diff --git a/scripts/e2e-static-server.mjs b/scripts/e2e-static-server.mjs
index 6ea4365..45fb0b3 100644
--- a/scripts/e2e-static-server.mjs
+++ b/scripts/e2e-static-server.mjs
@@ -80,6 +80,11 @@ server.on('upgrade', (req, socket, head) => {
     socket.destroy();
     return;
   }
+  // A WebSocket that is dropped abruptly (e.g. a test toggling the browser
+  // offline, or a context closing) emits 'error' on these sockets. Without a
+  // listener that becomes an uncaught exception that would crash this server —
+  // so always handle it and just tear the pair down.
+  socket.on('error', () => socket.destroy());
   const upstream = httpRequest({
     hostname: COLLAB_TARGET.hostname,
     port: COLLAB_TARGET.port,
@@ -88,6 +93,7 @@ server.on('upgrade', (req, socket, head) => {
     headers: { ...req.headers, host: `${COLLAB_TARGET.hostname}:${COLLAB_TARGET.port}` },
   });
   upstream.on('upgrade', (upstreamRes, upstreamSocket, upstreamHead) => {
+    upstreamSocket.on('error', () => socket.destroy());
     const statusLine = `HTTP/1.1 ${upstreamRes.statusCode} ${upstreamRes.statusMessage}\r\n`;
     const headerLines = Object.entries(upstreamRes.headers)
       .map(([key, value]) => `${key}: ${value}`)
@@ -96,13 +102,18 @@ server.on('upgrade', (req, socket, head) => {
     if (upstreamHead?.length) socket.write(upstreamHead);
     upstreamSocket.pipe(socket);
     socket.pipe(upstreamSocket);
-    upstreamSocket.on('error', () => socket.destroy());
   });
   upstream.on('error', () => socket.destroy());
   if (head?.length) upstream.write(head);
   upstream.end();
 });
 
+// Last-resort guard: this is a throwaway test server, so a stray socket error
+// must never take it down mid-run and fail an unrelated later test pack.
+process.on('uncaughtException', (error) => {
+  console.error('e2e static server: ignored uncaught error:', error?.message ?? error);
+});
+
 server.listen(PORT, () =>
   console.log(
     `e2e static server on :${PORT} → api ${API_TARGET.href} collab ${COLLAB_TARGET.href}`,