Update latest code

backend/agent/controller.py

@@ -16,6 +16,7 @@ from common.conversation_manager import ConversationManager, get_conversation_ma
 from common.langfuse_client import get_callback_handler
 from common.llm_factory import create_llm
 from config import DEFAULT_MODEL
+from langfuse import propagate_attributes
 
 from .graph import build_graph
 from .models import AgentState, get_config
@@ -110,9 +111,14 @@ async def chat_controller(
         callbacks=[langfuse_handler] if langfuse_handler else [],
     )
 
-    # Execute graph
+    # Execute graph với Langfuse user tracking
+    # Dùng propagate_attributes để tự động gán user_id cho tất cả observations
     start_time = time.time()
-    result = await graph.ainvoke(initial_state, config=exec_config)
+    # Generate session_id từ user_id + run_id (có thể thay bằng conversation_id nếu có)
+    session_id = f"{user_id}-{run_id[:8]}"
+    
+    with propagate_attributes(user_id=user_id, session_id=session_id):
+        result = await graph.ainvoke(initial_state, config=exec_config)
     duration = time.time() - start_time
 
     # Parse AI response (expected JSON from chat_controller logic)