passes executed.
Test-only count of radix scatter passes executed since that reset.
What makes a test of any pass-count optimisation non-vacuous: the constant-digit skip and the narrow-integer bias both leave the permutation bit-identical, so this is the only thing that can say whether either fired. Zero means the radix path did not run at all, which is itself worth asserting -- a floor or a decline is easy to trip by accident and looks exactly like an optimisation working perfectly.