Writing agent state

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

What is this?#

This guide shows you how to write to your agent's state from your application.

When should I use this?#

You can use this when you want to provide the user with feedback about what your agent is doing, specifically when your agent is calling tools. CopilotKit allows you to fully customize how these tools are rendered in the chat.

Implementation#

Run and Connect Your Agent to CopilotKit#

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#

CrewAI Flows are stateful. As you transition through the flow, that state is updated and available to the next function. For this example, let's assume that our agent state looks something like this.

agent.py

from copilotkit.crewai import CopilotKitState
from typing import Literal

class AgentState(CopilotKitState):
    language: Literal["english", "spanish"] = "english"

Call `agent.setState` from the `useAgent` hook#

useAgent returns an agent object with a setState method that you can use to update the agent state. Calling this will update the agent state and trigger a rerender of anything that depends on the agent state.

ui/app/page.tsx


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

// Example usage in a pseudo React component
function YourMainContent() {
  const { agent } = useAgent({ 
    agentId: "sample_agent",
    initialState: { language: "english" }  // optionally provide an initial state
  });

  // ...

  const toggleLanguage = () => {
    agent.setState({ language: agent.state?.language === "english" ? "spanish" : "english" }); 
  };

  // ...

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

Give it a try!#

You can now use agent.setState to update the agent state and agent.state to read it. Try toggling the language button and talking to your agent. You'll see the language change to match the agent's state.

Advanced Usage#

Re-run the agent with a hint about what's changed#

The new agent state will be used next time the agent runs. If you want to re-run it manually, use copilotkit.runAgent().

The agent will be re-run with the latest updated state. You can also add a hint message before re-running.

ui/app/page.tsx


// ...

function YourMainContent() {
  const { agent } = useAgent({
    agentId: "sample_agent",
  });
  const { copilotkit } = useCopilotKit(); 

  // setup to be called when some event in the app occurs
  const toggleLanguage = async () => {
    const newLanguage = agent.state?.language === "english" ? "spanish" : "english";
    agent.setState({ language: newLanguage });

    // add a hint message and re-run the agent
    agent.addMessage({
      id: crypto.randomUUID(),
      role: "user",
      content: `the language has been updated to ${newLanguage}`,
    });
    await copilotkit.runAgent({ agent });
  };

  return (
    // ...
  );
}

Intermediately Stream and Render Agent State#

By default, the CrewAI Flow agent state will only update between CrewAI Flow node transitions -- which means state updates will be discontinuous and delayed.

You likely want to render the agent state as it updates continuously.

See predictive state updates.