Fixup call detection logic to allow sticky events

src/home/useGroupCallRooms.ts

@@ -114,19 +114,41 @@ const roomIsJoinable = (room: Room): boolean => {
   }
 };
 
+/**
+ * Determines if a given room has call events in it, and therefore
+ * is likely to be a call room.
+ * @param room The Matrix room instance.
+ * @returns `true` if the room has call events.
+ */
 const roomHasCallMembershipEvents = (room: Room): boolean => {
-  switch (room.getMyMembership()) {
-    case KnownMembership.Join:
-      return !!room
-        .getLiveTimeline()
-        .getState(EventTimeline.FORWARDS)
-        ?.events?.get(EventType.GroupCallMemberPrefix);
-    case KnownMembership.Knock:
-      // Assume that a room you've knocked on is able to hold calls
-      return true;
-    default:
-      return false;
+  // Legacy events.
+  const myMembership = room.getMyMembership();
+  if (myMembership === KnownMembership.Knock) {
+    // Assume that a room you've knocked on is able to hold calls
+    return true;
+  } else if (myMembership !== KnownMembership.Join) {
+    // Otherwise, non-joined rooms should never show up.
+    return false;
   }
+
+  const timeline = room.getLiveTimeline();
+
+  // Check legacy events first, because it's cheaper.
+  if (
+    timeline
+      .getState(EventTimeline.FORWARDS)
+      ?.events?.has(EventType.GroupCallMemberPrefix)
+  ) {
+    return true;
+  }
+
+  // There was call membership events at some point in the timeline.
+  return timeline.getEvents().some(
+    (e) =>
+      // Membership events only count if both of these are true
+      e.unstableStickyInfo && e.getType() === EventType.GroupCallMemberPrefix,
+  );
+  // Otherwise, it's *unlikely* this room was ever a call.
 };
 
 export function useGroupCallRooms(client: MatrixClient): GroupCallRoom[] {
@@ -137,7 +159,7 @@ export function useGroupCallRooms(client: MatrixClient): GroupCallRoom[] {
       // We want to show all rooms that historically had a call and which we are (or can become) part of.
       const rooms = client
         .getRooms()
-        // .filter(roomHasCallMembershipEvents)
+        .filter(roomHasCallMembershipEvents)
         .filter(roomIsJoinable);
       const sortedRooms = sortRooms(client, rooms);
       Promise.all(