Covenants (OP_CTV, OP_CAT)
Also · OP_CTV · OP_CAT · CheckTemplateVerify
Covenants are proposed Bitcoin script features that restrict how a coin may be spent in the future. OP_CTV and OP_CAT are the 2 best-known proposals, neither activated.
Today a Bitcoin script decides who may spend an output. A covenant would also let it decide where the coins can go next. That opens the door to vaults with enforced delays, to batching many users into 1 output, and to layer 2 designs that no longer need every participant online to pre-sign exits.
OP_CHECKTEMPLATEVERIFY, described in BIP119, commits to an exact template of the spending transaction. It is narrow and predictable by design. OP_CAT, in BIP347, revives an old opcode that concatenates stack items and, combined with existing tricks, enables far more general constructions. Both require a soft fork. The debate is about how much expressiveness Bitcoin should take on, and at what risk.
In French · Covenants (OP_CTV, OP_CAT)
