For two days in Beijing last week, U.S. President Donald Trump and Chinese leader Xi Jinping leaned into the familiar theater of great-power diplomacy. Trump said it was an “honor” to be Xi’s friend and predicted the U.S.-China relationship would be “better than ever before.” Xi, more subtly, used ceremony and symbolism to appeal to Trump’s sense of history and deal-making. All that spectacle yielded a modest yet marketable outcome.