For your first point, you might be thinking of ABI and not API? Rust doesn’t have a stable ABI but the API is non breaking as long as you aren’t on nightly AND

For your first point, you might be thinking of ABI and not API? Rust doesn’t have a stable ABI but the API is non breaking as long as you aren’t on nightly AND opting into unstable features. If you stay on stable Rust, you’ll not really have breaking changes between versions. Regarding ABI , that means that if you compile rust into a library with one version, you can’t reuse that compiled library in a newer version of the compiler, unless you go through a stable ABI like exposing a C interface. However if you recompile your code, it’ll work. You need to keep them compiled by the same compiler version.