One rectangle via the multipatch path is bit-identical to the old
single-patch blocked path (both modes, raw masks); S1 two-patch 16x32 equals
the 16x16 one-patch run tiled (bitwise), in both rectangle orders; face
gap-4 pair is order-invariant with exact covered/hole masks. Mass printed
as a diagnostic only.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>