This resolves most cases of keybinding, but it is not perfect. For example, vi-mode's keymap precedes directory-mode's, so Return doesn't work in directory-mode.

While Lem doesn't have as many layers as Emacs, such as buffer-local keymaps, this kind of problem remains.

Buffer-local keymap and buffer-created hook are required to change keybindings for each mode flexibly.

Without them, it can be achieved by overwriting execute method, like:

(defmethod execute ((mode directory-mode) (command vi-return) uarg)
  (declare (ignore uarg))
  (directory-mode-find-file))

However, M-x describe-key <Return> still says it's bound to vi-return, and all commands have to be overwritten.

Will be fixed in a different way at #1008.