What is priced instead

In a proof-carrying chain, computation cost falls on whoever produces the proof, which is the submitting party, so computation is self-priced and a deliberately expensive predicate harms only its author. The network's scarce resources are therefore bytes and persistent state, and the fee model prices exactly those: transaction size, and state occupancy [A]. The live precedent for pricing occupancy is Ergo's storage rent on long-unspent state, which Ergo's own documentation frames as making state growth controllable and predictable [S].