Emacs Hydra: Allow completion when I can't remember the command name

| emacs

So it turns out that I'm pretty much zonked after a day with the kiddo and have a hard time remembering keystrokes or speed-reading my Hydra cheat sheets. I want to be able to use M-x-like completion in my Hydra so that I can type a few characters and then maybe see the shortcuts there. Here's what it looks like:

Screenshot_20210425_232535.png

Figure 1: Hydra completion

(defun my/hydra-format-head (h)
  (let ((key-binding (elt h 0))
        (hint (elt h 2))
        (cmd (and (elt h 1) (prin1-to-string (elt h 1)))))
    (if cmd
        (format "%s (%s) - %s" hint key-binding cmd)
      (format "%s (%s)" hint key-binding))))

(defun my/hydra-current-heads-as-candidates ()
  (let ((base (replace-regexp-in-string "/body$" "" (symbol-name hydra-curr-body-fn))))
    (mapcar (lambda (h)
              (cons (my/hydra-format-head h) (hydra--head-name h (intern base))))
            (symbol-value (intern (concat base "/heads"))))))

(defun my/hydra-execute-extended (prefixarg &optional command-name typed)
  (declare (interactive-only command-execute))
  (interactive (let ((execute-extended-command--last-typed nil)
                     (candidates (my/hydra-current-heads-as-candidates)))
                 (hydra-keyboard-quit)
                 (list current-prefix-arg
                       (completing-read "Cmd: " candidates)
                       execute-extended-command--last-typed)))
  (let* ((candidates (my/hydra-current-heads-as-candidates))
         (bind (assoc-default command-name candidates 'string=)))
    (cond
     ((null bind) nil)
     ((hydra--callablep bind) (call-interactively bind)))))

This is how I add it to all my hydras: 

(with-eval-after-load 'hydra
  (define-key hydra-base-map (kbd "<tab>") #'my/hydra-execute-extended))

Proooobably works? Very rough. Might be useful for those fuzzy-brain days.

This is part of my Emacs configuration.
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