v3: various improvements and fixes to real-time updates

src/contexts/WSContext.ts

@@ -58,6 +58,8 @@ export interface WSContextValue {
   lastUserEvent: UserEvent | null;
   unreadNotificationCount: number;
   lastNotification: Notification | null;
+  /** Increments on each WS reconnect so pages can backfill missed events. */
+  connectionEpoch: number;
   castVote: (dumpId: string) => void;
   removeVote: (dumpId: string) => void;
   castCommentLike: (commentId: string) => void;
@@ -85,6 +87,7 @@ export const WSContext = createContext<WSContextValue>({
   lastUserEvent: null,
   unreadNotificationCount: 0,
   lastNotification: null,
+  connectionEpoch: 0,
   castVote: () => {},
   removeVote: () => {},
   castCommentLike: () => {},