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")
+;; Writes cursor screen position to ~/.emacs-cursor-pos for Hammerspoon.
-;; tracks editing position. Uses window-absolute-pixel-position (Emacs 26+)
+;; Hammerspoon posts a real mouseMoved HID event — required for macOS Zoom
-;; paired with set-mouse-absolute-pixel-position — no manual coordinate math.
+;; "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))
 
 
 ;;; ============================================================

hammerspoon/cursor-warp.lua

@@ -0,0 +1,105 @@
+-- cursor-warp.lua — Emacs cursor tracking for macOS Zoom
+--
+-- WHAT: Reads cursor coordinates written by Emacs to ~/.emacs-cursor-pos
+--        and posts a real mouseMoved HID event so macOS Zoom follows the
+--        text cursor. CGWarpMouseCursorPosition (used by Emacs internally)
+--        is silently ignored by macOS Zoom — this workaround fixes that.
+--
+-- SETUP:
+--   1. Install Hammerspoon: https://www.hammerspoon.org/
+--   2. Grant Accessibility permission: System Settings → Privacy & Security
+--      → Accessibility → enable Hammerspoon
+--   3. Copy this file to ~/.hammerspoon/cursor-warp.lua
+--   4. In ~/.hammerspoon/init.lua add:  require("cursor-warp")
+--   5. In Emacs: SPC z t enables cursor tracking (writes ~/.emacs-cursor-pos)
+--   6. Toggle in Hammerspoon: call emacsZoomToggle() or bind a hotkey
+--
+-- FILE FORMAT (~/.emacs-cursor-pos):
+--   Line 1: X Y    (screen-absolute cursor position)
+--   Line 2: FX FY  (frame-position, for debug cross-check)
+
+local M = {}
+
+-- Global toggle
+emacsZoomEnabled = true
+emacsZoomDebug = false
+
+local cursorPosFile = os.getenv("HOME") .. "/.emacs-cursor-pos"
+local lastMtime = 0
+local pollTimer = nil
+
+local function readCursorPos()
+    local f = io.open(cursorPosFile, "r")
+    if not f then return nil end
+    local line1 = f:read("*l")
+    local line2 = f:read("*l")
+    f:close()
+    if not line1 then return nil end
+    local x, y = line1:match("^(%d+) (%d+)$")
+    if not x then return nil end
+    local fx, fy = nil, nil
+    if line2 then
+        fx, fy = line2:match("^(%-?%d+) (%-?%d+)$")
+    end
+    return tonumber(x), tonumber(y), tonumber(fx), tonumber(fy)
+end
+
+local function pollAndWarp()
+    if not emacsZoomEnabled then return end
+
+    -- Check file modification time to avoid unnecessary reads
+    local attrs = hs.fs.attributes(cursorPosFile)
+    if not attrs then return end
+    local mtime = attrs.modification
+    if mtime == lastMtime then return end
+    lastMtime = mtime
+
+    local x, y, fx, fy = readCursorPos()
+    if not x then return end
+
+    -- Post a real mouseMoved event (not CGWarp)
+    hs.eventtap.event.newMouseEvent(
+        hs.eventtap.event.types.mouseMoved,
+        hs.geometry.point(x, y)
+    ):post()
+
+    if emacsZoomDebug then
+        local msg = string.format("cursor-warp: move to (%d, %d)", x, y)
+        if fx then
+            -- Cross-check with Hammerspoon's view of Emacs frame
+            local emacs = hs.application.get("Emacs")
+            if emacs then
+                local win = emacs:focusedWindow()
+                if win then
+                    local frame = win:frame()
+                    msg = msg .. string.format(
+                        " | emacs-frame=(%d,%d) hs-frame=(%d,%d)",
+                        fx, fy, math.floor(frame.x), math.floor(frame.y))
+                end
+            end
+        end
+        print(msg)
+    end
+end
+
+function emacsZoomToggle()
+    emacsZoomEnabled = not emacsZoomEnabled
+    local state = emacsZoomEnabled and "ON" or "OFF"
+    hs.alert.show("Emacs Zoom tracking: " .. state)
+    print("cursor-warp: " .. state)
+end
+
+function emacsZoomDebugToggle()
+    emacsZoomDebug = not emacsZoomDebug
+    hs.alert.show("Emacs Zoom debug: " .. (emacsZoomDebug and "ON" or "OFF"))
+end
+
+-- Start polling
+pollTimer = hs.timer.doEvery(0.05, pollAndWarp)
+
+-- Optional hotkey: Ctrl+Opt+Cmd+Z to toggle
+hs.hotkey.bind({"ctrl", "alt", "cmd"}, "Z", emacsZoomToggle)
+
+print("cursor-warp: loaded (polling every 50ms, hotkey Ctrl+Opt+Cmd+Z)")
+
+return M