Trying to set up langgraph to add messages every time, not overwrite it

app.py

@@ -1,5 +1,6 @@
 import os
 from typing import TypedDict, List, Dict, Any, Optional, Tuple
+from typing_extensions import Annotated
 
 import gradio as gr
 import requests
@@ -12,7 +13,7 @@ from langgraph.prebuilt import ToolNode, tools_condition
 
 from langchain_openai import ChatOpenAI
 from langchain_community.tools import DuckDuckGoSearchRun
-from langchain_core.messages import SystemMessage, HumanMessage
+from langchain_core.messages import SystemMessage, HumanMessage, AnyMessage
 
 
 # --- Constants ---
@@ -20,7 +21,7 @@ DEFAULT_API_URL = "https://agents-course-unit4-scoring.hf.space"
 
 class State(TypedDict):
     question: str
-    messages: List[Dict[str, Any]]
+    messages: Annotated[List[AnyMessage], add_messages]
 
 
 class BasicAgent:
@@ -45,7 +46,24 @@ class BasicAgent:
 
     def __call__(self, question: str) -> Tuple[str, List[Dict[str, Any]]]:
         print(f"Agent received question: {question}")
-        state = State(question=question, messages=[HumanMessage(content=question)])
+
+        tool_doc = """
+        search_tool(question: str, max_length: int = 2048) -> str:
+            Search info on the web.
+        Args:
+            question: Question string
+            max_length: maximum characters in the output
+        Returns:
+            A single string containing the info from the web.
+        """
+        sys_msg = SystemMessage(
+            content=f"""You are a general AI assistant. I will ask you a question. Report your thoughts, and finish your answer with the following template: FINAL ANSWER: [YOUR FINAL ANSWER]. YOUR FINAL ANSWER should be a number OR as few words as possible OR a comma separated list of numbers and/or strings. You can use provided tools:\n{tool_doc}"""
+        )
+            
+        state = State(
+            question=question, 
+            messages=[sys_msg, HumanMessage(content=question)]
+        )
         result = self.compiled_graph.invoke(state)
         final_answer = result["messages"][-1].content
         print(f"Final Answer: {final_answer}")
@@ -53,31 +71,12 @@ class BasicAgent:
 
     def assistant(self, state: State):
         print("Assistant invoked. State:", state)
-        messages = state.get("messages", [])
-
-        # Add system message only once
-        if not any(isinstance(m, SystemMessage) for m in messages):
-            tool_doc = """
-search_tool(question: str, max_length: int = 2048) -> str:
-    Search info on the web.
-    Args:
-        question: Question string
-        max_length: maximum characters in the output
-    Returns:
-        A single string containing the info from the web.
-            """
-            sys_msg = SystemMessage(
-                content=f"""You are a general AI assistant. I will ask you a question. Report your thoughts, and finish your answer with the following template: FINAL ANSWER: [YOUR FINAL ANSWER]. YOUR FINAL ANSWER should be a number OR as few words as possible OR a comma separated list of numbers and/or strings. You can use provided tools:\n{tool_doc}"""
-            )
-            messages = [sys_msg] + messages
-
-        # Invoke model with tools (LangGraph handles tool routing)
+
         response = self.model_with_tools.invoke(messages)
         print("Assistant response:", response)
 
         return {
-            "question": state["question"],
-            "messages": add_messages(messages, [response]),
+            "messages": [response]
         }
 
     def search_tool(self, question: str, max_length: int = 2048) -> str: