fix: keep rapid telegram follow-ups from getting cut off

gateway/platforms/base.py

@@ -734,25 +734,56 @@ def merge_pending_message_event(
     pending_messages: Dict[str, MessageEvent],
     session_key: str,
     event: MessageEvent,
+    *,
+    merge_text: bool = False,
 ) -> None:
     """Store or merge a pending event for a session.
 
     Photo bursts/albums often arrive as multiple near-simultaneous PHOTO
     events. Merge those into the existing queued event so the next turn sees
-    the whole burst, while non-photo follow-ups still replace the pending
-    event normally.
+    the whole burst.
+
+    When ``merge_text`` is enabled, rapid follow-up TEXT events are appended
+    instead of replacing the pending turn. This is used for Telegram bursty
+    follow-ups so a multi-part user thought is not silently truncated to only
+    the last queued fragment.
     """
     existing = pending_messages.get(session_key)
-    if (
-        existing
-        and getattr(existing, "message_type", None) == MessageType.PHOTO
-        and event.message_type == MessageType.PHOTO
-    ):
-        existing.media_urls.extend(event.media_urls)
-        existing.media_types.extend(event.media_types)
-        if event.text:
-            existing.text = BasePlatformAdapter._merge_caption(existing.text, event.text)
-        return
+    if existing:
+        existing_is_photo = getattr(existing, "message_type", None) == MessageType.PHOTO
+        incoming_is_photo = event.message_type == MessageType.PHOTO
+        existing_has_media = bool(existing.media_urls)
+        incoming_has_media = bool(event.media_urls)
+
+        if existing_is_photo and incoming_is_photo:
+            existing.media_urls.extend(event.media_urls)
+            existing.media_types.extend(event.media_types)
+            if event.text:
+                existing.text = BasePlatformAdapter._merge_caption(existing.text, event.text)
+            return
+
+        if existing_has_media or incoming_has_media:
+            if incoming_has_media:
+                existing.media_urls.extend(event.media_urls)
+                existing.media_types.extend(event.media_types)
+            if event.text:
+                if existing.text:
+                    existing.text = BasePlatformAdapter._merge_caption(existing.text, event.text)
+                else:
+                    existing.text = event.text
+            if existing_is_photo or incoming_is_photo:
+                existing.message_type = MessageType.PHOTO
+            return
+
+        if (
+            merge_text
+            and getattr(existing, "message_type", None) == MessageType.TEXT
+            and event.message_type == MessageType.TEXT
+        ):
+            if event.text:
+                existing.text = f"{existing.text}\n{event.text}" if existing.text else event.text
+            return
+
     pending_messages[session_key] = event