Reading agent state

This example demonstrates reading from shared state in the CopilotKit Feature Viewer.

What is this?#

You can easily use the realtime agent state not only in the chat UI, but also in the native application UX.

When should I use this?#

You can use this when you want to provide the user with feedback about your agent's state. As your agent's state updates, you can reflect these updates natively in your application.

Implementation#

Run and connect your agent#

You'll need to run your agent and connect it to CopilotKit before proceeding. If you haven't done so already, you can follow the instructions in the Getting Started guide.

If you don't already have an agent, you can use the coagent starter as a starting point as this guide uses it as a starting point.

Define the Agent State#

Create your LlamaIndex agent with a stateful structure using initial_state. Here's a complete example that tracks language:

agent.py

from fastapi import FastAPI
from llama_index.llms.openai import OpenAI
from llama_index.protocols.ag_ui.router import get_ag_ui_workflow_router

# Initialize the LLM
llm = OpenAI(model="gpt-5.4")

# Create the AG-UI workflow router
agentic_chat_router = get_ag_ui_workflow_router(
    llm=llm,
    system_prompt="""
    You are a helpful assistant for tracking the language.

    IMPORTANT:
    - ALWAYS use the lower case for the language
    - ALWAYS respond in the current language from the state
    """,
    initial_state={
        "language": "english"
    },
)

# Create FastAPI app
app = FastAPI(
    title="LlamaIndex Agent",
    description="A LlamaIndex agent integrated with CopilotKit",
    version="1.0.0"
)

# Include the router
app.include_router(agentic_chat_router)

# Health check endpoint
@app.get("/health")
async def health_check():
    return {"status": "healthy", "agent": "llamaindex"}

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="localhost", port=8000)

Use the `useAgent` Hook#

With your agent connected and running all that is left is to call the useAgent hook, pass the agent's name, and initialize missing UI-owned state after the connected agent is ready.

ui/app/page.tsx

"use client";

import { useEffect } from "react";
import { useAgent } from "@copilotkit/react-core/v2"; 

// Define the agent state type, should match the actual state of your agent
type AgentState = {
language: "english" | "spanish";
}

function YourMainContent() {
  const { agent, isReady } = useAgent({
    agentId: "my_agent",
  });
  const state = (agent.state ?? {}) as Partial<AgentState>;

  useEffect(() => {
if (!isReady || state.language !== undefined) return;
    agent.setState({ ...(agent.state ?? {}), language: "english" });
  }, [agent, isReady, state.language]);

  // ...

  return (
    // style excluded for brevity
    <div>
      <h1>Your main content</h1>
      <p>Language: {agent.state?.language}</p>
    </div>
  );
}

Important

The name parameter must exactly match the agent name you defined in your CopilotRuntime configuration (e.g., my_agent from the quickstart).

The agent.state in useAgent is reactive and will automatically update when the agent's state changes.

Give it a try!#

As the agent state updates, your state variable will automatically update with it! In this case, you'll see the language set to "english" after the connected agent is ready.

Rendering agent state in your app#

You can render the agent state in any React component under <CopilotKit>. Read agent.state and return ordinary JSX.