Re: recover-session doesn't

[Richard Stallman]

    Some notes on the Help here ... the help on edebug-defun didn't make
    it clear *how* to select the top-level form on which it acts;

I will improve that doc string--thanks.

    I take it I *can* use the debugger, in particular edebug-defun,

"The debugger" in Emacs Lisp is not the same thing as Edebug.

To step through a function, with Edebug or with the Lisp debugger, you
need to evaluate the interpreted (source code) definition of the
function.

Have you read the chapter on Debugging in the Emacs Lisp Manual?