Formal verification

Mathematical proof that a contract's behavior matches its specification.

Formal verification uses mathematical methods to prove that a smart contract's code behaves exactly according to a formal specification. Unlike audits (which look for bugs), formal verification proves the absence of certain bug classes within the specified scope. It's expensive, time-consuming, and requires the team to write a precise specification.

Formal verification is most valuable for high-stakes, long-lived primitives — lending pools, stablecoin minting, bridges. It's less useful for fast-evolving application logic where the spec changes weekly.