All of my caravan cards have disappeared from my inventory. I was more or less methodically buying up cards I did not have with the assumption that there was some reward for getting them all. Now they have all disappeared, yet cards to buy still appear in the inventory of merchants. I know for a fact that the cards you can buy from merchants change during the game. How I am I supposed to know which cards I haven't bought are now appearing in merchants' inventory unless I can see which cards I have already bought?