yml

@@ -42,18 +42,28 @@ jobs:
       contents: read
 
     steps:
-      - name: Save PR metadata
-        run: |
-          mkdir -p _preview_upload/meta
-          echo "${{ github.event.pull_request.number }}" > _preview_upload/meta/pr-number.txt
-          echo "${{ github.event.action == 'closed' && 'remove' || 'deploy' }}" > _preview_upload/meta/action.txt
-
       - name: Check out repository
         if: github.event.action != 'closed'
         uses: actions/checkout@v5
         with:
           submodules: recursive
 
+      # IMPORTANT: write the metadata AFTER checkout. actions/checkout runs
+      # `git clean -ffdx` (clean: true is the default), which deletes any
+      # untracked files already in the workspace — including a
+      # `_preview_upload/` directory created beforehand. With the metadata
+      # written before checkout, `_preview_upload/meta/` was wiped and never
+      # reached the artifact, so preview-deploy.yml read an empty pr-number,
+      # the deploy step's `action == 'deploy'` guard was false, and every
+      # deploy-path preview was silently skipped (the job still passed).
+      # For the 'closed'/remove event the checkout step is skipped, but this
+      # step is unguarded and still runs, so the remove path is unaffected.
+      - name: Save PR metadata
+        run: |
+          mkdir -p _preview_upload/meta
+          echo "${{ github.event.pull_request.number }}" > _preview_upload/meta/pr-number.txt
+          echo "${{ github.event.action == 'closed' && 'remove' || 'deploy' }}" > _preview_upload/meta/action.txt
+
       - name: Set up Quarto
         if: github.event.action != 'closed'
         uses: quarto-dev/quarto-actions/setup@v2