Fix flaky embed tests: identity loading outlives jsdom teardown

app/src/App.tsx

@@ -347,7 +347,12 @@ function App({ config: configOverrides }: { config?: Partial<WriteConfig> } = {}
     let active = true;
     let opened: LocalProject | null = null;
     void (async () => {
-      const loadedIdentity = await loadIdentity(config);
+      // Identity loading can't be cancelled, so ignore its result (or failure) after unmount.
+      const loadedIdentity = await loadIdentity(config).catch((error) => {
+        if (active) throw error;
+        return null;
+      });
+      if (!active || !loadedIdentity) return;
       const loadedProject = await LocalProject.open(
         loadedIdentity,
         config,

app/src/embed.test.ts

@@ -1,9 +1,34 @@
-import { afterEach, describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import { defineCustomElement, mount } from "./embed";
+import type { DeviceIdentity } from "./lib/identity";
+import { LocalProject } from "./lib/project";
+
+// Track every identity load App starts so each test can wait for them to settle;
+// otherwise they outlive the test and touch jsdom globals after teardown.
+const identityLoads = vi.hoisted(() => ({
+  pending: new Set<Promise<unknown>>(),
+  override: null as (() => Promise<DeviceIdentity>) | null,
+}));
+
+vi.mock("./lib/identity", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("./lib/identity")>();
+  return {
+    ...actual,
+    loadIdentity: (...args: Parameters<typeof actual.loadIdentity>) => {
+      const load = identityLoads.override?.() ?? actual.loadIdentity(...args);
+      identityLoads.pending.add(load);
+      return load;
+    },
+  };
+});
 
 const flush = () => new Promise((resolve) => setTimeout(resolve, 0));
 
-afterEach(() => {
+afterEach(async () => {
+  await Promise.allSettled(identityLoads.pending);
+  identityLoads.pending.clear();
+  identityLoads.override = null;
+  vi.restoreAllMocks();
   document.body.replaceChildren();
   document.getElementById("subscript-write-styles")?.remove();
 });
@@ -21,11 +46,12 @@ describe("embeddable library entry", () => {
 
     const otherHost = document.createElement("div");
     document.body.append(otherHost);
-    mount(otherHost);
+    const otherHandle = mount(otherHost);
     await flush();
     expect(document.querySelectorAll("#subscript-write-styles")).toHaveLength(1);
 
     handle.unmount();
+    otherHandle.unmount();
     expect(host.querySelector(".subscript-write")).toBeNull();
   });
 
@@ -40,4 +66,31 @@ describe("embeddable library entry", () => {
     element.remove();
     expect(element.querySelector(".subscript-write")).toBeNull();
   });
+
+  it("ignores identity loading that settles after unmount", async () => {
+    let failLoad: (error: Error) => void = () => undefined;
+    identityLoads.override = () =>
+      new Promise<DeviceIdentity>((_, reject) => {
+        failLoad = reject;
+      });
+    const open = vi.spyOn(LocalProject, "open");
+    const unhandled = vi.fn();
+    process.on("unhandledRejection", unhandled);
+
+    try {
+      const host = document.createElement("div");
+      document.body.append(host);
+      const handle = mount(host);
+      await flush();
+      handle.unmount();
+
+      failLoad(new ReferenceError("localStorage is not defined"));
+      await flush();
+
+      expect(open).not.toHaveBeenCalled();
+      expect(unhandled).not.toHaveBeenCalled();
+    } finally {
+      process.off("unhandledRejection", unhandled);
+    }
+  });
 });