agent/graph.py

from typing import Annotated, Optional
from langgraph.graph import StateGraph, MessagesState, START, END
from langchain_core.messages import HumanMessage, AIMessage, SystemMessage
from langgraph.prebuilt import ToolNode, tools_condition
from langchain_ollama import ChatOllama
from agent.tools import TOOLS

class State(MessagesState):
    file_path: str

model = ChatOllama(model="qwen3:32b")
#model = ChatOllama(model="llama3.2:3b")
model_with_tools = model.bind_tools(TOOLS)

def call_model(state: State):
    return {"messages": [AIMessage(content="FINAL ANSWER: right")]}
    system_prompt = """
    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. 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.
    
    Instructions for the tools:
    - If you need information from the web, you must use both the web_search and wikipedia_search tools, unless the question mentions wikipedia. Then, you must use only the wikipedia_search tool.

    Do not forget to use the FINAl ANSWER: [YOUR FINAL ANSWER] template!!!
    """
    if state["file_path"] and state["file_path"] != "":
        system_prompt += f"\n\nYou have acces to a file at {state['file_path']}. You can use it to answer the question. Use this file path as input to relevant tools."

    result = model_with_tools.invoke([SystemMessage(content=system_prompt)] + state["messages"])
    
    return {"messages": [result]}


def build_agent():
    graph_builder = StateGraph(State)

    graph_builder.add_node("call_model", call_model)
    graph_builder.add_node("tools", ToolNode(TOOLS))
    graph_builder.add_edge(START, "call_model")
    graph_builder.add_conditional_edges("call_model", tools_condition)
    graph_builder.add_edge("tools", "call_model")

    return graph_builder.compile()

if __name__ == "__main__":
    # Example usage
    agent = build_agent()
    output = agent.invoke({"messages": [HumanMessage(content="Hello, how are you?")]})
    for msg in output["messages"]:
        msg.pretty_print()