[tmerr]

That's a great question. What I've seen is versioning de emphasized. Good unit & integration test coverage to prevent refactor breakage. And when you make a large change that affects consumers of your library, you find a way to do it incrementally. E.g. instead of changing a function's parameters, you can create a second function, migrate everyone over, then delete the old one. And of course, you would not ordinarily modify another teams code without first getting their LGTM.