lang/org: close agenda buffers after org-agenda

Experimental. Running org-agenda would leave leftover open buffers, this
hook cleans them up.

modules/lang/org/config.el

@@ -241,6 +241,14 @@ between the two."
   ;; Don't open separate windows
   (map-put org-link-frame-setup 'file 'find-file)
 
+  (defun +org|cleanup-agenda-files ()
+    "Close leftover agenda buffers after they've been indexed by org-agenda."
+    (cl-loop for file in org-agenda-files
+             for buf = (get-file-buffer file)
+             if (and file (not (get-buffer-window buf)))
+             do (kill-buffer buf)))
+  (add-hook 'org-agenda-finalize-hook #'+org|cleanup-agenda-files)
+
   ;; Let OS decide what to do with files when opened
   (setq org-file-apps
         `(("\\.org$" . emacs)