elemsizeofc drilled a 2D `[N][M]T` base's OUTER-index stride down to the
scalar T (the documented elemsizeof FOOTGUN: it bottoms out at the inner
prim size, 4 for [M]u32). The `direct != 8` short-circuit then returned
that scalar size, so wwstage emitted esz=$4 where cstage emits $12 (the
sub-array size, idx_eff(bt)->sub->size = sub.size*elen, type.c:121). The
runtime stayed self-consistent (write+read the same wrong stride) so it
masked until a CROSS-CELL access — a[0][j] and a[1][j] alias.
Fix: detect a nested-array element ([M]T inside [N][M]T) before the
short-circuit and return the element-array tinfo's natural .size, the
sub-array stride. wwstage-only; aligns up to cstage. w6c unchanged.
949 rows: nest2d_u32/u8/i32 (cross-cell write+readback, byte-id).
Hojun-Cho
33bd2b1054