Game: 102833825
Kingdom had the Peasant-Teacher pile. I had Teacher already played, and on my next turn I chose the "Plus Card" option and selected the Peasant (etc) pile. But, when I later played my Soldier or Fugitive or Discipline cards, I did not get the expected +card bonus.
The text of Teacher is pretty straightforward: "...When you play a card from that pile..." In the DominionStrategy Wiki for Teacher, nothing mentions that only the topmost card in a pile is considered to be from that pile. This current implementation would obviously affect any Kingdom with Knights, as well as all other types of split piles.
Is this the intended play, or, is this a bug? (I don't particularly care; if it's actually working as intended, it's just a matter of adjusting strategy in future games.)
With travellers the upgrades are not in the same pile as the card in supply, so this is working correctly.
It does work properly for split piles, such as Knights or Townsfolk.