Still working through, but I am a bit hesitant about Struct.abstract and particularly Struct.interfaces (but makes sense why you added). Maybe instead of storing that metadata on the Struct, we add extra arguments to the sgqlc TypeSystem/TypeAdapter to_system methods (defaulting to "type" rather than "interface")? That way, users could still convert pydantic -> arti, but then on conversion to sgqlc, choose to make it an Interface or Type (that should be good enough for our backend needs, where we can know when/what we want)?

That would mean roundtripping Interfaces wouldn't work by default, but I think that's probably ok (and likely unavoidable in some cases... unless we add some extra "metadata" field to each Type. I think parquet allows this, which pandas uses to track things like "Categorical", etc)