Langgraph

pip install langgraph langchain-openai

npm install @langchain/langgraph @langchain/openai @langchain/core

from posthog.ai.langchain import CallbackHandler
from posthog import Posthog
posthog = Posthog(
    "<ph_project_token>",
    host="https://us.i.posthog.com"
)
callback_handler = CallbackHandler(
    client=posthog,
    distinct_id="user_123", # optional
    trace_id="trace_456", # optional
    properties={"conversation_id"

import { PostHog } from 'posthog-node';
import { LangChainCallbackHandler } from '@posthog/ai';
const phClient = new PostHog(
  '<ph_project_token>',
  { host: 'https://us.i.posthog.com' }
);
const callbackHandler = new LangChainCallbackHandler({
  client: phClient,

from langgraph.prebuilt import create_react_agent
from langchain_openai import ChatOpenAI
from langchain_core.tools import tool
@tool
def get_weather(city: str) -> str:
    """Get the weather for a given city."""
    return f"It's always sunny in {city}!"
model = ChatOpenAI(api_key="your_openai_api_key")
agent = create_react_agent(model, tools=[get_weather])
result = agent.invoke(
    {"messages": [{"role": "user", "content": "What's the weather in Paris?"}]},
    config={"callbacks": [callback_handler]}
)
print(result["messages"][-1].content)

import { createReactAgent } from '@langchain/langgraph/prebuilt';
import { ChatOpenAI } from '@langchain/openai';
import { tool } from '@langchain/core/tools';
import { z } from 'zod';
const getWeather = tool(
  (input