copilot-sdk skill

GitHub Copilot SDK

Build applications that programmatically interact with GitHub Copilot. The SDK wraps the Copilot CLI via JSON-RPC, providing session management, custom tools, hooks, MCP server integration, and streaming across Node.js, Python, Go, and .NET.

Prerequisites

• GitHub Copilot CLI installed and authenticated (copilot --version)
• GitHub Copilot subscription (Individual, Business, or Enterprise) — not required for BYOK
• Runtime: Node.js 18+ / Python 3.8+ / Go 1.21+ / .NET 8.0+

Installation

Language	Package	Install
Node.js	@github/copilot-sdk	npm install @github/copilot-sdk
Python	github-copilot-sdk	pip install github-copilot-sdk
Go	github.com/github/copilot-sdk/go	go get github.com/github/copilot-sdk/go
.NET	GitHub.Copilot.SDK	dotnet add package GitHub.Copilot.SDK

Architecture

The SDK communicates with the Copilot CLI via JSON-RPC over stdio (default) or TCP. The CLI manages model calls, tool execution, session state, and MCP server lifecycle.

Your App → SDK Client → [stdio/TCP] → Copilot CLI → Model Provider
                                          ↕
                                     MCP Servers

Transport modes:

Mode	Description	Use Case
Stdio (default)	CLI as subprocess via pipes	Local dev, single process
TCP	CLI as network server	Multi-client, backend services

---

Core Pattern: Client → Session → Message

All SDK usage follows: create a client, create a session, send messages.

Node.js / TypeScript

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();

Python

import asyncio
from copilot import CopilotClient

async def main():
    client = CopilotClient()
    await client.start()
    session = await client.create_session({"model": "gpt-4.1"})
    response = await session.send_and_wait({"prompt": "What is 2 + 2?"})
    print(response.data.content)
    await client.stop()

asyncio.run(main())

Go

client := copilot.NewClient(nil)
if err := client.Start(ctx); err != nil { log.Fatal(err) }
defer client.Stop()

session, _ := client.CreateSession(ctx, &copilot.SessionConfig{Model: "gpt-4.1"})
response, _ := session.SendAndWait(ctx, copilot.MessageOptions{Prompt: "What is 2 + 2?"})
fmt.Println(*response.Data.Content)

.NET

await using var client = new CopilotClient();
await using var session = await client.CreateSessionAsync(new SessionConfig { Model = "gpt-4.1" });
var response = await session.SendAndWaitAsync(new MessageOptions { Prompt = "What is 2 + 2?" });
Console.WriteLine(response?.Data.Content);

---

Streaming Responses

Enable real-time output by setting streaming: true and subscribing to delta events.

Node.js

const session = await client.createSession({ model: "gpt-4.1", streaming: true });

session.on("assistant.message_delta", (event) => {
    process.stdout.write(event.data.deltaContent);
});
session.on("session.idle", () => console.log());

await session.sendAndWait({ prompt: "Tell me a joke" });

Python

from copilot.generated.session_events import SessionEventType

session = await client.create_session({"model": "gpt-4.1", "streaming": True})

def handle_event(event):
    if event.type == SessionEventType.ASSISTANT_MESSAGE_DELTA:
        sys.stdout.write(event.data.delta_content)
        sys.stdout.flush()
    if event.type == SessionEventType.SESSION_IDLE:
        print()

session.on(handle_event)
await session.send_and_wait({"prompt": "Tell me a joke"})

Event Subscription

Method	Description
on(handler)	Subscribe to all events; returns unsubscribe function
on(eventType, handler)	Subscribe to specific event type (Node.js only)

Call the returned function to unsubscribe. In .NET, call .Dispose() on the returned disposable.

---

Custom Tools

Define tools that Copilot can call to extend its capabilities.

Node.js

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

const getWeather = defineTool("get_weather", {
    description: "Get the current weather for a city",
    parameters: {
        type: "object",
        properties: { city: { type: "string", description: "The city name" } },
        required: ["city"],
    },
    handler: async ({ city }) => ({ city, temperature: "72°F", condition: "sunny" }),
});

const session = await client.createSession({
    model: "gpt-4.1",
    tools: [getWeather],
});

Python

from copilot.tools import define_tool
from pydantic import BaseModel, Field

class GetWeatherParams(BaseModel):
    city: str = Field(description="The city name")

@define_tool(description="Get the current weather for a city")
async def get_weather(params: GetWeatherParams) -> dict:
    return {"city": params.city, "temperature": "72°F", "condition": "sunny"}

session = await client.create_session({"model": "gpt-4.1", "tools": [get_weather]})

Go

type WeatherParams struct {
    City string `json:"city" jsonschema:"The city name"`
}

getWeather := copilot.DefineTool("get_weather", "Get weather for a city",
    func(params WeatherParams, inv copilot.ToolInvocation) (WeatherResult, error) {
        return WeatherResult{City: params.City, Temperature: "72°F"}, nil
    },
)

session, _ := client.CreateSession(ctx, &copilot.SessionConfig{
    Model: "gpt-4.1",
    Tools: []copilot.Tool{getWeather},
})

.NET

using Microsoft.Extensions.AI;
using System.ComponentModel;

var getWeather = AIFunctionFactory.Create(
    ([Description("The city name")] string city) => new { city, temperature = "72°F" },
    "get_weather", "Get the current weather for a city");

await using var session = await client.CreateSessionAsync(new SessionConfig {
    Model = "gpt-4.1", Tools = [getWeather],
});

Tool Requirements

• Handler must return JSON-serializable data (not undefined)
• Parameters must follow JSON Schema format
• Tool description should clearly state when the tool should be used

---

Hooks

Intercept and customize session behavior at key lifecycle points.

Hook	Trigger	Use Case
onPreToolUse	Before tool executes	Permission control, argument modification
onPostToolUse	After tool executes	Result transformation, logging, redaction
onUserPromptSubmitted	User sends message	Prompt modification, filtering, context injection
onSessionStart	Session begins (new or resumed)	Add context, configure session
onSessionEnd	Session ends	Cleanup, analytics, metrics
onErrorOccurred	Error happens	Custom error handling, retry logic, monitoring

Pre-Tool Use Hook

Control tool permissions, modify arguments, or inject context before tool execution.

const session = await client.createSession({
    hooks: {
        onPreToolUse: async (input) => {
            if (["shell", "bash"].includes(input.toolName)) {
                return { permissionDecision: "deny", permissionDecisionReason: "Shell access not permitted" };
            }
            return { permissionDecision: "allow" };
        },
    },
});

Input fields: timestamp, cwd, toolName, toolArgs

Output fields:

Field	Type	Description
permissionDecision	"allow" | "deny" | "ask"	Whether to allow the tool call
permissionDecisionReason	string	Explanation for deny/ask
modifiedArgs	object	Modified arguments to pass
additionalContext	string	Extra context for conversation
suppressOutput	boolean	Hide tool output from conversation

Post-Tool Use Hook

Transform results, redact sensitive data, or log tool activity after execution.

hooks: {
    onPostToolUse: async (input) => {
        // Redact sensitive data from results
        if (typeof input.toolResult === "string") {
            let redacted = input.toolResult;
            for (const pattern of SENSITIVE_PATTERNS) {
                redacted = redacted.replace(pattern, "[REDACTED]");
            }
            if (redacted !== input.toolResult) {
                return { modifiedResult: redacted };
            }
        }
        return null; // Pass through unchanged
    },
}

Output fields: modifiedResult, additionalContext, suppressOutput

User Prompt Submitted Hook

Modify or enhance user prompts before processing. Useful for prompt templates, context injection, and input validation.

hooks: {
    onUserPromptSubmitted: async (input) => {
        return {
            modifiedPrompt: `[User from engineering team] ${input.prompt}`,
            additionalContext: "Follow company coding standards.",
        };
    },
}

Output fields: modifiedPrompt, additionalContext, suppressOutput

Session Lifecycle Hooks

hooks: {
    onSessionStart: async (input, invocation) => {
        // input.source: "startup" | "resume" | "new"
        console.log(`Session ${invocation.sessionId} started (${input.source})`);
        return { additionalContext: "Project uses TypeScript and React." };
    },
    onSessionEnd: async (input, invocation) => {
        // input.reason: "complete" | "error" | "abort" | "timeout" | "user_exit"
        await recordMetrics({ sessionId: invocation.sessionId, reason: input.reason });
        return null;
    },
}

Error Handling Hook

hooks: {
    onErrorOccurred: async (input) => {
        // input.errorContext: "model_call" | "tool_execution" | "system" | "user_input"
        // input.recoverable: boolean
        if (input.errorContext === "model_call" && input.error.includes("rate")) {
            return { errorHandling: "retry", retryCount: 3, userNotification: "Rate limited. Retrying..." };
        }
        return null; // Default error handling
    },
}

Output fields: suppressOutput, errorHandling ("retry" | "skip" | "abort"), retryCount, userNotification

Python Hook Example

async def on_pre_tool_use(input_data, invocation):
    if input_data["toolName"] in ["shell", "bash"]:
        return {"permissionDecision": "deny", "permissionDecisionReason": "Not permitted"}
    return {"permissionDecision": "allow"}

session = await client.create_session({
    "hooks": {"on_pre_tool_use": on_pre_tool_use}
})

Go Hook Example

session, _ := client.CreateSession(ctx, &copilot.SessionConfig{
    Hooks: &copilot.SessionHooks{
        OnPreToolUse: func(input copilot.PreToolUseHookInput, inv copilot.HookInvocation) (*copilot.PreToolUseHookOutput, error) {
            return &copilot.PreToolUseHookOutput{PermissionDecision: "allow"}, nil
        },
    },
})

---

MCP Server Integration

Connect to MCP (Model Context Protocol) servers for pre-built tool capabilities.

Local Stdio Server

const session = await client.createSession({
    mcpServers: {
        filesystem: {
            type: "local",
            command: "npx",
            args: ["-y", "@modelcontextprotocol/server-filesystem", "/allowed/path"],
            tools: ["*"],
            env: { DEBUG: "true" },
            cwd: "./servers",
            timeout: 30000,
        },
    },
});

Remote HTTP Server

const session = await client.createSession({
    mcpServers: {
        github: {
            type: "http",
            url: "https://api.githubcopilot.com/mcp/",
            headers: { Authorization: "Bearer ${TOKEN}" },
            tools: ["*"],
        },
    },
});

MCP Config Fields

Local/Stdio:

Field	Type	Required	Description
type	"local"	No	Defaults to local
command	string	Yes	Executable path
args	string[]	Yes	Command arguments
env	object	No	Environment variables
cwd	string	No	Working directory
tools	string[]	No	["*"] for all, [] for none
timeout	number	No	Timeout in milliseconds

Remote HTTP:

Field	Type	Required	Description
type	"http"	Yes	Server type
url	string	Yes	Server URL
headers	object	No	HTTP headers
tools	string[]	No	Tool filter
timeout	number	No	Timeout in ms

MCP Debugging

Test MCP servers independently before integrating:

echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}' | /path/to/your/mcp-server

Use the MCP Inspector for interactive debugging:

npx @modelcontextprotocol/inspector /path/to/your/mcp-server

Common MCP issues:

• Tools not appearing → Set tools: ["*"] and verify server responds to tools/list
• Server not starting → Use absolute command paths, check cwd
• Stdout pollution → Debug output must go to stderr, not stdout

---

Authentication

Methods (Priority Order)

1. Explicit token — githubToken in constructor
2. HMAC key — CAPI_HMAC_KEY or COPILOT_HMAC_KEY env vars
3. Direct API token — GITHUB_COPILOT_API_TOKEN with COPILOT_API_URL
4. Environment variables — COPILOT_GITHUB_TOKEN → GH_TOKEN → GITHUB_TOKEN
5. Stored OAuth — From copilot auth login
6. GitHub CLI — gh auth credentials

Programmatic Token

const client = new CopilotClient({ githubToken: process.env.GITHUB_TOKEN });

OAuth GitHub App

For multi-user apps where users sign in with GitHub:

const client = new CopilotClient({
    githubToken: userAccessToken,    // gho_ or ghu_ token from OAuth flow
    useLoggedInUser: false,          // Don't use stored CLI credentials
});

Supported token types: gho_ (OAuth), ghu_ (GitHub App), github_pat_ (fine-grained PAT). Not supported: ghp_ (classic PAT — deprecated).

Disable Auto-Login

Prevent the SDK from using stored credentials:

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

---

BYOK (Bring Your Own Key)

Use your own API keys — no Copilot subscription required. The CLI acts as agent runtime only.

Provider Configurations

OpenAI:

provider: { type: "openai", baseUrl: "https://api.openai.com/v1", apiKey: process.env.OPENAI_API_KEY }

Azure AI Foundry (OpenAI-compatible):

provider: {
    type: "openai",
    baseUrl: "https://your-resource.openai.azure.com/openai/v1/",
    apiKey: process.env.FOUNDRY_API_KEY,
    wireApi: "responses",  // Use "responses" for GPT-5 series, "completions" for others
}

Azure OpenAI (native endpoint):

provider: {
    type: "azure",
    baseUrl: "https://my-resource.openai.azure.com",  // Just the host — no /openai/v1
    apiKey: process.env.AZURE_OPENAI_KEY,
    azure: { apiVersion: "2024-10-21" },
}

Anthropic:

provider: { type: "anthropic", baseUrl: "https://api.anthropic.com", apiKey: process.env.ANTHROPIC_API_KEY }

Ollama (local):

provider: { type: "openai", baseUrl: "http://localhost:11434/v1" }

Provider Config Reference

Field	Type	Description
type	"openai" | "azure" | "anthropic"	Provider type
baseUrl	string	Required. API endpoint URL
apiKey	string	API key (optional for local providers)
bearerToken	string	Bearer token auth (takes precedence over apiKey)
wireApi	"completions" | "responses"	API format (default: "completions")
azure.apiVersion	string	Azure API version (default: "2024-10-21")

Azure Managed Identity with BYOK

Use DefaultAzureCredential to get short-lived bearer tokens for Azure deployments:

from azure.identity import DefaultAzureCredential
from copilot import CopilotClient, ProviderConfig, SessionConfig

credential = DefaultAzureCredential()
token = credential.get_token("https://cognitiveservices.azure.com/.default").token

session = await client.create_session(SessionConfig(
    model="gpt-4.1",
    provider=ProviderConfig(
        type="openai",
        base_url=f"{foundry_url}/openai/v1/",
        bearer_token=token,
        wire_api="responses",
    ),
))

Note: Bearer tokens expire (~1 hour). For long-running apps, refresh the token before each new session. The SDK does not auto-refresh tokens.

BYOK Limitations

• Static credentials only — no native Entra ID, OIDC, or managed identity support
• No auto-refresh — expired tokens require creating a new session
• Keys not persisted — must re-provide provider config on session resume
• Model availability — limited to what your provider offers

---

Session Persistence

Resume sessions across restarts by providing your own session ID.

// Create with explicit ID
const session = await client.createSession({
    sessionId: "user-123-task-456",
    model: "gpt-4.1",
});

// Resume later (even from a different client instance)
const resumed = await client.resumeSession("user-123-task-456");
await resumed.sendAndWait({ prompt: "What did we discuss?" });

Session Management

const sessions = await client.listSessions();           // List all
const lastId = await client.getLastSessionId();          // Get most recent
await client.deleteSession("user-123-task-456");         // Delete from storage
await session.destroy();                                 // Destroy active session

Resume Options

When resuming, you can reconfigure: model, systemMessage, availableTools, excludedTools, provider (required for BYOK), reasoningEffort, streaming, mcpServers, customAgents, skillDirectories, infiniteSessions.

Session ID Best Practices

Pattern	Example	Use Case
user-{userId}-{taskId}	user-alice-pr-review-42	Multi-user apps
tenant-{tenantId}-{workflow}	tenant-acme-onboarding	Multi-tenant SaaS
{userId}-{taskType}-{timestamp}	alice-deploy-1706932800	Time-based cleanup

What Gets Persisted

Session state is saved to ~/.copilot/session-state/{sessionId}/:

Data	Persisted?	Notes
Conversation history	✅ Yes	Full message thread
Tool call results	✅ Yes	Cached for context
Agent planning state	✅ Yes	plan.md file
Session artifacts	✅ Yes	In files/ directory
Provider/API keys	❌ No	Must re-provide on resume
In-memory tool state	❌ No	Design tools to be stateless

Infinite Sessions

For long-running workflows that may exceed context limits, enable auto-compaction:

const session = await client.createSession({
    infiniteSessions: {
        enabled: true,
        backgroundCompactionThreshold: 0.80,  // Start background compaction at 80%
        bufferExhaustionThreshold: 0.95,       // Block and compact at 95%
    },
});

Thresholds are context utilization ratios (0.0–1.0), not absolute token counts.

---

Custom Agents

Define specialized AI personas:

const session = await client.createSession({
    customAgents: [{
        name: "pr-reviewer",
        displayName: "PR Reviewer",
        description: "Reviews pull requests for best practices",
        prompt: "You are an expert code reviewer. Focus on security, performance, and maintainability.",
    }],
});

---

System Message

Control AI behavior and personality:

const session = await client.createSession({
    systemMessage: { content: "You are a helpful assistant. Always be concise." },
});

---

Skills Integration

Load skill directories to extend Copilot's capabilities:

const session = await client.createSession({
    skillDirectories: ["./skills/code-review", "./skills/documentation"],
    disabledSkills: ["experimental-feature"],
});

Skills can be combined with custom agents and MCP servers:

const session = await client.createSession({
    skillDirectories: ["./skills/security"],
    customAgents: [{ name: "auditor", prompt: "Focus on OWASP Top 10." }],
    mcpServers: { postgres: { type: "local", command: "npx", args: ["-y", "@modelcontextprotocol/server-postgres"], tools: ["*"] } },
});

---

Permission & Input Handlers

Handle tool permissions and user input requests programmatically. The SDK uses a deny-by-default permission model — all permission requests are denied unless you provide a handler.

const session = await client.createSession({
    onPermissionRequest: async (request) => {
        if (request.kind === "shell") {
            return { approved: request.command.startsWith("git") };
        }
        return { approved: true };
    },
    onUserInputRequest: async (request) => {
        return { response: "yes" };
    },
});

Token Usage Tracking

Subscribe to usage events instead of using CLI /usage:

session.on("assistant.usage", (event) => {
    console.log("Tokens:", { input: event.data.inputTokens, output: event.data.outputTokens });
});

---

Deployment Patterns

Local CLI (Default)

SDK auto-spawns CLI as subprocess. Simplest setup — zero configuration.

const client = new CopilotClient(); // Auto-manages CLI process

External CLI Server (Backend Services)

Run CLI in headless mode, connect SDK over TCP:

copilot --headless --port 4321

const client = new CopilotClient({ cliUrl: "localhost:4321" });

Multi-client support: Multiple SDK clients can share one CLI server.

Bundled CLI (Desktop Apps)

Ship CLI binary with your app:

const client = new CopilotClient({ cliPath: path.join(__dirname, "vendor", "copilot") });

Docker Compose

services:
  copilot-cli:
    image: ghcr.io/github/copilot-cli:latest
    command: ["--headless", "--port", "4321"]
    environment:
      - COPILOT_GITHUB_TOKEN=${COPILOT_GITHUB_TOKEN}
    volumes:
      - session-data:/root/.copilot/session-state
  api:
    build: .
    environment:
      - CLI_URL=copilot-cli:4321
    depends_on: [copilot-cli]
volumes:
  session-data:

Session Isolation Patterns

Pattern	Isolation	Resources	Best For
CLI per user	Complete	High	Multi-tenant SaaS, compliance
Shared CLI + session IDs	Logical	Low	Internal tools
Shared sessions	None	Low	Team collaboration (requires locking)

Production Checklist

• Session cleanup: periodic deletion of expired sessions
• Health checks: ping CLI server, restart if unresponsive
• Persistent storage: mount ~/.copilot/session-state/ for containers
• Secret management: use Vault/K8s Secrets for tokens
• Session locking: Redis or similar for shared session access
• Graceful shutdown: drain active sessions before stopping CLI

---