Two of the world's most consequential leaders will meet next week in Washington, where the rituals of diplomacy — an airport greeting, a Rose Garden review, a candlelit state dinner — will serve as the visible grammar of an invisible negotiation. President Trump's decision to receive Xi Jinping at Joint Base Andrews, departing from the convention of White House reception, is the kind of deliberate gesture that diplomats spend careers learning to read. Behind the ceremony lies a set of questions that will shape the coming decade: how two rival powers manage trade, who controls the minerals that