Careful! Just because you are exchanging messages via sockets does not necessarily make it a mere aggregate! Quoting the official GPL FAQ:
> By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs. So when they are used for communication, the modules normally are separate programs. But if the semantics of the communication are intimate enough, exchanging complex internal data structures, that too could be a basis to consider the two parts as combined into a larger program.
Oh that sounds like the official SuperCollider stance might be that any use of scsynth from an existing project via the network OSC API is considered an aggregate. Is this the case?
I definitely don’t want to create any issues and it would be great to get some clarity here.
I don't think that the SuperCollider team has an official stance on this and I can't really speak for all developers. Legally, I think you're on the safe side as long as scsynth runs in a separate process (which is the case for Sonic Pi). However, it's probably against the intentions of James McCartney. If he had wanted scsynth to be used by non-GPL programs, he would have released it under the LGPL. But that's just my assumption. If you're in doubt, just ask him :)
also keep in mind that the gnu.org want gpl to apply as widely as possible. Generally, your approach should be fine imo
that too could be a basis to consider the two parts as combined into a larger program.
That would not stand up in court. This battle has been fought before. Interoperability is not a trojan horse to spread the GPL anymore than it is a trojan horse to impose copyright restrictions by private software.