> For me, using Fuzzilli for testing a Zig code is not fuzzing, it's integration testing. If you're running code externally (e.g. wrapping binary) you cannot guarantee that side effect isn't caused by IO. I consider fuzzing a low level activity with many external variables removed.

I've never heard anyone restrict the definition of "fuzzing" in this way. If I repeatedly generate inputs to a program and then run the program with those inputs, that's fuzzing. It doesn't matter if there's IO or not.

> Depending on where you are and how you communicate semantics matter more or less. It's very similar to compiler/transpiler. E.g. TypeScript "Compiler" is called compiler but in fact it's transpiler (it emits other high-level language as a result).

It's still a compiler. It translates code from one language to another. You can argue whether we need the term "transpiler," but a source-to-source compiler is a compiler.