adamwinterI am afraid you seem to have misunderstood the concept of mutable files. The mutability is not two sided, i.e. the change in the sandbox does cause a change on the host OS.
In this case, "immutable files" are those that do not get copied to the sandbox; the sandbox emulates a read-only copy of them and gets their actual bytes from the host OS. "Mutable files" get copied to the sandbox.
Published Dec 19, 2018
Version 1.0