Tolerate previews of Workers that cannot have preview URLs

.github/workflows/cloudflare-pr.yml

@@ -83,6 +83,7 @@ jobs:
       - uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
         env:
           PREVIEW_URL: ${{ needs.preview-candidate.outputs.deployment-url }}
+          PREVIEW_NOTE: ${{ needs.preview-candidate.outputs.preview-note }}
           RELEASE_PREFIX: ${{ fromJSON(needs.quality.outputs.deployment-policy).releasePrefix }}
           VERSION_ID: ${{ needs.preview-candidate.outputs.version-id }}
         with:
@@ -96,6 +97,7 @@ jobs:
               marker,
               `### ${heading}`,
               `- Preview: ${process.env.PREVIEW_URL}`,
+              ...(process.env.PREVIEW_NOTE ? [`- Note: ${process.env.PREVIEW_NOTE}`] : []),
               `- Cloudflare version: \`${process.env.VERSION_ID}\``,
               `- Commit: \`${context.sha}\``,
             ].join('\n')

.github/workflows/cloudflare-version.yml

@@ -43,6 +43,10 @@ on:
         value: ${{ jobs.version.outputs.version-id }}
       deployment-url:
         value: ${{ jobs.version.outputs.deployment-url }}
+      # Non-empty only when a preview produced no preview URL (Durable Object
+      # Workers never get one) and deployment-url fell back to the target.
+      preview-note:
+        value: ${{ jobs.version.outputs.preview-note }}
 
 permissions:
   contents: read
@@ -60,6 +64,7 @@ jobs:
     outputs:
       version-id: ${{ steps.metadata.outputs.version-id }}
       deployment-url: ${{ steps.metadata.outputs.deployment-url }}
+      preview-note: ${{ steps.metadata.outputs.preview-note }}
     defaults:
       run:
         working-directory: ${{ fromJSON(inputs.quality-policy).workingDirectory }}
@@ -237,21 +242,38 @@ jobs:
         run: |
           VERSION_ID=$(printf '%s' "$COMMAND_OUTPUT" | grep -oE '(Worker )?Version ID: +[a-f0-9-]+' | head -1 | grep -oE '[a-f0-9-]{8,}' || true)
           PREVIEW_URL=$(printf '%s' "$COMMAND_OUTPUT" | grep -oE 'https://[^[:space:]]+\.workers\.dev[^[:space:]]*' | head -1 || true)
+          PREVIEW_NOTE=""
           if [ "$OPERATION" = "preview" ]; then
             DEPLOYMENT_URL="${PREVIEW_URL:-$ACTION_URL}"
+            if [ -z "$DEPLOYMENT_URL" ]; then
+              # Cloudflare does not issue preview URLs for Workers that
+              # implement a Durable Object, Containers included — the upload
+              # succeeded and the version exists at 0% traffic, there is just
+              # no URL that serves it. Fall back to the target URL so the
+              # GitHub Environment and the PR comment point somewhere real,
+              # and carry a note so nobody mistakes it for the preview.
+              DEPLOYMENT_URL="$TARGET_URL"
+              PREVIEW_NOTE="no preview URL: Cloudflare does not generate them for Durable Object Workers; the version is uploaded at 0% traffic and the URL above is the live target"
+            fi
           else
             DEPLOYMENT_URL="${TARGET_URL:-$ACTION_URL}"
           fi
           if [ -z "$VERSION_ID" ] || [ -z "$DEPLOYMENT_URL" ]; then
             echo "::error::Cloudflare output did not contain version metadata"
             exit 1
           fi
-          echo "version-id=$VERSION_ID" >> "$GITHUB_OUTPUT"
-          echo "deployment-url=$DEPLOYMENT_URL" >> "$GITHUB_OUTPUT"
+          {
+            echo "version-id=$VERSION_ID"
+            echo "deployment-url=$DEPLOYMENT_URL"
+            echo "preview-note=$PREVIEW_NOTE"
+          } >> "$GITHUB_OUTPUT"
           {
             echo "### Cloudflare ${{ inputs.target }} ${{ inputs.operation }}"
             echo "- Tag: \`${{ inputs.version-tag }}\`"
             echo "- Version: \`$VERSION_ID\`"
             echo "- URL: $DEPLOYMENT_URL"
+            if [ -n "$PREVIEW_NOTE" ]; then
+              echo "- Note: $PREVIEW_NOTE"
+            fi
             echo "- Source: ${{ inputs.version-message }}"
           } >> "$GITHUB_STEP_SUMMARY"

tests/workflows.test.mjs

@@ -289,6 +289,31 @@ test("Wrangler metadata arguments remain single tokens", () => {
   );
 });
 
+test("preview metadata tolerates Workers without preview URLs", () => {
+  // Cloudflare never generates preview URLs for Workers that implement a
+  // Durable Object (Containers included) — `versions upload` succeeds with a
+  // Version ID and no URL. The metadata step must fall back to the target URL
+  // with an explanatory note instead of failing the preview, and the note must
+  // travel to the caller so cloudflare-pr.yml can surface it in the comment.
+  const source = fs.readFileSync(`${directory}/cloudflare-version.yml`, "utf8");
+  const workflow = parse(source);
+  const metadata = workflow.jobs.version.steps.find(
+    (step) => step.id === "metadata",
+  );
+  assert.match(metadata.run, /DEPLOYMENT_URL="\$TARGET_URL"/);
+  assert.match(metadata.run, /PREVIEW_NOTE=/);
+  assert.match(metadata.run, /Durable Object/);
+  assert.equal(
+    workflow.on.workflow_call.outputs["preview-note"].value,
+    "${{ jobs.version.outputs.preview-note }}",
+  );
+  const pr = parse(fs.readFileSync(`${directory}/cloudflare-pr.yml`, "utf8"));
+  const comment = pr.jobs["publish-preview"].steps.find(
+    (step) => step.env && step.env.PREVIEW_NOTE !== undefined,
+  );
+  assert.ok(comment, "PR comment step must receive the preview note");
+});
+
 test("Worker secrets are allowlisted, never forwarded wholesale", () => {
   // toJSON(secrets) in the publish step contains every secret the caller
   // inherited, the Cloudflare API token included. The allowlist is the entire