Built into sdx?
"The point of using starsync is that it transfers only what's needed, and that it uses MK transactions, so the change to <app> is 100% safe regardless of errors, even across power failures. The rest of the process need only concern itself with making sure <tmp> and <bat> get cleaned up, which is *far* less crucial, even if not 100% perfect. Maybe <bat> could even be omitted, by having the new <app> delete <tmp> after everything else is done."