In your solution version is the key to uniqueness. But we can't delete old versions of framework owned by some dropped-its-connection user logged in as another user. And even if we implement 'cleaner' that will run after connection, but before execution, we still won't solve the problem of garbage left in home/tmp directory. I prefer think of uniqueness as username, $TTY, login time and ip address (we can get it with `w`).