There is already a scheme used for encoding parameters that does not require a unique integer id into a lookup table.  return_url works like this, urlencoding the host/path etc. PLUS any query params.  A page which is passed a return_url can itself urlencode that and any other params as the new return_url and pass it on.  The stack unwinds as the pages return.

The need for any of this depends on what you think the context bar is.  Does it show Where You Are, or does it show Where You've Been?

Where You've Been is a dynamic property and has little to do with the structure of the site.  The back button shows where you've been and how to get back there.

Where You Are is why we're confused as we try to re-use chunks of code by bouncing people through pages using redirects.  Setting Permissions is a general concept that we have, it's re-used a number of places in the toolkit; why can't it stand alone as a concept in the navigation?

Perhaps more functionality should be available as includes, to be wrapped up within minimal pages as packages require.  This would at least give us more templating flexibility.  But the proposal above sounds like waay too much work.