◇ Just read — no move neededCannon at the bottom of the sea
海底捞月 is the classic chariot-and-cannon endgame kill: the general and chariot hold the centre file, and the cannon sinks to the very bottom of the board on the king's own file — here d1. It fires through Black's guard rook on d7: the rook cannot capture the mating chariot on d8 (it would merely become the new screen), and the king may never step to e9 because Red's general glares up the open centre.