For four decades, China's export machine lifted hundreds of millions from poverty and reshaped the architecture of global commerce — but every model carries within it the seeds of its own limits. Today, a trade surplus swollen to 1.2 trillion dollars and a domestic economy burdened by property distress and demographic decline have left Beijing dependent on markets that are no longer willing to absorb without consequence. The United States and Europe are raising walls, and former trade officials are warning that the collision between China's need to export and the world's capacity to receive ma