Reading agent state - Copilotkit

<Callout type="info"> This example demonstrates reading from shared state in the [CopilotKit Feature Viewer](https://feature-viewer.copilotkit.ai/llama-index/feature/shared_state). </Callout>

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

<Steps> <Step> ### Run and connect your agent <RunAndConnect /> </Step> <Step> ### Define the Agent State

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

```python title="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__":
    uvicorn.run(app, host="localhost", port=8000)
```

</Step> <Step> ### 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 optionally provide an initial state.

```tsx title="ui/app/page.tsx"
"use client";


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

function YourMainContent() {
  // [!code highlight:4]
  const { agent } = useAgent({
    agentId: "my_agent",
    initialState: { language: "english" }  // optionally provide an initial state
  });

  // ...

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

<Callout type="warn" title="Important">
  The `name` parameter must exactly match the agent name you defined in your CopilotRuntime configuration (e.g., `my_agent` from the quickstart).
</Callout>

<Callout type="info">
  The `agent.state` in `useAgent` is reactive and will automatically update when the agent's state changes.
</Callout>

</Step> <Step> ### 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" as that's the initial state we set. </Step> </Steps>

Rendering agent state in the chat

You can also render the agent's state in the chat UI. This is useful for informing the user about the agent's state in a more in-context way. To do this, you can use the useAgent hook with a render function.

tsx

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

function YourMainContent() {
  // ...
  // [!code highlight:7]
  useAgent({
    agentId: "my_agent",
    render: ({ state }) => {
      if (!state.language) return null;
      return <div>Language: {state.language}</div>;
    },
  });
  // ...
}

<Callout type="warn" title="Important"> The `name` parameter must exactly match the agent name you defined in your CopilotRuntime configuration (e.g., `my_agent` from the quickstart). </Callout> <Callout type="info"> The `agent.state` in `useAgent` is reactive and will automatically update when the agent's state changes. </Callout>