Add Rust SDK variant following Go SDK pattern

[Copilot]

Adds a complete Rust SDK for programmatic access to the GitHub Copilot CLI.

Core Implementation

• rust/src/client.rs - Client struct managing CLI process lifecycle, session creation, tool call handling
• rust/src/session.rs - Session struct with event subscription, message sending, tool registration
• rust/src/jsonrpc.rs - JSON-RPC 2.0 client for stdio transport
• rust/src/types.rs - All data types (ClientOptions, SessionConfig, Tool, SessionEvent, etc.)

Build & Docs

• Cargo.toml with tokio, serde, uuid dependencies
• README with API reference and usage examples
• Cookbook scaffold at cookbook/rust/
• Updated root README and justfile with Rust targets

Usage

use copilot_sdk::{Client, SessionConfig, MessageOptions, SessionEventType};
use std::sync::Arc;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new(None);
    client.start().await?;

    let session = client.create_session(Some(SessionConfig {
        model: Some("gpt-5".to_string()),
        ..Default::default()
    })).await?;

    session.on(Arc::new(|event| {
        if event.event_type == SessionEventType::AssistantMessage {
            println!("{}", event.data.content.unwrap_or_default());
        }
    })).await;

    session.send(MessageOptions {
        prompt: "Hello!".to_string(),
        ..Default::default()
    }).await?;

    Ok(())
}

Original prompt

Add a Rust SDK variant, following the example of the Go SDK

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.