(So far this looks right. Having the defaults correctly detected for the common pieces means all that needed to be checked here is promotion and castling; really nice H.G.! But specifying promotion choices seemed finicky; without explicitly giving the knight's label it wasn't recognized, and depending on the order of the promotion choices I lost other choices as well.)
Here's a diagram with a playable AI (my first, so let's see how this goes):
(So far this looks right. Having the defaults correctly detected for the common pieces means all that needed to be checked here is promotion and castling; really nice H.G.! But specifying promotion choices seemed finicky; without explicitly giving the knight's label it wasn't recognized, and depending on the order of the promotion choices I lost other choices as well.)