Macro assert_always_less_than 

macro_rules! assert_always_less_than {
    ($val:expr, $thresh:expr, $message:expr) => { ... };
    ($val:expr, $thresh:expr, $message:expr, { $($key:expr => $dval:expr),+ $(,)? }) => { ... };
}

Assert that val < threshold always holds.

Does not panic on failure — records the violation and logs at ERROR level.