feat: Hammerspoon IPC cursor tracking + split magnifier (SPC z m)

config.el

@@ -814,25 +814,102 @@ Keeps the status bar and tab bar fully visible at any zoom level.")
           my/zoom-saved-steps nil)))
 
 
+;;; ============================================================
+;;; ACCESSIBILITY — SPLIT-SCREEN MAGNIFIER (SPC z m)
+;;; ============================================================
+;; Split view: LEFT 40% = normal editing, RIGHT 60% = zoomed indirect buffer.
+;; The zoomed pane follows cursor position via post-command-hook sync.
+;; Useful for presentations or low-vision pairing.
+;;
+;; SPC z m  toggle split magnifier on/off
+
+(defvar my/mag-zoom-level 4
+  "Text scale level for the magnified pane (4 ≈ 2× size).")
+
+(defvar my/mag--active nil "Non-nil when split magnifier is enabled.")
+(defvar my/mag--window nil "The magnified (right) window.")
+(defvar my/mag--buffer nil "The indirect buffer used for magnification.")
+
+(defun my/mag--sync ()
+  "Sync magnified pane to current cursor position."
+  (when (and my/mag--active
+             my/mag--window
+             (window-live-p my/mag--window)
+             my/mag--buffer
+             (buffer-live-p my/mag--buffer))
+    (let ((pt (point)))
+      (with-selected-window my/mag--window
+        (goto-char pt)
+        (recenter)))))
+
+(defun my/mag--enable ()
+  "Enable split-screen magnifier."
+  (let* ((base-buf (current-buffer))
+         (mag-name (format "*mag:%s*" (buffer-name base-buf))))
+    ;; Clean up stale buffer
+    (when-let ((old (get-buffer mag-name)))
+      (kill-buffer old))
+    (setq my/mag--buffer (make-indirect-buffer base-buf mag-name t))
+    ;; Split: left 40%, right 60%
+    (delete-other-windows)
+    (setq my/mag--window
+          (split-window (selected-window)
+                        (floor (* 0.4 (window-total-width)))
+                        'right))
+    (set-window-buffer my/mag--window my/mag--buffer)
+    (with-selected-window my/mag--window
+      (text-scale-set my/mag-zoom-level)
+      (setq-local cursor-type nil)
+      (setq-local scroll-margin 0))
+    (setq my/mag--active t)
+    (add-hook 'post-command-hook #'my/mag--sync)
+    (message "Split magnifier ON (zoom %+d)" my/mag-zoom-level)))
+
+(defun my/mag--disable ()
+  "Disable split-screen magnifier."
+  (remove-hook 'post-command-hook #'my/mag--sync)
+  (when (and my/mag--window (window-live-p my/mag--window))
+    (delete-window my/mag--window))
+  (when (and my/mag--buffer (buffer-live-p my/mag--buffer))
+    (kill-buffer my/mag--buffer))
+  (setq my/mag--active nil
+        my/mag--window nil
+        my/mag--buffer nil)
+  (message "Split magnifier OFF"))
+
+(defun my/mag-toggle ()
+  "Toggle split-screen magnifier on/off."
+  (interactive)
+  (if my/mag--active
+      (my/mag--disable)
+    (my/mag--enable)))
+
+
 ;;; ============================================================
 ;;; ACCESSIBILITY — MACOS ZOOM CURSOR TRACKING (SPC z t)
 ;;; ============================================================
-;; Warps mouse pointer to text cursor so macOS Zoom ("Follow mouse cursor")
-;; tracks editing position. Uses window-absolute-pixel-position (Emacs 26+)
-;; paired with set-mouse-absolute-pixel-position — no manual coordinate math.
+;; Writes cursor screen position to ~/.emacs-cursor-pos for Hammerspoon.
+;; Hammerspoon posts a real mouseMoved HID event — required for macOS Zoom
+;; "Follow mouse cursor" (CGWarpMouseCursorPosition is silently ignored).
 ;;
-;; Debounced via run-with-idle-timer 0.05s: rapid j/k spam produces one warp.
+;; Debounced via run-with-idle-timer 0.05s: rapid j/k spam produces one write.
 ;; CCM compatible: idle timer fires after ccm recenter + redisplay.
 ;;
 ;; SETUP macOS: System Settings → Accessibility → Zoom → Full Screen
 ;;   "When zoomed in, the screen image moves: Continuously with pointer"
+;; SETUP Hammerspoon: copy hammerspoon/cursor-warp.lua to ~/.hammerspoon/
 ;;
 ;; SPC z t  toggle cursor tracking on/off
 
 (defvar my/warp-timer nil "Debounce timer for cursor warp.")
 
+(defvar my/cursor-pos-file (expand-file-name "~/.emacs-cursor-pos")
+  "File path for Hammerspoon cursor tracking IPC.")
+
 (defun my/warp-mouse-to-cursor ()
-  "Schedule debounced mouse warp to current cursor position."
+  "Write cursor screen position to file for Hammerspoon to pick up.
+Hammerspoon posts a real mouseMoved HID event — required for macOS Zoom
+'Follow mouse cursor' (CGWarpMouseCursorPosition is silently ignored by Zoom)."
   (when my/warp-timer (cancel-timer my/warp-timer))
   (setq my/warp-timer
         (run-with-idle-timer 0.05 nil
@@ -840,7 +917,14 @@ Keeps the status bar and tab bar fully visible at any zoom level.")
             (setq my/warp-timer nil)
             (when (display-graphic-p)
               (when-let ((pos (window-absolute-pixel-position)))
-                (set-mouse-absolute-pixel-position (car pos) (cdr pos))))))))
+                ;; Write screen-absolute coords for Hammerspoon
+                ;; Also write frame-position for Hammerspoon cross-check
+                (let* ((fp (frame-position))
+                       (content (format "%d %d\n%d %d\n"
+                                        (car pos) (cdr pos)
+                                        (car fp) (cdr fp))))
+                  (with-temp-file my/cursor-pos-file
+                    (insert content)))))))))
 
 (defun my/refresh-frame-position ()
   "Workaround for bug#71912: stale frame position after sleep/fullscreen."
@@ -872,7 +956,8 @@ Keeps the status bar and tab bar fully visible at any zoom level.")
        :desc "Zoom out (÷1.5)"     "-" #'my/zoom-out
        :desc "Reset na výchozí"    "0" #'my/zoom-reset
        :desc "Restore předchozí"   "z" #'my/zoom-restore
-       :desc "Toggle cursor track" "t" #'my/cursor-zoom-mode))
+       :desc "Toggle cursor track" "t" #'my/cursor-zoom-mode
+       :desc "Split magnifier"     "m" #'my/mag-toggle))
 
 
 ;;; ============================================================