Most usage-based APIs I have paid for charge by length. Tokens, calls, rows, seconds of video. It is a proxy for value, and it quietly pays a model to pad: the same question answered in four sentences earns more than the one answered in one. I wanted to see what happens if the price is decided after the work instead, by something that reads the result. The payment layer already allowed the shape of this: authorize a ceiling before the work starts, settle less after it. What it could not ...