Update agent_lang.py

agent_lang.py

@@ -0,0 +1,31 @@
+import os
+from langgraph.graph import StateGraph, END
+from langchain_core.runnables import Runnable
+from langchain_core.messages import HumanMessage
+from langchain_core.runnables import RunnableLambda
+from langchain_openai import ChatOpenAI
+
+class LangGraphAgent:
+    def __init__(self):
+        print("LangGraphAgent initialized.")
+
+        open_key = os.environ.get("OPEN_AI_KEY")
+
+        # Define a simple LangGraph that uses OpenAI to answer questions
+        self.llm = ChatOpenAI(model="gpt-4.1", temperature=0, api_key=open_key))
+        
+        def answer_fn(state):
+            question = state["question"]
+            print(f"[LangGraphAgent] Received: {question[:50]}...")
+            response = self.llm.invoke([HumanMessage(content=question)])
+            return {"answer": response.content}
+
+        builder = StateGraph(state={"question": str, "answer": str})
+        builder.add_node("answer_question", RunnableLambda(answer_fn))
+        builder.set_entry_point("answer_question")
+        builder.set_finish_point("answer_question")
+        self.graph = builder.compile()
+
+    def __call__(self, question: str) -> str:
+        output = self.graph.invoke({"question": question})
+        return output["answer"]