Reading agent state

This video shows the result of npx copilotkit@latest init with the implementation section applied to it.

What is this?#

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

CopilotKit consumes AG-UI protocol events streamed by AG2 over /chat. See the AG2 AG-UI integration docs.

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#

Start your AG2 backend and connect your CopilotKit frontend to the AG-UI /chat endpoint.

Define the Agent State#

Create your AG2 backend with ContextVariables and emit StateSnapshotEvent whenever the state changes:

agent.py

from typing import Annotated

from ag_ui.core import EventType, StateSnapshotEvent
from fastapi import FastAPI, Header
from fastapi.responses import StreamingResponse
from autogen import ConversableAgent, LLMConfig
from autogen.agentchat import ContextVariables
from autogen.ag_ui import AGUIStream, RunAgentInput

def read_state(context: ContextVariables) -> dict:
    return context.get("agent_state", {"language": "english"})

def write_state(context: ContextVariables, state: dict) -> StateSnapshotEvent:
    context["agent_state"] = state
    return StateSnapshotEvent(type=EventType.STATE_SNAPSHOT, snapshot=state)

agent = ConversableAgent(
    name="assistant",
    system_message=(
        "You are a helpful assistant for tracking language. "
        "Always respond in the current language."
    ),
    llm_config=LLMConfig({"model": "gpt-5.4-mini"}),
    human_input_mode="NEVER",
)

@agent.register_for_llm(description="Update the language in shared state.")
def set_language(
    context: ContextVariables,
    language: Annotated[str, "language such as english or spanish"],
) -> StateSnapshotEvent:
    return write_state(context, {"language": language.lower()})

agent.register_for_execution(name="set_language")(set_language)

stream = AGUIStream(agent)
app = FastAPI()

@app.post("/chat")
async def run_agent(
    message: RunAgentInput,
accept: str | None = Header(None),
):
    return StreamingResponse(
        stream.dispatch(message, accept=accept),
        media_type=accept or "text/event-stream",
    )

Use the `useAgent` Hook#

With your agent connected and running all that is left is to call the useAgent hook, pass the agent's ID, and optionally provide an initial state.

ui/app/page.tsx

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 } = useAgent({
    agentId: "my_agent", // MUST match the agent name in CopilotRuntime
    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 agentId 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.