refactor(websocket): convert to pub/sub pattern with addListener/removeListener

Replace the single-listener createWebSocket pattern with a pub/sub model
using addListener/removeListener. This allows multiple components (header
spinner, dashboard refresh) to subscribe to WebSocket messages independently
without clobbering each other's handlers.

- Maintain a Set of message listeners
- Auto-connect on first addListener, auto-disconnect when last listener removed
- Retain reconnect logic with configurable delay

web/src/websocket.ts

@@ -1,84 +1,80 @@
 import { getToken } from "./storage";
-interface WebSocketConfig {
-  onMessage: (data: any) => void;
-  onOpen?: () => void;
-  onClose?: () => void;
-  onError?: (error: Event) => void;
-  enableReconnect?: boolean;
-  reconnectDelay?: number;
-}
+
+type MessageListener = (message: any) => void;
+
 let activeWebSocket: WebSocket | null = null;
 let reconnectTimeout: ReturnType<typeof setTimeout> | null = null;
-function createWebSocket(config: WebSocketConfig): WebSocket | null {
+let listeners: Set<MessageListener> = new Set();
+let currentConfig: { enableReconnect?: boolean; reconnectDelay?: number } = {};
+
+function connectWebSocket(): WebSocket | null {
   const token = getToken();
   if (!token) {
-    console.warn(
-      "No authentication token found - skipping WebSocket connection",
-    );
     return null;
   }
-  // Clean up existing connection
+
   if (activeWebSocket) {
-    activeWebSocket.close();
-  }
-  if (reconnectTimeout) {
-    clearTimeout(reconnectTimeout);
-    reconnectTimeout = null;
+    return activeWebSocket;
   }
+
   const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
   const wsUrl = `${protocol}//${window.location.host}/ws/sync?token=${token}`;
   const ws = new WebSocket(wsUrl);
+
   ws.onopen = () => {
     console.log("WebSocket connected");
-    if (config.onOpen) {
-      try {
-        config.onOpen();
-      } catch (error) {
-        console.error("Error in onOpen callback:", error);
-      }
-    }
   };
+
   ws.onmessage = (event: MessageEvent) => {
     try {
       const message = JSON.parse(event.data);
-      config.onMessage(message);
+      listeners.forEach((listener) => {
+        try {
+          listener(message);
+        } catch (error) {
+          console.error("Error in WebSocket listener:", error);
+        }
+      });
     } catch (error) {
       console.error("Error parsing WebSocket message:", error);
-      console.error("Raw message:", event.data);
     }
   };
+
   ws.onerror = (error: Event) => {
     console.error("WebSocket error:", error);
-    if (config.onError) {
-      try {
-        config.onError(error);
-      } catch (err) {
-        console.error("Error in onError callback:", err);
-      }
-    }
   };
+
   ws.onclose = () => {
     console.log("WebSocket disconnected");
+    activeWebSocket = null;
 
-    if (config.onClose) {
-      try {
-        config.onClose();
-      } catch (error) {
-        console.error("Error in onClose callback:", error);
-      }
-    }
-    // Auto-reconnect if enabled
-    if (config.enableReconnect !== false) {
-      const delay = config.reconnectDelay || 5000;
+    if (currentConfig.enableReconnect !== false) {
+      const delay = currentConfig.reconnectDelay || 5000;
       console.log(`Reconnecting in ${delay / 1000}s...`);
       reconnectTimeout = setTimeout(() => {
-        createWebSocket(config);
+        connectWebSocket();
       }, delay);
     }
   };
+
   activeWebSocket = ws;
   return ws;
 }
+
+function addListener(listener: MessageListener): void {
+  listeners.add(listener);
+  if (!activeWebSocket) {
+    connectWebSocket();
+  }
+}
+
+function removeListener(listener: MessageListener): void {
+  listeners.delete(listener);
+  if (listeners.size === 0) {
+    disconnectWebSocket();
+  }
+}
+
 function disconnectWebSocket(): void {
   if (reconnectTimeout) {
     clearTimeout(reconnectTimeout);
@@ -89,4 +85,44 @@ function disconnectWebSocket(): void {
     activeWebSocket = null;
   }
 }
-export { createWebSocket, disconnectWebSocket };
+
+function createWebSocket(config: {
+  onMessage: (data: any) => void;
+  onOpen?: () => void;
+  onClose?: () => void;
+  onError?: (error: Event) => void;
+  enableReconnect?: boolean;
+  reconnectDelay?: number;
+}): WebSocket | null {
+  currentConfig = config;
+
+  const listener: MessageListener = (message) => {
+    config.onMessage(message);
+  };
+
+  listeners.add(listener);
+
+  if (activeWebSocket) {
+    activeWebSocket.close();
+    activeWebSocket = null;
+  }
+
+  const ws = connectWebSocket();
+
+  if (ws && config.onOpen) {
+    if (ws.readyState === WebSocket.OPEN) {
+      config.onOpen();
+    } else {
+      ws.addEventListener("open", () => config.onOpen?.(), { once: true });
+    }
+  }
+
+  return ws;
+}
+
+export {
+  addListener,
+  createWebSocket,
+  disconnectWebSocket,
+  removeListener,
+};