diff --git a/test/vitest-ui-e2e-preflight.test.ts b/test/vitest-ui-e2e-preflight.test.ts
index 7a8d72a3df48..cf7007e1c1fc 100644
--- a/test/vitest-ui-e2e-preflight.test.ts
+++ b/test/vitest-ui-e2e-preflight.test.ts
@@ -2,7 +2,11 @@ import { createServer } from "node:http";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { assertUiE2ePreflight } from "./vitest/vitest.ui-e2e-preflight.ts";
 
-vi.mock("node:http", { spy: true });
+vi.mock("node:http", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("node:http")>();
+  // Native HTTP and socket prototypes outlive a test file in shared workers.
+  return { ...actual, createServer: vi.fn(actual.createServer) };
+});
 
 const listeners: Array<{
   server: ReturnType<typeof createServer>;
@@ -22,14 +26,19 @@ beforeEach(async () => {
 });
 
 afterEach(async () => {
-  // Keep a failed cleanup assertion from leaking its real listener into later tests.
-  for (const { server } of listeners) {
-    server.closeAllConnections();
-    if (server.listening) {
-      await new Promise<void>((resolve, reject) => {
-        server.close((error) => (error ? reject(error) : resolve()));
-      });
+  try {
+    // Keep a failed cleanup assertion from leaking its real listener into later tests.
+    for (const { server } of listeners) {
+      server.closeAllConnections();
+      if (server.listening) {
+        await new Promise<void>((resolve, reject) => {
+          server.close((error) => (error ? reject(error) : resolve()));
+        });
+      }
     }
+  } finally {
+    // restoreAllMocks does not reset module spies' custom implementations.
+    vi.mocked(createServer).mockRestore();
   }
 });
 
@@ -43,6 +52,35 @@ function expectListenerClosed() {
 }
 
 describe("UI E2E environment preflight", () => {
+  it("preserves native HTTP and socket implementations for later shared-worker consumers", () => {
+    const nativeHttp = process.getBuiltinModule("node:http");
+    const nativeNet = process.getBuiltinModule("node:net");
+    for (const implementation of [
+      nativeHttp.Server,
+      nativeHttp.Agent,
+      nativeHttp.IncomingMessage,
+      nativeHttp.OutgoingMessage,
+      nativeHttp.ServerResponse,
+      nativeHttp.ClientRequest,
+      nativeHttp.createServer,
+      nativeNet.Socket,
+    ]) {
+      expect(vi.isMockFunction(implementation)).toBe(false);
+    }
+    for (const [prototype, method] of [
+      [nativeHttp.IncomingMessage.prototype, "read"],
+      [nativeHttp.OutgoingMessage.prototype, "write"],
+      [nativeHttp.OutgoingMessage.prototype, "end"],
+      [nativeHttp.globalAgent, "createConnection"],
+      [nativeNet.Socket.prototype, "write"],
+    ] as const) {
+      expect(prototype).toHaveProperty(
+        method,
+        expect.toSatisfy((implementation) => !vi.isMockFunction(implementation)),
+      );
+    }
+  });
+
   it("proves the owned HTTP response and releases its listener", async () => {
     const fetchImpl = vi.fn<typeof fetch>(fetch);
     await assertUiE2ePreflight({ fetchImpl });