Function return_prebuilt 

pub unsafe fn return_prebuilt(
    bytes: &[u8],
    result_buf: *mut *mut u8,
    result_len: *mut usize,
) -> i32

Copy pre-serialized bytes into a fresh allocation and hand it to the framework.

Used by generated_list_* functions that cache their JSON response in a OnceLock<Vec<u8>>. Each call does one memcpy instead of rebuilding the Value tree and re-serializing.

Safety

Same requirements as return_success.