[Natanael_L]

It would require the programs to explicitly describe their actions to the shell and by default behaving in a reversible manner. That would allow you to single out effects you dislike, and tell it to undo it.

Kind of like making the shell behave in relation to your OS as an editor/IDE + version control system, rather than just as an editor/IDE. Old versions are preserved until you purge them.

Or perhaps it would just simulate state changing actions by default, waiting to be told to execute them.