What is the ruling on an oath sworn not to do something until Wednesday, then it became clear that today is Wednesday itself and a specific week was not intended; is the oath considered to have ended, or does it extend to next week's Wednesday?

It appears that whoever takes such an oath does not intend the day of his oath, but rather intends to prevent himself from the sworn-upon thing for a period of no less than a day. As long as the questioner did not know at the hour of his oath that the day was Wednesday, then his oath is to be construed as referring to the following Wednesday, because construing it as referring to the day of the oath negates the duration of the oath and contradicts his intention. And intention and cause particularize and restrict oaths.