Cool project. You could also use the front-end of GNU chess to save some lines, and implement only a back-end.

Bug report:

    a b c d e f g h
  8 r n b q k b n r 8
  7 . . p p p p p p 7
  6 . p . . . . . . 6
  5 p . . . . . . . 5
  4 P . . P P . . . 4
  3 . . . . . . . . 3
  2 . P P . . P P P 2
  1 R N B Q K B N R 1
    a b c d e f g h
  move: b2b3
  ai: b6b4

Thanks for pointing it out! I will try to patch it.

Appreciate you taking the time to test it.