As part of #3350, I think we will probably want to be able to toggle the resolver between "platform specific mode" and "universal mode." The latter requires some behavioral changes in how it does marker evaluation. It would also be useful to use this toggle to improve error handling in some cases. For example, in the former case, resolver forking should never be allowed. So if the universal toggle is disabled, then we shouldn't try to turn an "unresolvable" case into a resolvable case by forking.