Show 'reconnecting' message when session warns we've hit a timeout

By using the new 'probablyLeft' state provided by MatrixRTCSession.

src/state/CallViewModel.ts

@@ -57,6 +57,7 @@ import {
   type CallMembership,
   type MatrixRTCSession,
   MatrixRTCSessionEvent,
+  MembershipManagerEvent,
 } from "matrix-js-sdk/lib/matrixrtc";
 
 import { ViewModel } from "./ViewModel";
@@ -517,6 +518,19 @@ export class CallViewModel extends ViewModel {
           ),
         ),
       ),
+      // Also watch out for warnings that we've likely hit a timeout and our
+      // delayed leave event is being sent (this condition is here because it
+      // provides an earlier warning than the sync loop timeout, and we wouldn't
+      // see the actual leave event until we reconnect to the sync loop)
+      (
+        fromEvent(
+          this.matrixRTCSession,
+          MembershipManagerEvent.ProbablyLeft,
+        ) as Observable<[SyncState]>
+      ).pipe(
+        startWith([false]),
+        map(([probablyLeft]) => !probablyLeft),
+      ),
     ),
   );