Expanding Taproot Miniscript and MuSig2 support

[odudex]

Hi! 👋

@pythcoiner put together a branch adding Taproot Miniscript and MuSig2 support, and I've been tweaking it. It's now running in Kern, an ESP32P4-based air-gapped signer, where Taproot Miniscript is operational, loading and validating descriptors, signing key-path and script-path.

Branch (based on release_1.5.4): https://github.com/odudex/libwally-core/tree/tapscript-and-musig2

We'd really love to upstream this and work together with you to mature it, we think collaborating would make it more robust and reliable for everyone, and we're happy to help in whatever way works best for you.

So the main question: Is this something you'd be open to collaborating on? If so, how would you like us to shape it (e.g. split into smaller PRs, anything else you'd need)?

Thanks for libwally-core! It's been great to build on. 🙏

[jgriffiths]

Hi @odudex I previously reached out to @pythcoiner to discuss exactly this. We'd love to take the changes!

If you believe your branch is now stable and ready to merge, please rebase and open a pull request to merge it to current wally master. Given the size of the changes the approach I suggested is that I will create a merge branch and add commits from your PR to it as they are reviewed/accepted. Then if needed you can always rebase your branch and we should be able to stay in sync while we work through it. LMK if that sounds OK to you.

[jgriffiths]

@odudex Just taking a quick look at your branch, ideally you would take the fixes you have made and merge them back to the commit where the problem they fix was added. In some cases you might need to split up a commit if it has multiple unrelated fixes. If I have to do that while merging we will lose the ability to sync/rebase any other changes I have to make along the way...

[odudex]

ideally you would take the fixes you have made and merge them back to the commit where the problem they fix was added

I thought that would be necessary. I just rebased @pythcoiner 's work to master than added the fixes as follow-ups, but that would be complicated to review indeed.
I'll do a few more rounds of tests and optimizations, then do my best to clean commit history rebasing fixes to appropriate commits, and make a gradual review to a merge branch viable.

[jgriffiths]

Awesome, thanks!