But the * suffix marks functions which might stagger their execution over multiple frames. If a function calls fire-arc* , then that function should also have the * suffix; otherwise, the suffix would be meaningless.

You're asking for the ability to refactor a synchronous function into an asynchronous function without needing to review the function's callsites. By definition, this would come with a high price: when writing a step handler, you'd need to assume that any function call could be refactored so that it doesn't return until several frames in the future. Even for a Lisp, that seems chaotic!