diff --git a/packages/utils/network.ts b/packages/utils/network.ts
index 3b3790754c0ba..edc54285a0746 100644
--- a/packages/utils/network.ts
+++ b/packages/utils/network.ts
@@ -228,6 +228,11 @@ async function httpStatusCode(url: URL, ignoreHTTPSErrors: boolean, onLog?: (dat
 }
 
 export function decorateServer(server: net.Server) {
+  // Windows named-pipe servers pre-post only 4 accept instances by default,
+  // so concurrent clients can transiently fail to connect. Node reads this
+  // env var when a server starts listening on a pipe.
+  if (process.platform === 'win32')
+    process.env.NODE_PENDING_PIPE_INSTANCES ??= '32';
   const sockets = new Set<net.Socket>();
   server.on('connection', socket => {
     sockets.add(socket);
diff --git a/tests/mcp/annotate.spec.ts b/tests/mcp/annotate.spec.ts
index ded999196d90f..8ae2873759626 100644
--- a/tests/mcp/annotate.spec.ts
+++ b/tests/mcp/annotate.spec.ts
@@ -455,7 +455,7 @@ test('should switch screencast to -s session on show --annotate', async ({ conne
   await cli('-s=first', 'show', { bindTitle });
   const browser = await connectToDashboard(bindTitle);
   const dashboard = browser.contexts()[0].pages()[0];
-  await expect(dashboard.locator('#display')).toBeVisible();
+  await expect(dashboard.locator('#display')).toBeVisible({ timeout: 15_000 });
 
   const sampleCenter = () => dashboard.evaluate(() => {
     const img = document.querySelector('#display') as HTMLImageElement | null;
@@ -480,7 +480,7 @@ test('should switch screencast to -s session on show --annotate', async ({ conne
   void annotatePromise.finally(() => { done = true; });
 
   await expect(dashboard.getByRole('main', { name: 'Dashboard: annotate' })).toBeVisible({ timeout: 15_000 });
-  await expect(activeSession(dashboard)).toHaveAccessibleName('Session second');
+  await expect(activeSession(dashboard)).toHaveAccessibleName('Session second', { timeout: 15_000 });
 
   await expect.poll(async () => {
     const c = await sampleCenter();