fix(websocket): keep upgraded WebSocket tunnels on dedicated lifecycle timeouts

test/test.websocket-e2e.ts

@@ -415,4 +415,68 @@ tap.test('should handle large WebSocket messages', async () => {
   await assertPortsFree([PROXY_PORT, BACKEND_PORT]);
 });
 
+// ─── Test 7: Idle WebSocket outlives short HTTP socket timeout ───
+tap.test('should keep idle WebSocket open beyond HTTP socket timeout', async (tools) => {
+  tools.timeout(15000);
+
+  const [PROXY_PORT, BACKEND_PORT] = await findFreePorts(2);
+  let proxy: SmartProxy | undefined;
+  let ws: WebSocket | undefined;
+
+  const backendServer = http.createServer();
+  const wss = new WebSocketServer({ server: backendServer });
+
+  wss.on('connection', (backendWs) => {
+    backendWs.on('message', (data) => {
+      backendWs.send(`echo: ${data.toString()}`);
+    });
+  });
+
+  try {
+    await new Promise<void>((resolve) => {
+      backendServer.listen(BACKEND_PORT, '127.0.0.1', () => resolve());
+    });
+
+    proxy = new SmartProxy({
+      socketTimeout: 1000,
+      maxConnectionLifetime: 1000,
+      routes: [{
+        name: 'ws-idle-timeout-route',
+        match: { ports: PROXY_PORT },
+        action: {
+          type: 'forward',
+          targets: [{ host: '127.0.0.1', port: BACKEND_PORT }],
+          websocket: { enabled: true },
+        },
+      }],
+    });
+    await proxy.start();
+
+    const connection = connectWs(
+      `ws://127.0.0.1:${PROXY_PORT}/`,
+      { Host: 'test.local' },
+    );
+    ws = connection.ws;
+    await connection.opened;
+
+    await new Promise((resolve) => setTimeout(resolve, 6500));
+    expect(ws.readyState).toEqual(WebSocket.OPEN);
+
+    ws.send('still open');
+    await waitFor(() => connection.messages.length >= 1);
+    expect(connection.messages[0]).toEqual('echo: still open');
+  } finally {
+    if (ws && ws.readyState !== WebSocket.CLOSED) {
+      await closeWs(ws);
+    }
+    if (proxy) {
+      await proxy.stop();
+    }
+    wss.close();
+    await new Promise<void>((resolve) => backendServer.close(() => resolve()));
+    await new Promise((r) => setTimeout(r, 500));
+    await assertPortsFree([PROXY_PORT, BACKEND_PORT]);
+  }
+});
+
 export default tap.start();