Second Answer
Against one notrump, partner led the three of spades (six, ten, five); you returned the Jack of spades (Ace, two, eight). Declarer likely has only the King remaining. Declarer cashes four rounds of hearts (declarer started with AK7); partner discards the ten of clubs followed by the four of diamonds. What new information did you just receive? The Ace-King of spades and Ace-King of hearts account for 14 of declarer’s 15-17 HCP, so declarer has at most 3 HCP in the minors. Therefore, partner has the club Ace and (unless declarer opened one notrump on 14 HCP) declarer has the diamond King. Declarer calls for dummy’s Jack of diamonds. Here is an updated diagram (dummy is about to lead the Jack of diamonds):
What’s your play: Ace, Queen or seven of diamonds?