Function deriveConversationKey

packages/bot-telegram/src/interaction.ts:35–61

(
  message: {
    message_id: number;
    message_thread_id?: number;
    chat: { id: number | string; type: string; is_forum?: boolean };
    reply_to_message?: { message_id: number };
    from?: { id: number };
  },
  userId?: number,
)

 * clicking user's id so the key matches ingress).
 */
export function deriveConversationKey(
  message: {
    message_id: number;
    message_thread_id?: number;
    chat: { id: number | string; type: string; is_forum?: boolean };
    reply_to_message?: { message_id: number };
    from?: { id: number };
  },
  userId?: number,
): ConversationKey {
  const { chat } = message;
  const chatId = String(chat.id);

  if (chat.type === "private") {
    return { chatId, scope: DM_SCOPE };
  }

  // Treat message_thread_id as a forum topic ONLY in forum supergroups. In a
  // regular (non-forum) supergroup Telegram also sets message_thread_id on any
  // REPLY message (it doubles as the reply-thread id), so keying off it there
  // would defeat per-user keying (each reply would spawn a new conversation).
  if (message.message_thread_id !== undefined && message.chat?.is_forum) {
    return { chatId, scope: `topic:${message.message_thread_id}` };
  }

  return { chatId, scope: `user:${userId ?? message.from?.id ?? "unknown"}` };
}

/**
 * Map a Telegram `from` user to a PlatformUser.