seplink_test.ww carries the .a substrate legs (root-as-.o layout, .a
byte-id + 3x determinism, the #31 masked-dup PASS-3 reject with its
non-vacuity flip), the loud dependency-cycle reject with byte-equal
cs/ww stderr, and the w6l/w6l_ww bare-main duplicate-symbol reject
(achievable substring parity per the filed message divergence).
