Think of it as backward compatible progressive enhancement. You're opting in to veiled FS by making an initial call to unveil a path. The system drops the veil,

Think of it as backward compatible progressive enhancement. You're opting in to veiled FS by making an initial call to unveil a path. The system drops the veil, but only if you indicate that you want to operate in the veiled environment. Subsequent versions could be veiled by default, requiring calls to `unveil` for everything, but obviously that would break every existing program.