Final submission: update main.py

main.py

@@ -15,14 +15,18 @@ def echo(text: str) -> str:
 
 # Define graph state
 class State(dict):
-    pass
+    pass  # no-op
+
+# Dummy tool node to satisfy interrupt_before
+async def tools_node(state: State, config=None):
+    return state
 
 # Agent node
 async def agent_node(state: State, config=None):
     # Use LangChain LLM with tool calling
     llm = ChatOpenAI(model="gpt-4o-mini", temperature=0)
-    from langchain.agents import create_openai_functions_agent
-    agent = create_openai_functions_agent(llm, [echo])
+    from langgraph.agent import create_agent
+    agent = create_agent(llm, [echo])
     messages = state.get("messages", [])
     # Run agent
     result = await agent.ainvoke({"messages": messages})
@@ -32,6 +36,7 @@ async def agent_node(state: State, config=None):
 builder = StateGraph(State)
 builder.add_node("agent", agent_node)
 builder.set_entry_point("agent")
+builder.add_node("tools", tools_node)
 
 graph = builder.compile(checkpointer=MemorySaver(), interrupt_before=["tools"])  # memory and pause before tools