If i uncomment the commented code and then press 'U' the pointer jumps back to
the start of the block

#+begin_src emacs-lisp

(defvar
  eshell-toggle-window-configuration nil
  "Variable to store the window configuration before opening eshell.")

(defvar eshell-toggle-selected-window nil
  "Variable to store the selected window before opening eshell.")

(defun SpawnEshellSplitBelow ()
  "Open a shell in a small split below or toggle it if already open."
  (interactive)
  (if (eq major-mode 'eshell-mode)
      (progn
        (when eshell-toggle-window-configuration
          (set-window-configuration eshell-toggle-window-configuration)
          (setq eshell-toggle-window-configuration nil))
        (when eshell-toggle-selected-window
          (select-window eshell-toggle-selected-window)
          (setq eshell-toggle-selected-window nil)))
    (setq eshell-toggle-window-configuration (current-window-configuration))
    (setq eshell-toggle-selected-window (selected-window))
    ;; Calculate one third of the total window height
    (let ((one-third-height (/ (window-total-height) 3)))
      ;; Ensure the height is at least 1 to avoid errors
      (setq one-third-height (max one-third-height 1))
      (split-window-below (- one-third-height))
      (other-window 1)
      (open-eshell-in-current-directory))))

(defun open-eshell-in-current-directory ()
  "Open eshell in the directory of the current buffer.
    If an eshell buffer for the directory already exists, switch to it."
  (interactive)
  (let* ((buffer-dir (if (buffer-file-name)
                         (file-name-directory (buffer-file-name))
                       default-directory))
         (eshell-buffer-name (concat "*eshell:" buffer-dir "*"))
         (existing-eshell-buffer (get-buffer eshell-buffer-name)))
    (if existing-eshell-buffer
        (switch-to-buffer existing-eshell-buffer)
      (let ((eshell-buffer (eshell 'N)))
        (with-current-buffer eshell-buffer
          (rename-buffer eshell-buffer-name)
          (eshell/cd buffer-dir))))))

(with-eval-after-load 'evil
  (define-key evil-normal-state-map (kbd "M-e") 'SpawnEshellSplitBelow)
  (define-key evil-insert-state-map (kbd "M-e") 'SpawnEshellSplitBelow))
;; (define-key evil-normal-state-map (kbd "M-e") 'open-eshell-in-current-directory))

(defun SpawnEshellInProjectRoot ()
  "Open eshell in the project's root directory or toggle it if already open."
  (interactive)
  (if (eq major-mode 'eshell-mode)
      (progn
        (when eshell-toggle-window-configuration
          (set-window-configuration eshell-toggle-window-configuration)
          (setq eshell-toggle-window-configuration nil))
        (when eshell-toggle-selected-window
          (select-window eshell-toggle-selected-window)
          (setq eshell-toggle-selected-window nil)))
    (setq eshell-toggle-window-configuration (current-window-configuration))
    (setq eshell-toggle-selected-window (selected-window))
    ;; Calculate one third of the total window height
    (let ((one-third-height (/ (window-total-height) 3)))
      ;; Ensure the height is at least 1 to avoid errors
      (setq one-third-height (max one-third-height 1))
      (split-window-below (- one-third-height))
      (other-window 1)
      (let ((project-root (projectile-project-root)))
        (open-eshell-in-directory project-root)))))

(defun open-eshell-in-directory (dir)
  "Open eshell in the specified directory DIR.
If an eshell buffer for the directory already exists, switch to it."
  (interactive "DDirectory: ")
  (let* ((eshell-buffer-name (concat "*eshell:" dir "*"))
         (existing-eshell-buffer (get-buffer eshell-buffer-name)))
    (if existing-eshell-buffer
        (switch-to-buffer existing-eshell-buffer)
      (let ((eshell-buffer (eshell 'N)))
        (with-current-buffer eshell-buffer
          (rename-buffer eshell-buffer-name)
          (eshell/cd dir))))))

(with-eval-after-load 'evil
  (define-key evil-normal-state-map (kbd "M-p") 'SpawnEshellInProjectRoot))

(defun kill-all-eshell-buffers ()
  "Kill all Eshell buffers."
  (interactive)
  (dolist (buffer (buffer-list))
    (when (string-match-p "^\\*eshell\\*" (buffer-name buffer))
      (kill-buffer buffer))))


;; (defvar my-saved-window-configuration nil
;;   "Variable to store the saved window configuration.")

;; (defun my-eshell-fullscreen ()
;;   "Replace the current window layout with a fullscreen Eshell."
;;   (interactive)
;;   (setq my-saved-window-configuration (current-window-configuration))
;;   (delete-other-windows)
;;   (eshell))

;; (defun my-restore-window-configuration ()
;;   "Restore the previously saved window configuration."
;;   (interactive)
;;   (when my-saved-window-configuration
;;     (set-window-configuration my-saved-window-configuration)))

(defvar my-saved-tab-configurations (make-hash-table :test 'equal)
  "Hash table to store the saved window configurations per tab.")

(defun my-current-tab-name ()
  "Get the current tab's name."
  (alist-get 'name (car (funcall tab-bar-tabs-function))))

(defun my-eshell-fullscreen ()
  "Replace the current window layout with a fullscreen Eshell for the current tab."
  (interactive)
  (let ((tab-name (my-current-tab-name)))
    (puthash tab-name (current-window-configuration) my-saved-tab-configurations)
    (delete-other-windows)
    (eshell)))

(defun my-restore-window-configuration ()
  "Restore the previously saved window configuration for the current tab."
  (interactive)
  (let* ((tab-name (my-current-tab-name))
         (config (gethash tab-name my-saved-tab-configurations)))
    (if config
        (set-window-configuration config)
      (message "No saved window configuration for this tab."))))

#+end_src