I invented auto-restore for Glk-based systems (such as Glulx). It is
described at: http://ifwiki.org/index.php/Auto-restore
Some games have questions that you must answer when starting a new
session before it will let you to restore the game, and this is meant
to avoid that, and may also be wanted for other purposes too maybe. (My
own game doesn't have any such questions but still uses auto-restore.)
There is a Inform7 code there, although I do not use Inform7 (nor
Inform6), so I do not know if that code will even compile.
My own work in progress game (called xyzabcde2) supports auto-restore,
as well as another feature which is the ability for global user
preferences to specify the default verbosity (if the interepreter
supports it, which as far as I know, none do except for ones linked
with my own Enhanced GlkTerm). (But xyzabcde2 is not written in Inform;
it is written in assembly language instead.)
If that Inform7 code works for you, then hopefully it can be included in
the Inform7 extension library (change it if necessary to work). If it
doesn't work, hopefully you would know how to correct it.
(Is there a NNTP to post the Inform7 extensions? Maybe there is a mailing
list, but I think NNTP is much better.)
Note: I am not always able to read/post messages during Monday-Friday.