pub fn leaf_cosign_taproot(
user_pubkey: PublicKey,
server_pubkey: PublicKey,
expiry_height: BlockHeight,
unlock_hash: UnlockHash,
) -> TaprootSpendInfoExpand description
The taproot of the leaf policy, i.e. of the output that is spent by the leaf tx
This output is guarded by user+server key and a hash preimage.
The internal key is set to the MuSig of user’s VTXO key + server pubkey, but the keyspend clause is currently not used in the protocol.