What message types does Spring AI support in a Prompt?

A Prompt in Spring AI wraps a list of typed Message objects that correspond directly to the role-based message structure used by modern LLM APIs. Spring AI defines four concrete message types:

When you build a Prompt manually you construct these objects yourself:

List<Message> messages = List.of(
    new SystemMessage("You are a concise code reviewer. Focus on correctness."),
    new UserMessage("Review this method:\n" + code)
);
Prompt prompt = new Prompt(messages,
    OpenAiChatOptions.builder().temperature(0.2).build());
ChatResponse response = chatModel.call(prompt);

In practice, when using ChatClient you rarely construct message objects directly — the .system() and .user() builder methods create them under the hood. You only need to deal with AssistantMessage and ToolResponseMessage explicitly when managing your own conversation history or implementing custom tool loops.

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