Yup, building libraries on IO traits which then are implemented by the particular runtimes is a good way to have a runtime agnostic library. Ideally the IO trai

Yup, building libraries on IO traits which then are implemented by the particular runtimes is a good way to have a runtime agnostic library. Ideally the IO traits are defined in the library itself, to make them not again dependent on another moving target. You can provide implementations of the "glue code" for particular runtimes in separate crates to ease integration for users. Another way to be runtime agnostic is to start a particular runtime as part of your library, which is used internally. The public interface of your library can provide async functions which are agonstic to a particular runtime, since all actions will be deferred/forwarded to an internal runtime. That approach has a bit more overhead, but can ease usage.