Copilot SDK for Node.js/TypeScript

TypeScript SDK for programmatic control of GitHub Copilot CLI via JSON-RPC.

Note: This SDK is in technical preview and may change in breaking ways.

Installation

npm install @github/copilot-sdk

Quick Start

import { CopilotClient } from "@github/copilot-sdk";

// Create and start client
const client = new CopilotClient();
await client.start();

// Create a session
const session = await client.createSession({
    model: "gpt-5",
});

// Wait for response using session.idle event
const done = new Promise<void>((resolve) => {
    session.on((event) => {
        if (event.type === "assistant.message") {
            console.log(event.data.content);
        } else if (event.type === "session.idle") {
            resolve();
        }
    });
});

// Send a message and wait for completion
await session.send({ prompt: "What is 2+2?" });
await done;

// Clean up
await session.destroy();
await client.stop();

API Reference

CopilotClient

Constructor

new CopilotClient(options?: CopilotClientOptions)

Options:

• cliPath?: string - Path to CLI executable (default: "copilot" from PATH)
• cliArgs?: string[] - Extra arguments prepended before SDK-managed flags (e.g. ["./dist-cli/index.js"] when using node)
• cliUrl?: string - URL of existing CLI server to connect to (e.g., "localhost:8080", "http://127.0.0.1:9000", or just "8080"). When provided, the client will not spawn a CLI process.
• port?: number - Server port (default: 0 for random)
• useStdio?: boolean - Use stdio transport instead of TCP (default: true)
• logLevel?: string - Log level (default: "info")
• autoStart?: boolean - Auto-start server (default: true)
• autoRestart?: boolean - Auto-restart on crash (default: true)

Methods

start(): Promise<void>

Start the CLI server and establish connection.

stop(): Promise<Error[]>

Stop the server and close all sessions. Returns a list of any errors encountered during cleanup.

forceStop(): Promise<void>

Force stop the CLI server without graceful cleanup. Use when stop() takes too long.

createSession(config?: SessionConfig): Promise<CopilotSession>

Create a new conversation session.

Config:

• sessionId?: string - Custom session ID
• model?: string - Model to use ("gpt-5", "claude-sonnet-4.5", etc.)
• tools?: Tool[] - Custom tools exposed to the CLI
• systemMessage?: SystemMessageConfig - System message customization (see below)

resumeSession(sessionId: string, config?: ResumeSessionConfig): Promise<CopilotSession>

Resume an existing session.

ping(message?: string): Promise<{ message: string; timestamp: number }>

Ping the server to check connectivity.

getState(): ConnectionState

Get current connection state.

listSessions(): Promise<SessionMetadata[]>

List all available sessions.

deleteSession(sessionId: string): Promise<void>

Delete a session and its data from disk.

---

CopilotSession

Represents a single conversation session.

Methods

send(options: MessageOptions): Promise<string>

Send a message to the session. Returns immediately after the message is queued; use event handlers or sendAndWait() to wait for completion.

Options:

• prompt: string - The message/prompt to send
• attachments?: Array<{type, path, displayName}> - File attachments
• mode?: "enqueue" | "immediate" - Delivery mode

Returns the message ID.

sendAndWait(options: MessageOptions, timeout?: number): Promise<AssistantMessageEvent | undefined>

Send a message and wait until the session becomes idle.

Options:

• prompt: string - The message/prompt to send
• attachments?: Array<{type, path, displayName}> - File attachments
• mode?: "enqueue" | "immediate" - Delivery mode
• timeout?: number - Optional timeout in milliseconds

Returns the final assistant message event, or undefined if none was received.

on(handler: SessionEventHandler): () => void

Subscribe to session events. Returns an unsubscribe function.

const unsubscribe = session.on((event) => {
    console.log(event);
});

// Later...
unsubscribe();

abort(): Promise<void>

Abort the currently processing message in this session.

getMessages(): Promise<SessionEvent[]>

Get all events/messages from this session.

destroy(): Promise<void>

Destroy the session and free resources.

---

Event Types

Sessions emit various events during processing:

• user.message - User message added
• assistant.message - Assistant response
• assistant.message_delta - Streaming response chunk
• tool.execution_start - Tool execution started
• tool.execution_end - Tool execution completed
• And more...

See SessionEvent type in the source for full details.

Streaming

Enable streaming to receive assistant response chunks as they're generated:

const session = await client.createSession({
    model: "gpt-5",
    streaming: true,
});

// Wait for completion using session.idle event
const done = new Promise<void>((resolve) => {
    session.on((event) => {
        if (event.type === "assistant.message_delta") {
            // Streaming message chunk - print incrementally
            process.stdout.write(event.data.deltaContent);
        } else if (event.type === "assistant.reasoning_delta") {
            // Streaming reasoning chunk (if model supports reasoning)
            process.stdout.write(event.data.deltaContent);
        } else if (event.type === "assistant.message") {
            // Final message - complete content
            console.log("\n--- Final message ---");
            console.log(event.data.content);
        } else if (event.type === "assistant.reasoning") {
            // Final reasoning content (if model supports reasoning)
            console.log("--- Reasoning ---");
            console.log(event.data.content);
        } else if (event.type === "session.idle") {
            // Session finished processing
            resolve();
        }
    });
});

await session.send({ prompt: "Tell me a short story" });
await done; // Wait for streaming to complete

When streaming: true:

• assistant.message_delta events are sent with deltaContent containing incremental text
• assistant.reasoning_delta events are sent with deltaContent for reasoning/chain-of-thought (model-dependent)
• Accumulate deltaContent values to build the full response progressively
• The final assistant.message and assistant.reasoning events contain the complete content

Note: assistant.message and assistant.reasoning (final events) are always sent regardless of streaming setting.

Advanced Usage

Manual Server Control

const client = new CopilotClient({ autoStart: false });

// Start manually
await client.start();

// Use client...

// Stop manually
await client.stop();

Tools

You can let the CLI call back into your process when the model needs capabilities you own. Use defineTool with Zod schemas for type-safe tool definitions:

import { z } from "zod";
import { CopilotClient, defineTool } from "@github/copilot-sdk";

const session = await client.createSession({
    model: "gpt-5",
    tools: [
        defineTool("lookup_issue", {
            description: "Fetch issue details from our tracker",
            parameters: z.object({
                id: z.string().describe("Issue identifier"),
            }),
            handler: async ({ id }) => {
                const issue = await fetchIssue(id);
                return issue;
            },
        }),
    ],
});

When Copilot invokes lookup_issue, the client automatically runs your handler and responds to the CLI. Handlers can return any JSON-serializable value (automatically wrapped), a simple string, or a ToolResultObject for full control over result metadata. Raw JSON schemas are also supported if Zod isn't desired.

System Message Customization

Control the system prompt using systemMessage in session config:

const session = await client.createSession({
    model: "gpt-5",
    systemMessage: {
        content: `
<workflow_rules>
- Always check for security vulnerabilities
- Suggest performance improvements when applicable
</workflow_rules>
`,
    },
});

The SDK auto-injects environment context, tool instructions, and security guardrails. The default CLI persona is preserved, and your content is appended after SDK-managed sections. To change the persona or fully redefine the prompt, use mode: "replace".

For full control (removes all guardrails), use mode: "replace":

const session = await client.createSession({
    model: "gpt-5",
    systemMessage: {
        mode: "replace",
        content: "You are a helpful assistant.",
    },
});

Multiple Sessions

const session1 = await client.createSession({ model: "gpt-5" });
const session2 = await client.createSession({ model: "claude-sonnet-4.5" });

// Both sessions are independent
await session1.sendAndWait({ prompt: "Hello from session 1" });
await session2.sendAndWait({ prompt: "Hello from session 2" });

Custom Session IDs

const session = await client.createSession({
    sessionId: "my-custom-session-id",
    model: "gpt-5",
});

File Attachments

await session.send({
    prompt: "Analyze this file",
    attachments: [
        {
            type: "file",
            path: "/path/to/file.js",
            displayName: "My File",
        },
    ],
});

Error Handling

try {
    const session = await client.createSession();
    await session.send({ prompt: "Hello" });
} catch (error) {
    console.error("Error:", error.message);
}

Requirements

• Node.js >= 18.0.0
• GitHub Copilot CLI installed and in PATH (or provide custom cliPath)

License

MIT