Default completion UI with auto update

I recommend to use Vertico for best performance and an intuitive UI. Nevertheless the default completions buffer UI works decently and supports automatic update in newer Emacs versions. I suggest the following configuration on Emacs 31:

(setq
 ;; One column view with annotations
 completions-format 'one-column
 completions-detailed t
 completions-group t
 ;; Sort candidates by history position
 completions-sort 'historical
 ;; Allow navigating from the minibuffer
 minibuffer-visible-completions 'up-down
 ;; Show completions eagerly and update automatically
 completion-eager-update t
 completion-eager-display t
 completion-auto-help 'always
 ;; Disable noise in the *Completions* buffer
 completion-show-help nil)

;; Unbind `minibuffer-complete-word'
(keymap-unset minibuffer-local-completion-map "SPC")