Copilot SDK - Quickstart (#59593)

Co-authored-by: Joe Clark <31087804+jc-clark@users.noreply.github.com>

Author: sunbrye

content/copilot/how-tos/copilot-sdk/index.md

@@ -0,0 +1,10 @@
+---
+title: GitHub Copilot SDK
+shortTitle: Copilot SDK
+intro: Learn how to customize your {% data variables.product.prodname_copilot_short %} experience using {% data variables.copilot.copilot_sdk_short %}.
+versions:
+  feature: copilot
+children:
+  - /sdk-getting-started
+contentType: how-tos
+---

content/copilot/how-tos/copilot-sdk/sdk-getting-started.md

@@ -0,0 +1,150 @@
+---
+title: Getting started with Copilot SDK
+shortTitle: Quickstart
+intro: 'Learn how to install {% data variables.copilot.copilot_sdk_short %} and send your first message.'
+allowTitleToDifferFromFilename: true
+product: '{% data reusables.gated-features.copilot-sdk %}' 
+versions:
+  feature: copilot
+topics:
+  - Copilot
+contentType: get-started
+category:
+  - Learn about Copilot
+  - Author and optimize with Copilot
+---
+
+> [!NOTE]
+>{% data variables.copilot.copilot_sdk_short %} is currently in {% data variables.release-phases.technical_preview %}. Functionality and availability are subject to change.
+
+{% 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](https://github.com/github/copilot-sdk/blob/main/docs/getting-started.md) in the `github/copilot-sdk` repository.
+
+## Prerequisites
+
+Before you begin, make sure you have **Node.js 18** or later installed.
+
+## Authentication
+
+Follow the instructions at [AUTOTITLE](/copilot/how-tos/copilot-cli/install-copilot-cli) 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:
+
+    ```bash copy
+    copilot --version
+    ```
+
+## Installation
+
+1. Create a new directory and initialize your project:
+
+    ```bash copy
+    mkdir copilot-demo && cd copilot-demo
+    npm init -y --init-type module
+    ```
+
+1. Install the SDK and TypeScript runner:
+
+    ```bash copy
+    npm install @github/copilot-sdk tsx
+    ```
+
+## Send your first message
+
+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.
+
+    ```typescript copy
+    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);
+    ```
+
+1. Run the code:
+
+    ```bash copy
+    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.
+
+## Add streaming responses
+
+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:
+
+    ```typescript copy
+    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);
+    ```
+
+1. Run the code:
+
+    ```bash copy
+    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.
+
+### Event subscription methods
+
+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:
+
+```typescript copy
+// 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();
+```
+
+## Next steps
+
+To continue getting started with {% data variables.copilot.copilot_sdk_short %}, see [Build Your First Copilot-Powered App](https://github.com/github/copilot-sdk/blob/main/docs/getting-started.md#step-4-add-a-custom-tool) in the `github/copilot-sdk` repository. 

content/copilot/how-tos/index.md

@@ -11,6 +11,7 @@ children:
   - /get-code-suggestions
   - /chat-with-copilot
   - /copilot-cli
+  - /copilot-sdk
   - /use-copilot-agents
   - /use-ai-models
   - /provide-context

data/reusables/gated-features/copilot-sdk.md

@@ -0,0 +1 @@
+{% data variables.copilot.copilot_sdk %} is available with all {% data variables.product.prodname_copilot_short %} plans.

data/variables/copilot.yml

@@ -82,6 +82,10 @@ copilot_custom_agent_caps_short: 'Custom agent'
 custom_agents_short: 'custom agents'
 custom_agents_caps_short: 'Custom agents'
 
+## Copilot SDK
+copilot_sdk: 'GitHub Copilot SDK'
+copilot_sdk_short: 'Copilot SDK'
+
 ## Copilot subagents
 subagent_short: 'subagent'
 subagent_caps_short: 'Subagent'