Function split_system_prompt 

pub fn split_system_prompt(
    messages: &[ChatMessage],
) -> (&[ChatMessage], &[ChatMessage])

Split a message slice into (system_messages, rest).

Takes all leading contiguous System messages (supporting multi-message system prompts) and returns them separately from the remaining conversation messages. This is the recommended way to peel off the system prompt before compressing the conversation body.

Examples

let (sys, body) = split_system_prompt(&messages);
// sys  = [System("You are ..."), System("Extra instructions")]
// body = [User("hi"), Assistant("hello"), ...]