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

tests/channels/test_telegram_channel.py

@@ -424,6 +424,23 @@ async def test_send_delta_incremental_edit_treats_not_modified_as_success() -> N
     assert channel._stream_bufs["123"].last_edit > 0.0
 
 
+@pytest.mark.asyncio
+async def test_send_delta_initial_send_keeps_message_in_thread() -> None:
+    channel = TelegramChannel(
+        TelegramConfig(enabled=True, token="123:abc", allow_from=["*"]),
+        MessageBus(),
+    )
+    channel._app = _FakeApp(lambda: None)
+
+    await channel.send_delta(
+        "123",
+        "hello",
+        {"_stream_delta": True, "_stream_id": "s:0", "message_thread_id": 42},
+    )
+
+    assert channel._app.bot.sent_messages[0]["message_thread_id"] == 42
+
+
 def test_derive_topic_session_key_uses_thread_id() -> None:
     message = SimpleNamespace(
         chat=SimpleNamespace(type="supergroup"),