diff --git a/lib/desktop/__tests__/os-signout.test.ts b/lib/desktop/__tests__/os-signout.test.ts
new file mode 100644
index 000000000..d640b50b7
--- /dev/null
+++ b/lib/desktop/__tests__/os-signout.test.ts
@@ -0,0 +1,24 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+/** A sign-out leaves nothing of the account on the OS's surfaces. */
+
+vi.setConfig({ testTimeout: 60_000 });
+
+describe('sign-out', () => {
+  afterEach(() => {
+    window.bulwarkDesktop = undefined;
+  });
+
+  it('clears what the desktop app shows outside its windows', async () => {
+    const clearSurfaces = vi.fn();
+    window.bulwarkDesktop = { version: 1, platform: 'win32', os: { clearSurfaces } } as never;
+    const { purgeSignedOutData } = await import('@/lib/sign-out-cleanup');
+    purgeSignedOutData();
+    expect(clearSurfaces).toHaveBeenCalled();
+  });
+
+  it('in a browser there is nothing to clear', async () => {
+    const { clearDesktopSurfaces } = await import('../bridge');
+    expect(() => clearDesktopSurfaces()).not.toThrow();
+  });
+});