[JackSlateur]

My guess is that most stuff is part of a bigger whole, and so it rots (unless it is adapted to that ever-changing whole)

Of course, you can have stuff running is constraint environment

[ordersofmag]

Or more likely the 'whole' accesses the stable bit through some interface. The stable bit can happily keep doing it's job via the interface and the whole can change however it likes knowing that for that particular tasks (which hasn't changed) it can just call the interface.