fix: eliminate socket ghost connection and stale state on reconnect (#38)

- Reduce ping detection window from ~45s to ~15s (pingTimeout 5s, pingInterval 10s)
- Listen to window offline/online events for instant UI feedback on network drop
- Force immediate reconnect on online event instead of waiting for backoff
- Fix stuck-reconnecting bug when network returns within ping timeout window
- Wrap on/off/emit in useCallback to prevent listener re-registration every second
- Expose reconnectCount to trigger revalidator.revalidate() after each reconnect
- Reset hasConnectedOnce ref per socket instance to avoid spurious revalidations
- Remove stale socket ref from hook return value; add emit helper instead

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

app/hooks/useDraftSocket.ts

@@ -1,23 +1,29 @@
-import { useEffect, useRef, useState } from "react";
-import { io, Socket } from "socket.io-client";
+import { useCallback, useEffect, useRef, useState } from "react";
+import { io } from "socket.io-client";
 
 interface UseDraftSocketReturn {
-  socket: Socket | null;
   isConnected: boolean;
   connectionError: string | null;
   isReconnecting: boolean;
+  reconnectCount: number;
   on: (event: string, callback: (...args: any[]) => void) => void;
   off: (event: string, callback?: (...args: any[]) => void) => void;
+  emit: (event: string, ...args: any[]) => void;
 }
 
 export function useDraftSocket(seasonId: string, teamId?: string): UseDraftSocketReturn {
-  const socketRef = useRef<Socket | null>(null);
+  const socketRef = useRef<ReturnType<typeof io> | null>(null);
+  const hasConnectedOnce = useRef(false);
   const [isConnected, setIsConnected] = useState(false);
   const [connectionError, setConnectionError] = useState<string | null>(null);
   const [isReconnecting, setIsReconnecting] = useState(false);
+  const [reconnectCount, setReconnectCount] = useState(0);
 
   useEffect(() => {
-    // Connect to Socket.IO server
+    // Reset per-socket state so a new seasonId/teamId doesn't inherit the previous
+    // socket's connect history and falsely treat its first connect as a reconnect.
+    hasConnectedOnce.current = false;
+
     const socket = io({
       path: "/socket.io",
       transports: ["websocket", "polling"],
@@ -27,21 +33,23 @@ export function useDraftSocket(seasonId: string, teamId?: string): UseDraftSocke
 
     socket.on("connect", () => {
       console.log("Connected to Socket.IO:", socket.id);
+      const isReconnect = hasConnectedOnce.current;
+      hasConnectedOnce.current = true;
       setIsConnected(true);
       setConnectionError(null);
       setIsReconnecting(false);
-      // Join the draft room with optional teamId
       socket.emit("join-draft", seasonId, teamId);
+      if (isReconnect) {
+        setReconnectCount((c) => c + 1);
+      }
     });
 
     socket.on("disconnect", (reason) => {
       console.log("Disconnected from Socket.IO:", reason);
       setIsConnected(false);
       if (reason === "io server disconnect") {
-        // Server disconnected the socket, need to manually reconnect
         setConnectionError("Server disconnected. Please refresh the page.");
       } else {
-        // Client disconnected or network issue, will auto-reconnect
         setIsReconnecting(true);
       }
     });
@@ -64,32 +72,58 @@ export function useDraftSocket(seasonId: string, teamId?: string): UseDraftSocke
       setIsReconnecting(false);
     });
 
-    // Cleanup on unmount
+    const handleOffline = () => {
+      // Mark as reconnecting immediately — the OS fires this before Socket.IO's
+      // heartbeat would detect the drop (~15s later). Note: "offline" can fire
+      // spuriously on mobile; handleOnline corrects the state if the socket is
+      // still alive when the network returns.
+      setIsConnected(false);
+      setIsReconnecting(true);
+    };
+
+    const handleOnline = () => {
+      if (socketRef.current?.connected) {
+        // Network blipped but the socket stayed alive (came back within ping timeout window).
+        // The socket never disconnected so no "connect" event will fire — correct UI directly.
+        setIsConnected(true);
+        setIsReconnecting(false);
+      } else {
+        // Genuinely disconnected — skip backoff and reconnect immediately.
+        socketRef.current?.connect();
+      }
+    };
+
+    window.addEventListener("offline", handleOffline);
+    window.addEventListener("online", handleOnline);
+
     return () => {
-      if (socket) {
+      window.removeEventListener("offline", handleOffline);
+      window.removeEventListener("online", handleOnline);
       console.log("Leaving draft room:", seasonId);
       socket.emit("leave-draft", seasonId);
       socket.disconnect();
-      }
     };
   }, [seasonId, teamId]);
 
-  // Helper to subscribe to events
-  const on = (event: string, callback: (...args: any[]) => void) => {
+  const on = useCallback((event: string, callback: (...args: any[]) => void) => {
     socketRef.current?.on(event, callback);
-  };
+  }, []);
 
-  // Helper to unsubscribe from events
-  const off = (event: string, callback?: (...args: any[]) => void) => {
+  const off = useCallback((event: string, callback?: (...args: any[]) => void) => {
     socketRef.current?.off(event, callback);
-  };
+  }, []);
+
+  const emit = useCallback((event: string, ...args: any[]) => {
+    socketRef.current?.emit(event, ...args);
+  }, []);
 
   return {
-    socket: socketRef.current,
     isConnected,
     connectionError,
     isReconnecting,
+    reconnectCount,
     on,
-    off
+    off,
+    emit,
   };
 }

app/routes/leagues/$leagueId.draft.$seasonId.tsx

@@ -226,7 +226,7 @@ export default function DraftRoom() {
     ownerMap,
   } = useLoaderData<typeof loader>();
   const { revalidate } = useRevalidator();
-  const { isConnected, connectionError, isReconnecting, on, off } = useDraftSocket(season.id, userTeam?.id);
+  const { isConnected, connectionError, isReconnecting, reconnectCount, on, off } = useDraftSocket(season.id, userTeam?.id);
   const {
     permissionState: notificationsPermission,
     enabled: notificationsEnabled,
@@ -246,6 +246,14 @@ export default function DraftRoom() {
   useEffect(() => {
     notificationsModeRef.current = notificationsMode;
   }, [notificationsMode]);
+
+  // Re-fetch loader data after each reconnect so stale picks/timers are refreshed
+  useEffect(() => {
+    if (reconnectCount > 0) {
+      revalidate();
+    }
+  }, [reconnectCount, revalidate]);
+
   const [picks, setPicks] = useState(draftPicks);
   const [currentPick, setCurrentPick] = useState(season.currentPickNumber || 1);
   const [searchQuery, setSearchQuery] = useState("");
@@ -554,7 +562,11 @@ export default function DraftRoom() {
       off("pick-replaced", handlePickReplaced);
       off("draft-rolled-back", handleDraftRolledBack);
     };
-  }, [on, off, currentPick, userTeam, draftSlots, season.league.name]);
+  // `on`/`off` are stable useCallback refs — this effect runs once per socket instance.
+  // `draftSlots`, `userTeam`, and `season.league.name` are intentionally omitted: they
+  // come from useLoaderData and are immutable for the lifetime of the page load.
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [on, off]);
 
   // Persist sidebar collapsed state
   useEffect(() => {

app/routes/test-socket.tsx

@@ -3,7 +3,7 @@ import { useDraftSocket } from "~/hooks/useDraftSocket";
 
 export default function TestSocket() {
   const [messages, setMessages] = useState<string[]>([]);
-  const { socket, isConnected, on, off } = useDraftSocket("test-season-123");
+  const { isConnected, on, off, emit } = useDraftSocket("test-season-123");
 
   useEffect(() => {
     // Listen for test messages
@@ -20,13 +20,11 @@ export default function TestSocket() {
   }, [on, off]);
 
   const sendTestMessage = () => {
-    if (socket) {
-      socket.emit("test-event", {
+    emit("test-event", {
       message: "Hello from client!",
       timestamp: new Date().toISOString(),
     });
     setMessages((prev) => [...prev, "Sent: Hello from client!"]);
-    }
   };
 
   return (
@@ -44,11 +42,6 @@ export default function TestSocket() {
             Status: {isConnected ? "Connected" : "Disconnected"}
           </span>
         </div>
-        {socket && (
-          <p className="text-sm text-muted-foreground mt-1">
-            Socket ID: {socket.id}
-          </p>
-        )}
       </div>
 
       <button

server/socket.ts

@@ -76,6 +76,13 @@ export function initializeSocketIO(httpServer: HTTPServer): SocketIOServer {
 
   // Create typed Socket.IO server
   io = new SocketIOServer<ClientToServerEvents, ServerToClientEvents>(httpServer, {
+    // Faster dead-connection detection than the defaults (20s/25s).
+    // pingTimeout: how long to wait for a pong before declaring the connection dead.
+    // pingInterval: how often to send a ping.
+    // Together these detect a crashed server in ~15s instead of ~45s.
+    // Trade-off: more heartbeat traffic at scale; revisit if server load becomes a concern.
+    pingTimeout: 5000,
+    pingInterval: 10000,
     cors: process.env.NODE_ENV === "production" && process.env.APP_URL
       ? {
           origin: process.env.APP_URL,