fix(telegram): route resumed DM topic sends via direct_messages_topic_id

gateway/platforms/base.py

@@ -45,17 +45,20 @@ def _thread_metadata_for_source(source, reply_to_message_id: str | None = None)
 
     Most platforms route threaded sends with a generic ``thread_id`` metadata
     value. Telegram private-chat topics created through Hermes' DM-topic helper
-    are exposed in updates as ``message_thread_id`` plus a reply anchor, but
-    outbound sends only render in the correct Telegram lane when the adapter
-    supplies both ``message_thread_id`` and ``reply_to_message_id``. Mark those
-    lanes so the Telegram adapter can avoid the known-bad partial routes.
+    are exposed in updates as ``message_thread_id`` plus a reply anchor. Live
+    user-message replies route with ``message_thread_id`` + ``reply_to_message_id``;
+    synthetic/resumed sends that have no reply anchor fall back to Telegram's
+    ``direct_messages_topic_id`` when the Bot API supports it.
     """
     thread_id = getattr(source, "thread_id", None)
     if thread_id is None:
         return None
     metadata = {"thread_id": thread_id}
     if _platform_name(getattr(source, "platform", None)) == "telegram" and getattr(source, "chat_type", None) == "dm":
         metadata["telegram_dm_topic_reply_fallback"] = True
+        tid = str(thread_id)
+        if tid and tid not in {"", "1"}:
+            metadata["direct_messages_topic_id"] = tid
         anchor = reply_to_message_id or getattr(source, "message_id", None)
         if anchor is not None:
             metadata["telegram_reply_to_message_id"] = str(anchor)
@@ -67,10 +70,9 @@ def _reply_anchor_for_event(event) -> str | None:
 
     Telegram forum/supergroup topics should be routed by topic metadata, not by
     replying to the triggering message. Hermes-created Telegram private-chat
-    topic lanes are different: Bot API sends reject their ``message_thread_id``
-    and do not route with ``direct_messages_topic_id``. Those lanes only remain
-    visible when sent with both the private topic thread id and a reply to the
-    triggering user message.
+    topic lanes prefer replying to the triggering user message so the answer
+    stays attached to the active lane; synthetic/resumed sends fall back to
+    ``direct_messages_topic_id`` metadata when no message id is available.
     """
     source = getattr(event, "source", None)
     platform = _platform_name(getattr(source, "platform", None))

gateway/platforms/telegram.py

@@ -560,9 +560,10 @@ def _thread_kwargs_for_send(
         Supergroup/forum topics use ``message_thread_id``. True Bot API Direct
         Messages topics can opt in with explicit ``direct_messages_topic_id``
         metadata. Hermes-created private-chat topic lanes are marked with
-        ``telegram_dm_topic_reply_fallback`` and must send the private topic
-        thread id together with a reply anchor. Live testing showed that either
-        parameter alone can render outside the visible lane.
+        ``telegram_dm_topic_reply_fallback``. Live replies send the private
+        topic thread id together with a reply anchor; synthetic/resumed sends
+        without an anchor use ``direct_messages_topic_id`` when metadata has it.
+        ``message_thread_id`` alone can render outside the visible lane.
 
         When ``reply_to_mode`` is ``"off"``, the reply anchor is suppressed for
         DM topic fallback sends while preserving the ``message_thread_id`` so
@@ -574,6 +575,12 @@ def _thread_kwargs_for_send(
             if reply_to_message_id is None:
                 reply_to_message_id = cls._metadata_reply_to_message_id(metadata)
             if reply_to_message_id is None:
+                direct_topic_id = cls._metadata_direct_messages_topic_id(metadata)
+                if direct_topic_id is not None:
+                    return {
+                        "message_thread_id": None,
+                        "direct_messages_topic_id": int(direct_topic_id),
+                    }
                 return {}
             return {"message_thread_id": cls._message_thread_id_for_send(thread_id)}
         direct_topic_id = cls._metadata_direct_messages_topic_id(metadata)

tests/gateway/test_telegram_thread_fallback.py

@@ -331,10 +331,28 @@ def test_base_gateway_metadata_marks_telegram_dm_topics_as_reply_fallback():
     assert metadata == {
         "thread_id": "20189",
         "telegram_dm_topic_reply_fallback": True,
+        "direct_messages_topic_id": "20189",
         "telegram_reply_to_message_id": "462",
     }
 
 
+def test_base_gateway_metadata_for_resumed_telegram_dm_topic_uses_direct_topic():
+    """Resumed/synthetic DM-topic events may have no reply anchor."""
+    source = SimpleNamespace(
+        platform=Platform.TELEGRAM,
+        chat_type="dm",
+        thread_id="20189",
+    )
+
+    metadata = _thread_metadata_for_source(source)
+
+    assert metadata == {
+        "thread_id": "20189",
+        "telegram_dm_topic_reply_fallback": True,
+        "direct_messages_topic_id": "20189",
+    }
+
+
 def test_base_gateway_replies_to_triggering_message_for_telegram_dm_topic():
     """Private DM topic lanes should anchor replies to the active user message."""
     event = SimpleNamespace(
@@ -533,7 +551,7 @@ async def mock_send_message(**kwargs):
 
 @pytest.mark.asyncio
 async def test_send_dm_topic_fallback_without_anchor_does_not_crash():
-    """DM-topic fallback without an anchor must not use message_thread_id alone."""
+    """DM-topic fallback without an anchor uses direct topic routing."""
     adapter = _make_adapter()
     call_log = []
 
@@ -549,13 +567,14 @@ async def mock_send_message(**kwargs):
         metadata={
             "thread_id": "20197",
             "telegram_dm_topic_reply_fallback": True,
+            "direct_messages_topic_id": "20197",
         },
     )
 
     assert result.success is True
     assert call_log[0]["reply_to_message_id"] is None
-    assert "message_thread_id" not in call_log[0]
-    assert "direct_messages_topic_id" not in call_log[0]
+    assert call_log[0]["message_thread_id"] is None
+    assert call_log[0]["direct_messages_topic_id"] == 20197
 
 
 @pytest.mark.asyncio