Function lumen_signal_get_int64 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn lumen_signal_get_int64(
    name: *const c_char,
    out: *mut i64,
) -> LumenStatus

Read a scalar signal as a 64-bit signed integer, typed. Returns LumenStatus::ErrBadArg when the signal holds no number.

Peeks the foundation typed-property bus snapshot first (catches pending pre-run writes that haven’t been drained yet) before falling back to the local cache.