As someone who worked a bit with Bazel actions and uses Scala: I think Bazel cuts down on the area where arbitrary I/O happens. Also, many executables come from

As someone who worked a bit with Bazel actions and uses Scala: I think Bazel cuts down on the area where arbitrary I/O happens. Also, many executables come from pre-defined targets (e.g. java toolchains). One way to deal with I/O is if Mill injected its own implementation of a JVM filesystem/network layer, which I'm pretty sure it can do.