Building and Using the Java SDK for Copilot
Using AI Agents

What We'll Cover

Whether you want to extend Copilot or rethink how you ship software with AI, this talk has something for you.

GitHub Copilot Is More Than an Editor Plugin

The Copilot CLI exposes a JSON-RPC API over stdio.

The SDK wraps that API with idiomatic Java — sessions, events, tools.

Copilot SDK for Java

<dependency>
  <groupId>com.github</groupId>
  <artifactId>copilot-sdk-java</artifactId>
  <version>0.1.32-java.0</version>
</dependency>

Architecture

The CLI handles auth, protocol, model routing. Your app just sends messages and handles events.

Hello, Copilot! DEMO

// Works with JBang — no project setup needed!
// //DEPS com.github:copilot-sdk-java:0.1.32-java.0

import com.github.copilot.sdk.*;
import com.github.copilot.sdk.events.*;
import com.github.copilot.sdk.json.*;

try (var client = new CopilotClient()) {
    client.start().get();                                          // spawn Copilot CLI

    var session = client.createSession(
        new SessionConfig()
            .setOnPermissionRequest(PermissionHandler.APPROVE_ALL)
            .setModel("claude-sonnet-4.5")
    ).get();

    var response = session.sendAndWait(
        new MessageOptions().setPrompt("What is 2 + 2?")
    ).get();

    System.out.println(response.getData().content());             // 4
}

Streaming Responses & Events

var done = new CompletableFuture<Void>();

// Print each word as it arrives
session.on(AssistantMessageDeltaEvent.class, delta -> {
    System.out.print(delta.getData().deltaContent());     // streaming chunk
});

// Know exactly when the model is done
session.on(SessionIdleEvent.class, idle -> {
    System.out.println();
    done.complete(null);
});

// Track token consumption
session.on(SessionUsageInfoEvent.class, usage -> {
    var d = usage.getData();
    System.out.printf("Tokens: %d / %d%n",
        (int) d.currentTokens(), (int) d.tokenLimit());
});

session.send(new MessageOptions().setPrompt("Tell me a haiku about Java")).get();
done.get();

Custom Tools DEMO

// Give Copilot the ability to call your code
var weatherTool = ToolDefinition.create(
    "get_weather",
    "Return current weather for a city",
    Map.of(
        "type", "object",
        "properties", Map.of(
            "city", Map.of("type", "string", "description", "City name")
        ),
        "required", List.of("city")
    ),
    invocation -> {
        String city = (String) invocation.getArguments().get("city");
        String weather = MyWeatherService.fetch(city);   // your logic
        return CompletableFuture.completedFuture(
            new ToolResult().setContent(weather)
        );
    }
);

var session = client.createSession(
    new SessionConfig()
        .setOnPermissionRequest(PermissionHandler.APPROVE_ALL)
        .setTools(List.of(weatherTool))
).get();

MCP Servers — Plug in External Tools

// Give Copilot access to your filesystem
Map<String, Object> fsServer = Map.of(
    "type",    "local",
    "command", "npx",
    "args",    List.of(
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/tmp"
    ),
    "tools",   List.of("*")
);

var session = client.createSession(
    new SessionConfig()
        .setOnPermissionRequest(
            PermissionHandler.APPROVE_ALL)
        .setMcpServers(Map.of("fs", fsServer))
).get();

Map.of(
  "type", "http",
  "url",  "https://api.example.com/mcp",
  "headers", Map.of(
    "Authorization", "Bearer " + token),
  "tools", List.of("*")
)

More Session Features

// Save
String id = session.getSessionId();

// Later…
var s2 = client.resumeSession(
  new ResumeSessionConfig()
    .setSessionId(id)
    .setOnPermissionRequest(...)
).get();

// Run sessions concurrently
var coder = client.createSession(
    new SessionConfig()
      .setModel("gpt-5")).get();

var reviewer = client.createSession(
    new SessionConfig()
      .setModel("claude-sonnet-4.5")
).get();

// Summarise history to
// stay within token limit
session.compact().get();

// Hot-swap model mid-chat
session.setModel("o3").get();

Security: Permission Hooks

// Every createSession / resumeSession MUST provide a permission handler
var session = client.createSession(
    new SessionConfig()
        .setOnPermissionRequest((request, invocation) -> {
            // request.getPermissionKind() — what is being asked
            // invocation.getToolName()    — which tool wants permission
            // invocation.getArguments()  — what arguments it will use

            if (request.getPermissionKind().equals("write_file")) {
                boolean ok = promptUser("Allow writing to " + invocation.getArguments().get("path") + "?");
                return CompletableFuture.completedFuture(
                    new PermissionRequestResult().setKind(ok ? "allow" : "deny")
                );
            }

            // Approve everything else (convenient for development)
            return CompletableFuture.completedFuture(
                new PermissionRequestResult().setKind("allow")
            );
        })
).get();

Real-World Usage: JMeter Copilot Plugin

🤖 Building the SDK with AI Agents

How we used GitHub Copilot's own agentic capabilities
to build and maintain the SDK

Agentic Upstream Sync AI

a3f91cb

Documentation Coverage Assessment AI

A reusable prompt asks the agent to audit documentation against the public API.

PR Automation — End to End AI

Every pull request in this repo follows an agentic workflow:

The agent uses the SDK it is maintaining to orchestrate its own merge workflows — meta AI engineering.

Skills = Reusable Prompts

Lessons Learned

🧪 Hands-On Lab

Build a Copilot-powered CLI in 15 minutes with JBang — no project setup needed.

jbang init MyCopilot.java
# add //DEPS header
# run with: jbang MyCopilot.java

mvn archetype:generate \
  -DarchetypeArtifactId=\
    maven-archetype-plugin
# add SDK dependency
# run: mvn copilot:review

Lab instructions → docs/javaone/lab.md in the repository

Resources

# Run the example directly from GitHub
jbang https://github.com/github/copilot-sdk-java/blob/latest/jbang-example.java

docs/javaone/
  slides.html   ← you are here
  lab.md        ← hands-on instructions