TemplateHash (Bitcoin Core Dev Tech, May 2026)

TemplateHash is a covenant primitive in the CheckTemplateVerify (CTV) lineage that lets a transaction commit, within itself, to information about its child — outputs, locktime, and so on. It has been published and merged into the repository as a proposed opcode, with the next steps being deployment in Bitcoin Inquisition (a signet for testing consensus changes) and building demonstrated use cases.

The motivating use cases — channel and multiparty factories, simpler PTLCs (reducing interactivity and signing round-trips by allowing initial signatures to be reused), and especially Ark, which multiple teams are now building — are presented as stronger than the older congestion-control motivation, and some argue the proposal is a security upgrade alongside CheckSigFromStack (CSFS). It overlaps usefully with CheckContractVerify (CCV) for vault-like constructions where an output's full value must go to a specified address. Progress is resource-constrained (an author is also driving consensus-cleanup soft forks) and depends partly on whether Ark takes off; PSBT and Miniscript developers are asked to review the BIP, tooling, and motivations.