make occur mode interactive

interactive-occur.el

(defvar interactive-occur-timer nil
  "Timer for updating the occur buffer.")

(defvar interactive-occur-delay 0.3
  "Delay in seconds before updating the occur buffer.")

(defun interactive-occur ()
  "Interactively search using occur, updating results as you type."
  (interactive)
  (let ((source-buffer (current-buffer))
        (old-hook minibuffer-setup-hook))
    (unwind-protect
        (progn
          (add-hook 'minibuffer-setup-hook
                   (lambda ()
                     (add-hook 'after-change-functions
                              (lambda (&rest _)
                                (when interactive-occur-timer
                                  (cancel-timer interactive-occur-timer))
                                (setq interactive-occur-timer
                                      (run-with-timer
                                       interactive-occur-delay nil
                                       (lambda ()
                                         (let ((pattern (minibuffer-contents)))
                                           (unless (string-empty-p pattern)
                                             (with-current-buffer source-buffer
                                               (occur pattern 1))))))))
                              nil t)))
          (let ((pattern (read-from-minibuffer "Pattern: ")))
            (unless (string-empty-p pattern)
              (with-current-buffer source-buffer
                (occur pattern))
              (pop-to-buffer "*Occur*"))))
      (setq minibuffer-setup-hook old-hook)
      (when interactive-occur-timer
        (cancel-timer interactive-occur-timer)
        (setq interactive-occur-timer nil)))))

;; Bind it to a key (customize as needed)
(global-set-key (kbd "C-c s") 'interactive-occur)