Looking at the code it does not seem that edit server save the contents to a file. However it does provide a hook edit-server-done-hook
which running every time you do edit-server-save
(C-xC-s) or edit-server-done
(C-cC-c) you might add a function to the hook to save the current contents to a file.
A not-so-well-tested example is given below
(defvar my-edit-with-emacs-backups-dir (locate-user-emacs-file "edit-with-emacs-saves"))
(unless (file-exists-p my-edit-with-emacs-backups-dir)
(make-directory my-edit-with-emacs-backups-dir))
(defun my-backup-edit-with-emacs-contents ()
(let ((backup-directory-alist (list (cons "." my-edit-with-emacs-backups-dir))))
(save-excursion
(write-region nil nil (car (find-backup-file-name (buffer-name))) nil 0))))
(add-hook 'edit-server-done-hook #'my-backup-edit-with-emacs-contents)
With the above the you edit-with-buffer
contents will be backed up in ~/.emacs.d/edit-with-emacs-saves
directory whenever you do edit-server-save
(C-xC-s) or edit-server-done
(C-cC-c)
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