OP VAULT
OP_VAULT was a proposed pair of Taproot script opcodes defined in BIP 345. Together with CHECKTEMPLATEVERIFY (CTV, BIP 119), the opcodes were intended to give consensus support for vault-style custody. A vault locks coins under a delayed withdrawal path while preserving an always-available recovery path. BIP 345 has BIP status Closed, with BIP 443 (OP_CHECKCONTRACTVERIFY) listed as the proposed replacement. The authors withdrew further advocacy for the vault-specific opcodes in May 2025 in favor of that more general covenant design, which can still express vault constructions.
A typical BIP 345 vault is a Taproot output whose script tree contains at least two leaves. One leaf uses OP_VAULT to authorize a trigger spend. The other uses OP_VAULT_RECOVER to send funds to a predetermined recovery destination. Triggering the vault produces an intermediate output that still carries the recovery leaf and replaces the vault leaf with a timelocked CTV script describing the intended withdrawal. After the relative delay elapses, a withdrawal that matches the CTV template can claim the coins. At any time before that withdrawal confirms, a recovery spend can sweep the funds. BIP 345 never activated on Bitcoin mainnet.