Function lumen_event_type 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn lumen_event_type(
    buf: *mut c_char,
    buf_len: usize,
    out_len: *mut usize,
) -> LumenStatus

Copy the current event’s type name into buf (string-out convention: *out_len excludes the NUL; too-small returns LumenStatus::ErrBufferTooSmall with the required capacity). Valid only inside a LumenEventFn callback. Thread-safe.