SKILL.md

GitHub Copilot SDK

Overview

The GitHub Copilot SDK exposes the same Copilot CLI agent runtime over JSON-RPC, so apps can drive Copilot programmatically instead of building their own orchestration layer.

Status: Public preview

SDKs: Node.js/TypeScript, Python, Go, .NET, Java

Architecture: Application -> SDK client -> JSON-RPC -> Copilot CLI

How to use this skill

When helping with the Copilot SDK:

Prefer the official docs index and the language-specific README over memory.

Treat the top-level SDK README plus docs/ as the source of truth for shared behavior.

Call out preview status when stability or breaking changes matter.

Avoid hardcoding model lists when runtime discovery via listModels() is available.

Watch for stale guidance around permissions, lifecycle methods, and event names.

Current source of truth

High-value facts

Authentication and prerequisites

A GitHub Copilot subscription is required for normal SDK use.

BYOK is supported and does not require GitHub Copilot authentication.

Node.js, Python, and .NET bundle the Copilot CLI automatically.

Go can use an installed CLI or embed/bundle one with the go tool bundler workflow.

Java currently lives in github/copilot-sdk-java and expects the CLI to be installed separately.

Azure Managed Identity / Entra auth is supported as a documented BYOK pattern by passing short-lived bearer tokens from DefaultAzureCredential.

Permissions

The SDK uses a deny-by-default permission model.

In practice, create/resume flows should provide an explicit permission handler such as:

TypeScript: approveAll

Python: PermissionHandler.approve_all

Go: copilot.PermissionHandler.ApproveAll

.NET: PermissionHandler.ApproveAll

Java: PermissionHandler.APPROVE_ALL

Session lifecycle

Preferred cleanup method: disconnect()

Deprecated cleanup method: destroy()

To resume sessions reliably, provide your own sessionId when creating them.

BYOK provider configuration must be provided again when resuming because keys are not persisted.

Transport and deployment

Default transport is stdio with an SDK-managed CLI process.

You can connect to an external headless CLI server via cliUrl.

Current external server docs use:

copilot --headless --port 4321

Models

Do not hardcode model support unless the user specifically needs a fixed list.

Prefer client.listModels() and the official supported-models page.

reasoningEffort exists for models that support it.

Installation

SDK

Install

Node.js / TypeScript

npm install @github/copilot-sdk

Python

pip install github-copilot-sdk

go get github.com/github/copilot-sdk/go

.NET

dotnet add package GitHub.Copilot.SDK

Java

Maven/Gradle package com.github:copilot-sdk-java

Setup and deployment choices

Pick the setup that matches the application shape:

Local CLI - simplest path for personal tools and development.

Bundled CLI - ship a CLI binary with your app for desktop/distributable tooling.

Backend services - run the CLI in headless mode and connect with cliUrl.

Scaling and multi-tenancy - shared CLI vs CLI-per-user, shared storage, and session locking.

Azure Managed Identity - use BYOK with short-lived bearer tokens instead of static API keys when Azure auth is the real requirement.

Quick start pattern

Use the same mental model in every language:

Create/start the client.

Create a session with a permission handler.

Send with send() or sendAndWait().

Wait for session.idle or the returned final message.

disconnect() the session and stop/dispose the client.

TypeScript example

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

const client = new CopilotClient();

await client.start();

const session = await client.createSession({

  model: "gpt-5",

  streaming: true,

  onPermissionRequest: approveAll,

});

session.on("assistant.message_delta", (event) => {

  process.stdout.write(event.data.deltaContent ?? "");

});

await session.sendAndWait({ prompt: "What is 2+2?" });

await session.disconnect();

await client.stop();

Core capabilities to remember

Client and session APIs

Common operations across SDKs:

Client lifecycle: start(), stop(), forceStop()

Session lifecycle: createSession(), resumeSession(), disconnect()

Messaging: send(), sendAndWait(), abort(), getMessages()

Discovery: listModels(), listSessions(), getStatus() / ping()

Events and streaming

Final assistant output arrives in assistant.message.

Streaming text arrives in assistant.message_delta.

session.idle is the reliable "turn complete" signal.

The event system now includes reasoning, tool progress, permission, elicitation, sub-agent, and skill events.

See references/event-system.md.

Custom tools

Node uses defineTool(...) with Zod or raw JSON Schema.

Python uses @define_tool with Pydantic models.

Go prefers DefineTool(...).

.NET uses AIFunctionFactory.Create(...).

Overriding built-ins always requires explicit opt-in:

TypeScript: overridesBuiltInTool: true

Python: overrides_built_in_tool=True

Go: OverridesBuiltInTool = true

.NET: AdditionalProperties["is_override"] = true

Custom tools can also opt into skipPermission.

Custom agents, MCP, hooks, and skills

customAgents lets you define sub-agents per session.

mcpServers attaches local or remote MCP servers.

Hooks provide control points such as onPreToolUse, onPostToolUse, onUserPromptSubmitted, and lifecycle/error hooks.

Skills are loaded with skillDirectories; disable selectively with disabledSkills.

See references/cli-agents-mcp.md.

Attachments, commands, and interaction

Sessions can send file, directory, and image attachments.

Image input supports both file and blob attachments, and vision should be checked through model capabilities.

In-flight messaging supports mode: "immediate" for steering and mode: "enqueue" for queueing.

The SDK can register custom slash commands.

Apps can answer user questions with onUserInputRequest.

Rich UI prompts are available through elicitation handlers and session.ui when the connected client supports them.

Telemetry and observability

The SDK supports OpenTelemetry configuration through TelemetryConfig.

Trace context propagation is built in, with Node using an explicit onGetTraceContext callback for outbound propagation.

Persistence and long-running work

Use a stable sessionId for resumable sessions.

Use infiniteSessions for long-running workflows that may need compaction.

Session state is stored under ~/.copilot/session-state/ unless configuration overrides it.

SDK vs. CLI-only features

The SDK exposes programmatic surfaces for sessions, models, plans, mode switching, workspace files, custom agents, hooks, MCP, skills, and telemetry.

Many terminal UX features remain CLI-only, such as most slash-command workflows, interactive pickers, and export/share commands.

When translating a CLI workflow into app code, check the compatibility guide before assuming a slash command has an SDK equivalent.

Language conventions

Concept

TypeScript

Python

.NET

Java

Create session

createSession()

create_session()

CreateSession()

CreateSessionAsync()

createSession()

Resume session

resumeSession()

resume_session()

ResumeSession()

ResumeSessionAsync()

resumeSession()

Final content

event.data.content

*event.Data.Content

evt.Data.Content

event.getData().content()

Delta content

event.data.deltaContent

event.data.delta_content

*event.Data.DeltaContent

evt.Data.DeltaContent

event.getData().deltaContent()

Skills field

skillDirectories

skill_directories

SkillDirectories

setSkillDirectories(...)

Common gotchas

The SDK is public preview, so older examples drift quickly.

Hardcoded model tables get stale; prefer runtime discovery.

destroy() still appears in older examples but disconnect() is the current method.

A missing permission handler causes confusion fast; treat it as required for real sessions.

assistant.message and assistant.message_delta use event.data.*, not top-level event.content.

Streaming/event subscriptions should be attached before send().

Session resumption without a caller-provided sessionId is awkward to operationalize.

Local reference files in this skill

references/working-examples.md - current starter examples, including tools and resume patterns

references/event-system.md - event names, lifecycle, and language access patterns

references/cli-agents-mcp.md - custom agents, skills, MCP, headless CLI, and config locations

references/troubleshooting.md - common failures, debug logging, auth, permissions, and transport issues

copilot-sdk