// Tell the agent what we support
var clientCaps = new ClientCapabilities(
    new FileSystemCapability(true, true),  // readTextFile, writeTextFile
    true                                    // terminal
);

client.initialize(new InitializeRequest(1, clientCaps));

// Check what the agent supports
NegotiatedCapabilities agentCaps = client.getAgentCapabilities();
System.out.println("loadSession: " + agentCaps.supportsLoadSession());
System.out.println("mcpHttp: " + agentCaps.supportsMcpHttp());
System.out.println("mcpSse: " + agentCaps.supportsMcpSse());

.initializeHandler(req -> {
    // Read what the client supports
    var clientCaps = req.clientCapabilities();

    // Advertise our own capabilities
    var agentCaps = new AgentCapabilities(
        true,                                    // loadSession
        new McpCapabilities(false, false),        // no MCP
        new PromptCapabilities(false, false, true) // embeddedContext only
    );

    return InitializeResponse.ok(agentCaps);
})

.promptHandler((req, context) -> {
    // Check capabilities before attempting operations
    NegotiatedCapabilities caps = context.getClientCapabilities();

    if (caps.supportsReadTextFile()) {
        String content = context.readFile("/etc/hostname");
    } else {
        // Graceful degradation
        context.sendMessage("File read not supported by client");
    }

    return PromptResponse.endTurn();
})

./mvnw package -pl module-17-capability-negotiation -q
./mvnw exec:java -pl module-17-capability-negotiation