Payjoin-LDK integration discussing with Camillarhi

[zealsham]

we identified the 3 cases where a payjoin transaction can be use on ldk

1. Channel Funding transaction
2. Channel closing transaction
3. Splicing transaction

The idea is to add a payjoin module into ldk-node that allows ldk to perform payjoin transaction and then use that for the various cases above.

This will only support payjoin-V2

[zealsham]

We have lots of question regarding how this should work. since funding transaction in the lighning network is mostly sent to a multisig address, who becomes the receiver here to generate the payjoin url. do the both parties individually do a payjoin and then pay to the funding address.

we want to schedule a call with Tnull to brainstorm on this while also studying this pr lightningdevkit/ldk-node#295 that once tried to implement payjoin

The ldk kvstore is an interesting bottle neck we need to overcome, since we have to save the payjoin persister session event into the ldk-node kvstore.

[tnull]

we want to schedule a call with Tnull to brainstorm on this while also studying this pr lightningdevkit/ldk-node#295 that once tried to implement payjoin

Cool, yeah, let's coordinate via Discord on when to meet.

The ldk kvstore is an interesting bottle neck we need to overcome, since we have to save the payjoin persister session event into the ldk-node kvstore.

Yeah, AFAICT it should currently be straightforward, the only stumbling block might be that very soon we want to drop any blocking IO from LDK Node, at which point we might need an async variant of SessionPersister.

[spacebear21]

Incidentally I started working on an AsyncSessionPersister POC yesterday!

[Camillarhi]

I will reach out to Tnull to schedule the call so we can brainstorm on this.