Function extract_request_data 

pub async fn extract_request_data(
    req: Request<Incoming>,
    protocol_label: &str,
    status_tx: &UnboundedSender<String>,
) -> Result<RequestData, BodyTooLarge>

Extract request data from hyper Request.

The body is bounded by MAX_REQUEST_BODY_BYTES; a larger one yields BodyTooLarge and the caller answers 413 without spending an LLM call.