model OnlineLog {
  id      String   @id @default(auto()) @map("_id") @db.ObjectId // 内部ID
  uid     Int       // 用户唯一ID
  day     Int       // 注册时间到现在的天数
  login   DateTime  // 登入时间
  logout  DateTime? // 登出时间
  ip      String[] // List<String> becomes String[] // IP
  beat    Int     // 心跳次数

  // Optional fields you commented out in Java
  // create   DateTime?
  // bind     Int?
  // device   Int?         // e.g., enum later if needed
  // channel  String?
  // machine  String?

  @@unique([uid, day], name: "uid_index")
  @@index([login], name: "login_index") // TTL index — needs manual handling outside Prisma
  @@index([day], name: "day_index")
}