I meant specifically revision control. JetBrains' school of thought is very much AST-centric, yes.

I think MPS stores projects as serialized ASTs and can do VCS merging.

Great. But MPS is not a revision control system.

Ah I see. You mean they were trying to build a custom VCS that had special support for AST merging. MPS uses regular git with custom merge drivers to do AST-level merging instead of textual merging, but that's a bit different