The selected state used a pale tonal container (seedPrimaryContainer)
that sat almost on top of the pale canvas, so 'on' barely read. Selected
chips now fill solid — seedGreen for the plain attribute/market chips and
the swatch's own ink for family/form chips — with white label, icon and
checkmark. Idle chips stay light with dark ink, so the on/off jump is
unmistakable. White-on-ink AA is locked by a new contrast test.
For help getting started with Flutter development, view the
online documentation, which offers tutorials,
samples, guidance on mobile development, and a full API reference.