Make room switches instant and cut redundant client work.

Keep-alive room cache with CSS-only warm switches, nav loading feedback, and per-context members drawer prefs. Share hierarchy/call/sub-room subscriptions, demux state events, and lazy lobby power-level loading to avoid duplicate scans and listener storms.

src/app/features/call/useCall.ts

@@ -230,62 +230,76 @@ export function useCallService(): CallContextValue {
 /**
  * Hook to check if a call is active in a specific room
  */
+/** Persists across keep-alive remounts so room switches don't re-hit well-known. */
+const roomCallSupportCache = new Map<string, boolean>();
+
 export function useRoomCall(roomId: string) {
   const { activeCall, startCall, endCall, callSupported: globalCallSupported, callSupportLoading: globalCallSupportLoading, callService } = useCall();
   const mx = useMatrixClient();
-  const [roomCallSupported, setRoomCallSupported] = useState(false);
-  const [roomCallSupportLoading, setRoomCallSupportLoading] = useState(true);
+  const [roomCallSupported, setRoomCallSupported] = useState(
+    () => roomCallSupportCache.get(roomId) ?? false
+  );
+  const [roomCallSupportLoading, setRoomCallSupportLoading] = useState(
+    () => !roomCallSupportCache.has(roomId)
+  );
 
   // Check if calls are supported for this specific room by checking all priority homeservers
   useEffect(() => {
+    const cached = roomCallSupportCache.get(roomId);
+    if (cached !== undefined) {
+      setRoomCallSupported(cached);
+      setRoomCallSupportLoading(false);
+      return undefined;
+    }
+
+    let cancelled = false;
+
     const checkRoomCallSupport = async () => {
       setRoomCallSupportLoading(true);
-      
+
       const room = mx.getRoom(roomId);
       if (!room) {
-        setRoomCallSupported(false);
-        setRoomCallSupportLoading(false);
+        if (!cancelled) {
+          setRoomCallSupported(false);
+          setRoomCallSupportLoading(false);
+        }
         return;
       }
 
-      // Get homeserver priority list for this room
       const homeserverPriority = getLiveKitHomeserverPriority(
         room,
         mx.getHomeserverUrl(),
         mx.getSafeUserId()
       );
 
-      console.log(`Checking call support for room ${roomId}, homeserver priority:`, homeserverPriority);
-
-      // Check each homeserver in priority order
       for (const homeserver of homeserverPriority) {
         try {
-          console.log(`Fetching well-known from ${homeserver}...`);
           const wellKnown = await fetchWellKnownWithRTC(homeserver);
-          console.log(`Well-known response from ${homeserver}:`, wellKnown);
-          
           const livekitFocus = getLiveKitFocus(wellKnown);
-          console.log(`LiveKit focus from ${homeserver}:`, livekitFocus);
-          
           if (livekitFocus) {
-            console.log(`Call support found for room ${roomId} on homeserver: ${homeserver}`);
-            setRoomCallSupported(true);
-            setRoomCallSupportLoading(false);
+            roomCallSupportCache.set(roomId, true);
+            if (!cancelled) {
+              setRoomCallSupported(true);
+              setRoomCallSupportLoading(false);
+            }
             return;
           }
-        } catch (error) {
-          console.warn(`Failed to check call support on ${homeserver}:`, error);
+        } catch {
           // Continue to next homeserver
         }
       }
 
-      // No homeserver supports calls
-      console.log(`No call support found for room ${roomId}`);
-      setRoomCallSupported(false);
-      setRoomCallSupportLoading(false);
+      roomCallSupportCache.set(roomId, false);
+      if (!cancelled) {
+        setRoomCallSupported(false);
+        setRoomCallSupportLoading(false);
+      }
     };
 
     checkRoomCallSupport();
+    return () => {
+      cancelled = true;
+    };
   }, [roomId, mx]);
 
   const isInCall = activeCall?.roomId === roomId;