quick nit

This reverts commit 26a71d40b6.

backend/onyx/chat/process_message.py

@@ -73,6 +73,7 @@ from onyx.db.chat import get_or_create_root_message
 from onyx.db.chat import reserve_message_id
 from onyx.db.chat import translate_db_message_to_chat_message_detail
 from onyx.db.chat import translate_db_search_doc_to_server_search_doc
+from onyx.db.chat import update_chat_session_updated_at_timestamp
 from onyx.db.engine import get_session_context_manager
 from onyx.db.milestone import check_multi_assistant_milestone
 from onyx.db.milestone import create_milestone_if_not_exists
@@ -1069,6 +1070,8 @@ def stream_chat_message_objects(
             prev_message = next_answer_message
 
         logger.debug("Committing messages")
+        # Explicitly update the timestamp on the chat session
+        update_chat_session_updated_at_timestamp(chat_session_id, db_session)
         db_session.commit()  # actually save user / assistant message
 
         yield AgenticMessageResponseIDInfo(agentic_message_ids=agentic_message_ids)

backend/onyx/db/chat.py

@@ -1089,3 +1089,20 @@ def log_agent_sub_question_results(
             db_session.commit()
 
     return None
+
+
+def update_chat_session_updated_at_timestamp(
+    chat_session_id: UUID, db_session: Session
+) -> None:
+    """
+    Explicitly update the timestamp on a chat session without modifying other fields.
+    This is useful when adding messages to a chat session to reflect recent activity.
+    """
+
+    # Direct SQL update to avoid loading the entire object if it's not already loaded
+    db_session.execute(
+        update(ChatSession)
+        .where(ChatSession.id == chat_session_id)
+        .values(time_updated=func.now())
+    )
+    # No commit - the caller is responsible for committing the transaction