fix and update

apps/frontend/lib/family-chat.ts

@@ -0,0 +1,30 @@
+import { ChatRoom, createChatRoom, fetchChatRooms } from '@/lib/api';
+
+export async function findOrCreateMemberChat(
+  groupId: string,
+  memberUserId: string,
+  memberName: string,
+  currentUserId: string,
+  token: string
+): Promise<ChatRoom> {
+  const response = await fetchChatRooms(groupId, token);
+  const rooms = response.rooms ?? [];
+  const existing = rooms.find(
+    (room) =>
+      room.type === 'GROUP' &&
+      room.members.length === 2 &&
+      room.members.some((member) => member.userId === memberUserId) &&
+      room.members.some((member) => member.userId === currentUserId)
+  );
+  if (existing) return existing;
+  return createChatRoom(groupId, memberName, [memberUserId], token);
+}
+
+export function roomDisplayLabel(room: ChatRoom, currentUserId: string) {
+  if (room.type === 'GENERAL') return room.name;
+  if (room.members.length === 2) {
+    const other = room.members.find((member) => member.userId !== currentUserId);
+    if (other) return other.displayName;
+  }
+  return room.name;
+}