🐛(frontend) add LiveKit connection warmup for Firefox+proxy fixes

Implement HTTPS prefetch before joining rooms to resolve WebSocket
handshake failures where Firefox+proxy returns HTTP 200 instead of 101.

Reproduced locally with Squid container. No proxy configuration fixes
found - HTTPS warmup is only working workaround. Issue doesn't occur
when signaling server shares webapp domain, making warmup unnecessary.

Use HEAD request to minimize bandwidth.

Author: lebaudantoine

src/backend/core/api/__init__.py

@@ -50,6 +50,7 @@ def get_frontend_configuration(request):
             else None,
             "default_country": settings.ROOM_TELEPHONY_DEFAULT_COUNTRY,
         },
+        "livekit": {"url": settings.LIVEKIT_CONFIGURATION["url"]},
     }
     frontend_configuration.update(settings.FRONTEND_CONFIGURATION)
     return Response(frontend_configuration)

src/frontend/src/api/useConfig.ts

@@ -37,6 +37,9 @@ export interface ApiConfig {
     default_country?: string
   }
   manifest_link?: string
+  livekit: {
+    url: string
+  }
 }
 
 const fetchConfig = (): Promise<ApiConfig> => {

src/frontend/src/features/rooms/components/Conference.tsx

@@ -24,6 +24,7 @@ import { LocalUserChoices } from '@/stores/userChoices'
 import { navigateTo } from '@/navigation/navigateTo'
 import { MediaDeviceErrorAlert } from './MediaDeviceErrorAlert'
 import { usePostHog } from 'posthog-js/react'
+import { useConfig } from '@/api/useConfig'
 
 export const Conference = ({
   roomId,
@@ -37,12 +38,15 @@ export const Conference = ({
   initialRoomData?: ApiRoom
 }) => {
   const posthog = usePostHog()
+  const { data: apiConfig } = useConfig()
 
   useEffect(() => {
     posthog.capture('visit-room', { slug: roomId })
   }, [roomId, posthog])
   const fetchKey = [keys.room, roomId]
 
+  const [isConnectionWarmedUp, setIsConnectionWarmedUp] = useState(false)
+
   const {
     mutateAsync: createRoom,
     status: createStatus,
@@ -53,6 +57,36 @@ export const Conference = ({
     },
   })
 
+  /**
+   * Warm up connection to LiveKit server before joining room
+   * This prefetch helps reduce initial connection latency by establishing
+   * an early HTTP connection to the WebRTC signaling server
+   *
+   * FIREFOX + PROXY WORKAROUND:
+   * On Firefox behind proxy configurations, WebSocket signaling fails to establish.
+   * Client receives HTTP 200 instead of expected 101 (Switching Protocols).
+   * This appears to be a certificate/security issue where the initial request
+   * is considered unsecure. By first calling the signaling server via HTTPS,
+   * subsequent WebSocket establishment works correctly in these setups.
+   * This is a temporary workaround - issue is reproducible on LiveKit's demo app.
+   */
+  useEffect(() => {
+    const warmUpLivekitConnection = async () => {
+      if (isConnectionWarmedUp || !apiConfig) return
+      try {
+        // Make a lightweight HTTPS request to establish secure connection
+        // This resolves Firefox+proxy WebSocket handshake issues
+        await fetch(apiConfig.livekit.url, { method: 'HEAD' })
+        setIsConnectionWarmedUp(true)
+      } catch (error) {
+        // Don't block room connection if warmup fails
+        console.warn('LiveKit connection warmup failed:', error)
+        setIsConnectionWarmedUp(true)
+      }
+    }
+    warmUpLivekitConnection()
+  }, [isConnectionWarmedUp, apiConfig])
+
   const {
     status: fetchStatus,
     isError: isFetchError,
@@ -125,9 +159,9 @@ export const Conference = ({
       <Screen header={false} footer={false}>
         <LiveKitRoom
           room={room}
-          serverUrl={data?.livekit?.url}
+          serverUrl={apiConfig?.livekit.url}
           token={data?.livekit?.token}
-          connect={true}
+          connect={isConnectionWarmedUp}
           audio={userConfig.audioEnabled}
           video={
             userConfig.videoEnabled && {