feat: comprehensive screen magnifier — text-scale + which-key fix + minibuffer

config.el

@@ -701,11 +701,11 @@ Skips past the TODO keyword and optional priority indicator [#A]."
 ;; True screen magnifier: scales the global `default' face (all buffers,
 ;; help windows, doom menus, org-agenda, magit — everything).
 ;;
-;; Modeline + minibuffer are PINNED to base size after every zoom so they
-;; stay fully visible and usable regardless of zoom level.
-;; which-key shows in the minibuffer area → also stays readable.
+;; UI chrome (modeline, header-line) is PINNED to base size.
+;; Intermediate layers (which-key, minibuffer/vertico) scale at a
+;; reduced ratio so they remain readable at high zoom levels.
 ;;
-;; Step: ×1.5 per step (multiplicative, not additive).  From 14pt base:
+;; Step: ×1.5 per step (multiplicative).  From 14pt base:
 ;;   +1 ≈ 21pt    +2 ≈ 32pt    +3 ≈ 47pt
 ;;   +4 ≈ 71pt    +5 ≈ 106pt   +6 ≈ 159pt
 ;;
@@ -714,10 +714,10 @@ Skips past the TODO keyword and optional priority indicator [#A]."
 ;; SPC z 0         reset to default (saves level for restore)
 ;; SPC z z         restore zoom before last reset
 
-;; Base height: captured once at startup (reflects doom-font :size).
-;; Fallback to 140 = 14pt if face-attribute returns non-integer.
+;; --------------- state variables ---------------
+
 (defvar my/zoom-base-height 140
-  "Default face height before any zoom. Captured at Doom init.")
+  "Default face height before any zoom. Captured at Doom init (1/10 pt).")
 
 (defvar my/zoom-steps 0
   "Current zoom step count. 0 = default.")
@@ -725,13 +725,23 @@ Skips past the TODO keyword and optional priority indicator [#A]."
 (defvar my/zoom-saved-steps nil
   "Step count saved before last `my/zoom-reset', for `my/zoom-restore'.")
 
-;; Faces that must stay at base height (do not scale with text).
-;; These form the fixed UI chrome: status bar, minibuffer, tab bar.
+;; --------------- tuning knobs ---------------
+
+(defvar my/zoom-which-key-ratio 0.3
+  "Which-key font height as fraction of current default height.
+At 110pt default this gives ~33pt — readable but compact.")
+
+(defvar my/zoom-minibuffer-ratio 0.4
+  "Minibuffer font height as fraction of current default height.
+At 110pt default this gives ~44pt — readable for vertico candidates.")
+
+;; --------------- pinned UI faces (fixed at base) ---------------
+
 (defvar my/zoom-pinned-faces
   '(mode-line mode-line-inactive mode-line-active
-    minibuffer-prompt header-line
-    tab-bar tab-bar-tab tab-bar-tab-inactive)
-  "Faces pinned to `my/zoom-base-height' after every zoom operation.")
+    header-line tab-bar tab-bar-tab tab-bar-tab-inactive)
+  "Faces pinned to `my/zoom-base-height' after every zoom operation.
+Note: minibuffer-prompt is NOT here — it gets intermediate scaling.")
 
 (defun my/zoom-pin-ui ()
   "Set pinned UI faces to base height so they don't scale with text."
@@ -739,15 +749,100 @@ Skips past the TODO keyword and optional priority indicator [#A]."
     (when (facep face)
       (set-face-attribute face nil :height my/zoom-base-height))))
 
+;; --------------- which-key intermediate scaling ---------------
+
+(defvar my/zoom--which-key-cookie nil
+  "Face remap cookie for which-key buffer, so we can remove old remap.")
+
+(defun my/zoom--apply-which-key (new-height)
+  "Set which-key buffer face to intermediate size derived from NEW-HEIGHT."
+  (let* ((intermediate (max my/zoom-base-height
+                            (round (* new-height my/zoom-which-key-ratio))))
+         ;; Express as a ratio relative to the global default (new-height)
+         ;; because face-remap works relative to the buffer's inherited face.
+         (ratio (/ (float intermediate) new-height)))
+    (when-let ((buf (get-buffer " *which-key*")))
+      (with-current-buffer buf
+        (when my/zoom--which-key-cookie
+          (face-remap-remove-relative my/zoom--which-key-cookie))
+        (setq-local my/zoom--which-key-cookie
+                    (face-remap-add-relative 'default :height ratio))))))
+
+;; Hook: apply face remap whenever which-key creates/refreshes its buffer.
+(defun my/zoom--which-key-buffer-setup ()
+  "Apply intermediate font scaling when which-key buffer is initialized."
+  (when (and (string-prefix-p " *which-key*" (buffer-name))
+             (/= my/zoom-steps 0))
+    (let* ((current-h (face-attribute 'default :height nil t))
+           (intermediate (max my/zoom-base-height
+                              (round (* current-h my/zoom-which-key-ratio))))
+           (ratio (/ (float intermediate) current-h)))
+      (setq-local my/zoom--which-key-cookie
+                  (face-remap-add-relative 'default :height ratio)))))
+
+;; which-key-init-buffer-hook runs when the *which-key* buffer is set up
+(add-hook 'which-key-init-buffer-hook #'my/zoom--which-key-buffer-setup)
+
+;; --------------- minibuffer intermediate scaling ---------------
+
+(defun my/zoom-update-minibuffer ()
+  "Set minibuffer and echo area buffers to intermediate font size."
+  (let* ((current-h (face-attribute 'default :height nil t))
+         (intermediate (max my/zoom-base-height
+                            (round (* current-h my/zoom-minibuffer-ratio))))
+         (ratio (/ (float intermediate) current-h)))
+    (dolist (buf-name '(" *Minibuf-0*" " *Minibuf-1*"
+                        " *Echo Area 0*" " *Echo Area 1*"))
+      (when-let ((buf (get-buffer buf-name)))
+        (with-current-buffer buf
+          (setq-local face-remapping-alist
+                      `((default (:height ,ratio) default))))))))
+
+;; Hook: apply on every minibuffer entry (covers vertico, M-x, find-file).
+(defun my/zoom--minibuffer-setup ()
+  "Apply intermediate scaling to current minibuffer session."
+  (when (/= my/zoom-steps 0)
+    (let* ((current-h (face-attribute 'default :height nil t))
+           (intermediate (max my/zoom-base-height
+                              (round (* current-h my/zoom-minibuffer-ratio))))
+           (ratio (/ (float intermediate) current-h)))
+      (setq-local face-remapping-alist
+                  `((default (:height ,ratio) default))))))
+
+(add-hook 'minibuffer-setup-hook #'my/zoom--minibuffer-setup)
+
+;; --------------- corfu popup refresh ---------------
+
+(defun my/zoom--invalidate-corfu ()
+  "Hide corfu popup so it re-creates with new font on next completion."
+  (when (and (fboundp 'corfu-quit) (fboundp 'corfu--popup-hide))
+    (ignore-errors (corfu--popup-hide))))
+
+;; --------------- core zoom engine ---------------
+
 (defun my/zoom--apply (steps)
-  "Set global default face to base × 1.5^STEPS and re-pin UI faces."
+  "Set global default face to base × 1.5^STEPS and update all UI layers."
   (let ((new-h (max 80 (round (* my/zoom-base-height (expt 1.5 steps))))))
+    ;; 1. Global default face — affects all buffer content
     (set-face-attribute 'default nil :height new-h)
+
+    ;; 2. Pin modeline/header-line at base size
     (my/zoom-pin-ui)
+
+    ;; 3. Which-key — intermediate font
+    (my/zoom--apply-which-key new-h)
+
+    ;; 4. Minibuffer/echo area — intermediate font
+    (my/zoom-update-minibuffer)
+
+    ;; 5. Corfu — force re-create on next completion
+    (my/zoom--invalidate-corfu)
+
     (message "Zoom %+d  ×%.2f  ≈%dpt"
              steps (expt 1.5 steps) (/ new-h 10))))
 
-;; Capture base height after Doom finishes font setup.
+;; --------------- init: capture base height ---------------
+
 (add-hook 'doom-after-init-hook
   (lambda ()
     (let ((h (face-attribute 'default :height nil t)))
@@ -757,6 +852,8 @@ Skips past the TODO keyword and optional priority indicator [#A]."
 ;; Re-pin UI faces after any theme reload (Doom resets faces on theme change).
 (add-hook 'doom-load-theme-hook #'my/zoom-pin-ui)
 
+;; --------------- interactive commands ---------------
+
 (defun my/zoom-in ()
   "Zoom in one step (×1.5) — all buffers, help, menus, everything."
   (interactive)
@@ -788,6 +885,8 @@ Skips past the TODO keyword and optional priority indicator [#A]."
     (setq my/zoom-steps my/zoom-saved-steps
           my/zoom-saved-steps nil)))
 
+;; --------------- keybindings ---------------
+
 (map! :leader
       (:prefix ("z" . "zoom")
        :desc "Zoom in  (×1.5)"     "+" #'my/zoom-in