fix(play): tag runner postMessages with uuid for isolation

cloud-function/src/internal/play/index.js

@@ -444,16 +444,19 @@ export function renderHtml(state = null) {
           const consoleProxy = new Proxy(console, {
             get(target, prop) {
               if (typeof target[prop] === "function") {
+                const uuid =
+                  new URLSearchParams(location.search).get("uuid") || undefined;
                 return (...args) => {
                   try {
                     window.parent.postMessage(
-                      { typ: "console", prop, args },
+                      { uuid, typ: "console", prop, args },
                       "*"
                     );
                   } catch {
                     try {
                       window.parent.postMessage(
                         {
+                          uuid,
                           typ: "console",
                           prop,
                           args: args.map((x) => {
@@ -470,6 +473,7 @@ export function renderHtml(state = null) {
                     } catch {
                       window.parent.postMessage(
                         {
+                          uuid,
                           typ: "console",
                           prop: "warn",
                           args: [
@@ -537,7 +541,9 @@ export function renderHtml(state = null) {
         </script>
         <script>
           try {
-            window.parent.postMessage({ typ: "ready" }, "*");
+            const uuid =
+              new URLSearchParams(location.search).get("uuid") || undefined;
+            window.parent.postMessage({ uuid, typ: "ready" }, "*");
           } catch (e) {
             console.error("[Playground] Failed to post ready message", e);
           }

cloud-function/src/internal/play/index.test.js

@@ -0,0 +1,34 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+
+import { renderHtml } from "./index.js";
+
+describe("renderHtml", () => {
+  const output = renderHtml();
+
+  it("reads the uuid from the runner URL", () => {
+    assert.match(
+      output,
+      /new URLSearchParams\(location\.search\)\.get\("uuid"\) \|\| undefined/
+    );
+  });
+
+  const cases = [
+    { name: "ready", pattern: /postMessage\(\{ uuid, typ: "ready" \}, "\*"\)/ },
+    { name: "console", pattern: /\{ uuid, typ: "console", prop, args \}/ },
+    {
+      name: "console fallback",
+      pattern: /\{\s+uuid,\s+typ: "console",\s+prop,\s+args: args\.map/,
+    },
+    {
+      name: "console warn",
+      pattern: /\{\s+uuid,\s+typ: "console",\s+prop: "warn",/,
+    },
+  ];
+
+  for (const { name, pattern } of cases) {
+    it(`tags the ${name} message with the uuid`, () => {
+      assert.match(output, pattern);
+    });
+  }
+});