The OP_CHECKCONTRACTVERIFY opcode allows a script to inspect state data, perform computations and require its updated commitment in a specified output, thereby enforcing state transitions directly on the blockchain. Its default, deduct and ignore modes impose different constraints on amounts, while dedicated inputs and outputs enable flexible transaction-fee payments. Combining OP_CHECKCONTRACTVERIFY with OP_CAT makes it possible to construct and verify Merkle proofs using, alongside the Taproot script tree, a separate state tree that commits to the intermediate steps of a computation. This architecture could support optimistic fraud-proof systems, where only the disputed computation is verified on-chain without relying on Lamport one-time signatures or the presigned transaction graphs used by BitVM. Combined with OP_CAT, the opcode also enables vaults with functionality equivalent to OP_VAULT, which James O’Beirne considers effectively superseded by this more general and robust design.
Source: Read the original article
