agent.py

from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_core.messages import HumanMessage, SystemMessage, AnyMessage
from typing import TypedDict, Annotated
from langgraph.graph.message import add_messages
from langgraph.prebuilt import ToolNode
from langgraph.graph import START, StateGraph
from langgraph.prebuilt import tools_condition
from tools import tools

model = ChatGoogleGenerativeAI(model="gemini-2.5-flash", temperature=0)
model_with_tools = model.bind_tools(tools)

system_template = "You are a general AI assistant. I will ask you a question. 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):
    return {
        "messages": [model_with_tools.invoke(state["messages"])],
    }

## The graph
builder = StateGraph(AgentState)

# Define nodes: these do the work
builder.add_node("assistant", assistant)
builder.add_node("tools", ToolNode(tools))

# Define edges: these determine how the control flow moves
builder.add_edge(START, "assistant")
builder.add_conditional_edges(
    "assistant",
    # If the latest message requires a tool, route to tools
    # Otherwise, provide a direct response
    tools_condition,
)
builder.add_edge("tools", "assistant")
chat = builder.compile()

config = {"configurable": {"thread_id": "1"}}

def invoke_agent(query: str) -> str:
    """
    Invoke the agent with a given question.
    """
    response = chat.invoke({"messages": [HumanMessage(content=query)]})
    return response['messages'][-1].content