We want to have an auto-save feature that takes the content of an editor and all the flags and everything else in the form and send it to the server via AJAX as a temporary save (or auto-draft.)

More or less, if the user comes back after losing his connection, he will see what was auto-saved and not the current state. (i.e. a special revision, if you wish.)

The auto-save must be fully secure just like the regular submit button.

Assuming that he Submit is also an AJAX POST, then we don't need to duplicate the work (especially because we'd want the page to auto-update, etc.) the only thing we need is a value to define what should happen when the server receives the POST.

See: AJAX feature (Inline Editing) [core]

See: Editor feature [core]