(defun z/no-sidenotes-file-p (file)
  "Return non-nil if FILE should be rendered without sidenotes.

A file is no-sidenotes if:
  - It has a #+NO_SIDENOTES: keyword, or
  - Its FILETAGS contain :NO_SIDENOTES: or :KANBAN:, or
  - Any top-level heading contains \"KANBAN\"."
  (when (file-exists-p file)
    (with-temp-buffer
      (insert-file-contents file)
      (org-mode)
      (let* ((case-fold-search t)
             (keywords (org-collect-keywords
                        '("NO_SIDENOTES" "FILETAGS")))
             (flag     (cadr (assoc "NO_SIDENOTES" keywords)))
             (filetags (cadr (assoc "FILETAGS" keywords))))
        (or
         (and flag (string-match-p "\\S-" flag))
         (and filetags
              (string-match-p
               ":\\(NO_SIDENOTES\\|KANBAN\\):"
               (concat ":" filetags ":")))
         (save-excursion
           (goto-char (point-min))
           (re-search-forward "^\\*+ .*KANBAN.*" nil t)))))))
(provide 'sidenotes)