model Message {
  id String @id @default(cuid())

  attachments Attachment[]

  reply_to_id String? // Nullable because not all messages are replies
  reply_to    Message?  @relation("MessageReplies", fields: [reply_to_id], references: [id])
  replies     Message[] @relation("MessageReplies")

  content         String
  sender_id       String
  conversation_id String
  sentAt          DateTime @default(now())

  sender       Benutzer     @relation(fields: [sender_id], references: [id])
  conversation Conversation @relation(fields: [conversation_id], references: [id])
}