In a mailing list post Z-man details a PTLC construction which he claims is "is almost entirely a MuSig ritual". My question is whether this MusigTweak is what is called the
adaptor (last argument of
secp256k1_musig_session_combine_nonces) in secp256k1-zkp? And has in fact been implemented?
How is MusigTweak computed? Is it the per-hop tweaked payment point, which means it will be the payment point for the hop connecting to the payer?
In a way, that wouldn't make sense since MusigTweak takes three arguments, and the payment point is the same for both channel partners. But on the other hand, maybe Z-man is describing how the tweaking works internally in libsecp256k1-zkp, and I can safely just use the tweaked payment point for both peers for the
adaptor argument because the implementation will treat the adaptor differently depending in the index of the signer?