Nice. One thing you might want to add. From reading you present two ways to deal with restarts:
1) interactive debugger
2) programmatical
There is another one:
3) restart dialog
The program presents you a list of restarts, for example in a GUI dialog, and the end user can select a restart - without interacting with a debugger.
The debugger is just one program, which may display the restarts.
That's how one used it in applications on a Lisp Machine. To call a debugger could be an option in the list of restarts. For real real end users, even the call to the debugger might not be available and all they can do is to choose an option from the list of restarts. Symbolics offered something called 'Firewall', which did all it can to hide the underlying Lisp system from the end user - here the end user should not interact with a debugger or Lisp listener.
But even in a Lisp listener, if you used the 'Copy File' command you might get a dialog shown with the typical options: abort, try again, use other file, enter debugger, ...
Since it happened after I left, I am not privy to the exact reasons for the move. However, I guess they were worried about their Lispers moving away (which to some degree had already happened) and them not being able to find new ones.
