fix(telegram): support threads in DMs

nanobot/channels/telegram.py

@@ -599,11 +599,15 @@ class TelegramChannel(BaseChannel):
             return
 
         now = time.monotonic()
+        thread_kwargs = {}
+        if message_thread_id := meta.get("message_thread_id"):
+            thread_kwargs["message_thread_id"] = message_thread_id
         if buf.message_id is None:
             try:
                 sent = await self._call_with_retry(
                     self._app.bot.send_message,
                     chat_id=int_chat_id, text=buf.text,
+                    **thread_kwargs,
                 )
                 buf.message_id = sent.message_id
                 buf.last_edit = now
@@ -651,9 +655,9 @@ class TelegramChannel(BaseChannel):
 
     @staticmethod
     def _derive_topic_session_key(message) -> str | None:
-        """Derive topic-scoped session key for non-private Telegram chats."""
+        """Derive topic-scoped session key for Telegram chats with threads."""
         message_thread_id = getattr(message, "message_thread_id", None)
-        if message.chat.type == "private" or message_thread_id is None:
+        if message_thread_id is None:
             return None
         return f"telegram:{message.chat_id}:topic:{message_thread_id}"
 
@@ -815,7 +819,7 @@ class TelegramChannel(BaseChannel):
         return bool(bot_id and reply_user and reply_user.id == bot_id)
 
     def _remember_thread_context(self, message) -> None:
-        """Cache topic thread id by chat/message id for follow-up replies."""
+        """Cache Telegram thread context by chat/message id for follow-up replies."""
         message_thread_id = getattr(message, "message_thread_id", None)
         if message_thread_id is None:
             return