<dependency>
    <groupId>dev.langchain4j</groupId>
    <artifactId>langchain4j-anthropic</artifactId>
    <version>1.16.1</version>
</dependency>
<!-- swap for langchain4j-open-ai, langchain4j-google-ai-gemini, langchain4j-ollama -->

// ChatModel is LangChain4j's provider-agnostic interface
ChatModel model = AnthropicChatModel.builder()
    .apiKey(System.getenv("ANTHROPIC_API_KEY"))
    .modelName("claude-sonnet-4-6")
    .maxTokens(1024)
    .build();

var transport = new StdioAcpAgentTransport();

AcpSyncAgent agent = AcpAgent.sync(transport)
    // Identical to the echo agent (Module 12)
    .initializeHandler(req -> InitializeResponse.ok())
    .newSessionHandler(req ->
        new NewSessionResponse(UUID.randomUUID().toString(), null, null))

    // The only change from echo: ask the model
    .promptHandler((req, context) -> {
        String answer = model.chat(req.text());
        context.sendMessage(answer);
        return PromptResponse.endTurn();
    })
    .build();

agent.run();

export ANTHROPIC_API_KEY=sk-ant-...
./mvnw package -pl module-27-langchain4j-chatbot -q
./mvnw exec:java -pl module-27-langchain4j-chatbot