I play an Artificer, I have no other Action cards in hand. The End Actions button disappears, but now there's a new button that says "Don't Discard." I understand that you're trying to make less clicking and you need to explicitly enter the Buy phase for some edge cases.
But the End Actions button does the exact same thing that the Don't Discard button, so it would make a lot of sense to me if the Don't Discard button was at least located where the End Actions button normally is.
But even better, if the player has treasures in their hand, why not display the Autoplay Treasures button where the Don't Discard button is? Seems more intuitive AND less clicking!
I guess you are suggesting to add the [Autoplay Treasures] button, right?
You definitely need a [Don't Discard] or [End Actions] button to allow to play specific treasures only.