agent.py

import os
from typing import TypedDict, Annotated 
from langgraph.graph.message import add_messages 
from langchain_core.messages import AnyMessage, SystemMessage
from langgraph.prebuilt import ToolNode, tools_condition
from langgraph.graph import START, StateGraph
from langchain_openai import ChatOpenAI
# from langchain_google_genai import ChatGoogleGenerativeAI

from tools import tavily_search_tool, repl_tool

OPENAI_API_KEY = os.environ.get("OPENAI_API_KEY")
# GOOGLE_API_KEY = os.environ.get("GOOGLE_API_KEY")

chat_model = ChatOpenAI(model='gpt-4.1', temperature=0, api_key=OPENAI_API_KEY)
# chat_model = ChatGoogleGenerativeAI(model="gemini-2.0-flash", google_api_key=GOOGLE_API_KEY)
tools = [tavily_search_tool, repl_tool]
chat_model_with_tools = chat_model.bind_tools(tools)

SYSTEM_MESSAGE = """
You are a general AI assistant. I will ask you a question. Answer the question 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. If you are asked for a number, don't use comma to 
write your number neither use units such as $ or percent sign unless specified otherwise. If you are asked for a string, don't use articles, neither abbreviations (e.g. for cities), 
and write the digits in plain text unless specified otherwise. If you are asked for a comma separated list, apply the above rules depending of whether the element to be 
put in the list is a number or a string. 
"""

class AgentState(TypedDict):
    messages: Annotated[list[AnyMessage], add_messages]

def assistant(state: AgentState):
    sys_msg = SystemMessage(content=SYSTEM_MESSAGE)
    return {
        "messages": [chat_model_with_tools.invoke([sys_msg] + state["messages"])]
    }

graph_builder = StateGraph(AgentState)

graph_builder.add_node("assistant", assistant)
graph_builder.add_node("tools", ToolNode(tools))

graph_builder.add_edge(START, "assistant")
graph_builder.add_conditional_edges(
    "assistant",
    tools_condition,
)
graph_builder.add_edge("tools", "assistant")
graph = graph_builder.compile()