I believe the original idea was indeed developed before publication of the taproot and tapscript BIPs, but drafts of those BIPs were published about two weeks before OP_COSHV, the predecessor for CTV. Versions of both the
COSHV and STB BIPs linked to the draft Tapscript BIP and depended on it making OP_RESERVED1 (0x89) opcode into an OP_SUCCESSx in tapscript.
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