修改

src/service/platform/chat.service.ts

@@ -19,6 +19,7 @@ export class ChatService extends BaseService<modelType> {
     const user = this.ctx.user;
     const list = await this.model.aggregate([
       { $match: { ...filter, $or: [{ sender_id: get(user, '_id') }, { receiver_id: get(user, '_id') }] } },
+      { $sort: { send_time: -1 } },
       { $group: { _id: { sender_id: '$sender_id', receiver_id: '$receiver_id' }, other: { $first: '$$ROOT' } } },
       { $replaceRoot: { newRoot: '$other' } },
     ]);