Writing agent state

This example demonstrates writing to shared state in the CopilotKit Feature Viewer.

What is this?#

You can easily write to your agent's state from your native application, allowing you to update the agent's state from your UI.

When should I use this?#

You can use this when you want to provide user input or control to your agent's state. As your application state changes, you can update the agent state to reflect these changes.

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.

Setup your agent with state#

Define your agent's state schema. AWS Strands maintains state throughout execution.

agent/main.py

from ag_ui_strands import StrandsAgent, StrandsAgentConfig, create_strands_app
from strands import Agent
from strands.models.openai import OpenAIModel

model = OpenAIModel(
    client_args={"api_key": os.getenv("OPENAI_API_KEY", "")},
    model_id="gpt-4o",
)

# Create the Strands agent
strands_agent = Agent(
    model=model,
    system_prompt="Always communicate in the preferred language of the user as defined in your state. Do not communicate in any other language.",
)

# Inject state into the prompt
def language_prompt(input_data, user_message: str) -> str:
    state_dict = getattr(input_data, "state", None)
    if isinstance(state_dict, dict) and "language" in state_dict:
        return f"Current language: {state_dict['language']}\n\nUser request: {user_message}"
    return user_message

config = StrandsAgentConfig(state_context_builder=language_prompt)

# Wrap with AG-UI integration
agui_agent = StrandsAgent(
    agent=strands_agent,
    name="languageAgent",
    description="Always communicate in the preferred language of the user",
    config=config,
)

app = create_strands_app(agui_agent)

Use the `useAgent` Hook#

With your agent connected and running, call the useAgent hook, pass the agent's name, and use agent.setState to update the agent state.

ui/app/page.tsx


// Define the agent state type to match your Strands agent
type AgentState = {
language: "english" | "spanish";
};

function YourMainContent() {
  const { agent } = useAgent({
    agentId: "languageAgent",
    // optionally provide a type-safe initial state
    initialState: { language: "spanish" }
  });

  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>
  );
}

The agent.setState function in useAgent will update the agent state and trigger a rerender when the state changes.

Give it a try!#

You can now use the setState function to update the agent state and 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.

Important

Shared-state in AWS Strands is prompt-driven. This means that your Agent's awareness of the shared state will be augmented by the instructions you provide to your agent.