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 ADK agent with a stateful structure. Here's a complete example that tracks language:

agent.py

from typing import Dict
from fastapi import FastAPI
from pydantic import BaseModel
from ag_ui_adk import ADKAgent, add_adk_fastapi_endpoint
from google.adk.agents import LlmAgent
from google.adk.tools import ToolContext


class AgentState(BaseModel):
    """State for the agent."""
    language: str = "english"


def set_language(tool_context: ToolContext, new_language: str) -> Dict[str, str]:
    """Sets the language preference for the user.

    Args:
        tool_context (ToolContext): The tool context for accessing state.
        new_language (str): The language to save in state.

    Returns:
        Dict[str, str]: A dictionary indicating success status and message.
    """
    tool_context.state["language"] = new_language
    return {"status": "success", "message": f"Language set to {new_language}"}


agent = LlmAgent(
    name="my_agent",
    model="gemini-2.5-flash",
    instruction="""
    You are a helpful assistant. Help users by answering their questions.
    Please use the language specified in state when responding to the user.
    You can set the language in state by using the set_language tool.
    """,
    tools=[set_language],
)

adk_agent = ADKAgent(
    adk_agent=agent,
    app_name="demo_app",
    user_id="demo_user",
    session_timeout_seconds=3600,
    use_in_memory_services=True,
)

app = FastAPI()
add_adk_fastapi_endpoint(app, adk_agent, path="/")

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", 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 optionally provide an initial state.

ui/app/page.tsx


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

function YourMainContent() {
  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>
  );
}

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" as that's the initial state we set.

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.