{% data reusables.copilot.copilot-sdk.technical-preview-note %}

{% data variables.copilot.copilot_sdk %} lets you build applications powered by {% data variables.product.prodname_copilot %} in your preferred programming language. In this guide, you'll install the SDK using npm, send your first message, and add streaming responses.

For more information and steps for other languages, see Install the SDK in the github/copilot-sdk repository.

Before you begin, make sure you have Node.js 18 or later installed.

Follow the instructions at AUTOTITLE to install and authenticate with {% data variables.copilot.copilot_cli %}. This will allow the SDK to access your {% data variables.product.github %} account and use {% data variables.product.prodname_copilot_short %}.

1. Verify that {% data variables.copilot.copilot_cli_short %} is installed and working:

   copilot --version

1. Create a new directory and initialize your project:

   mkdir copilot-demo && cd copilot-demo
   npm init -y --init-type module

2. Install the SDK and TypeScript runner:

   npm install @github/copilot-sdk tsx

1. Create a new file index.ts and add the following code. This sends a single prompt to {% data variables.product.prodname_copilot_short %} and prints the response.

   import { CopilotClient } from "@github/copilot-sdk";
   
   const client = new CopilotClient();
   const session = await client.createSession({ model: "gpt-4.1" });
   
   const response = await session.sendAndWait({ prompt: "What is 2 + 2?" });
   console.log(response?.data.content);
   
   await client.stop();
   process.exit(0);

2. Run the code:

   npx tsx index.ts

In this example:

• CopilotClient() creates a new client that manages the connection to {% data variables.copilot.copilot_cli_short %}.
• createSession() starts a new conversation session with the specified model.
• sendAndWait() sends a prompt and waits for the complete response before returning.

Instead of waiting for the full response, you can stream it as it's generated. This is useful for long responses or interactive applications where you want to display output in real time.

1. Update index.ts with the following code to listen and print response chunks as they arrive:

   import { CopilotClient } from "@github/copilot-sdk";
   
   const client = new CopilotClient();
   const session = await client.createSession({
       model: "gpt-4.1",
       streaming: true,
   });
   
   // Listen for response chunks
   session.on("assistant.message_delta", (event) => {
       process.stdout.write(event.data.deltaContent);
   });
   session.on("session.idle", () => {
       console.log(); // New line when done
   });
   
   await session.sendAndWait({ prompt: "Tell me a short joke" });
   
   await client.stop();
   process.exit(0);

2. Run the code:

   npx tsx index.ts

With streaming enabled, the response appears incrementally as it's generated. You can subscribe to events to process each chunk in real time:

• assistant.message_delta fires for each chunk of the response as it's generated.
• session.idle fires when the response is complete and the session is ready for the next message.

The SDK provides the following methods to subscribe to events:

• on(handler): Subscribe to all events. Returns the unsubscribe function.
• on(eventType, handler): Subscribe to a specific event type. Returns the unsubscribe function.

Add the following code to index.ts to subscribe to events and unsubscribe when you no longer need them:

// Subscribe to all events
const unsubscribeAll = session.on((event) => {
    console.log("Event:", event.type);
});

// Subscribe to specific event type
const unsubscribeIdle = session.on("session.idle", (event) => {
    console.log("Session is idle");
});

// Later, to unsubscribe:
unsubscribeAll();
unsubscribeIdle();

To continue getting started with {% data variables.copilot.copilot_sdk_short %}, see Build Your First Copilot-Powered App in the github/copilot-sdk repository.