From efc1b1101a524c6a23bcb8ba828b3cf36c81040c Mon Sep 17 00:00:00 2001
From: Craig Jennings <c@cjennings.net>
Date: Fri, 3 Jul 2026 05:22:57 -0400
Subject: fix(modeline): pin padding height to the frame, not the buffer

The leading modeline space set its height with a display (height 1.15) property, which scales against the buffer's default face. nov-mode's reading view remaps default to 18pt, so there the padding grew to 1.15x that and the bar rendered far taller than normal. The theme's absolute mode-line height couldn't help, since the padding space drives the strip height, not the face.

The padding now uses an absolute integer height anchored to the frame's default face, so a buffer that enlarges its own default (nov, text-scale) no longer inflates the bar. Normal buffers are unchanged, and the nov bar matches them.
---
 modules/modeline-config.el             | 19 +++++++++++++------
 tests/test-modeline-config-segments.el | 26 +++++++++++++++++---------
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/modules/modeline-config.el b/modules/modeline-config.el
index be7f72e5..6ba6efca 100644
--- a/modules/modeline-config.el
+++ b/modules/modeline-config.el
@@ -126,12 +126,19 @@ kills the buffer-local value so the default format returns."
 
 (defun cj/--modeline-padding ()
   "Return the leading modeline space, taller per `cj/modeline-height-factor'.
-A display height property on a single space pads the whole modeline
-vertically without touching the mode-line faces the theme owns."
-  (if (and cj/modeline-height-factor
-           (/= cj/modeline-height-factor 1.0))
-      (propertize " " 'display `(height ,cj/modeline-height-factor))
-    " "))
+An absolute :height face on a single space pads the whole modeline
+vertically.  The height is anchored to the frame's default face rather
+than the current buffer's, so a buffer that remaps `default' larger —
+nov-mode's reading view, `text-scale-mode' — no longer inflates the bar.
+A `display (height FACTOR)' property would scale with the buffer's default
+face and blow the modeline up in those buffers."
+  (let ((base (face-attribute 'default :height nil t)))
+    (if (and cj/modeline-height-factor
+             (/= cj/modeline-height-factor 1.0)
+             (integerp base))
+        (propertize " " 'face
+                    (list :height (round (* cj/modeline-height-factor base))))
+      " ")))
 
 (defvar-local cj/--modeline-mode-icon-cache nil
   "Cons of (MAJOR-MODE . GRAPHIC-P) paired with the rendered mode segment.
diff --git a/tests/test-modeline-config-segments.el b/tests/test-modeline-config-segments.el
index 580a7711..0245749d 100644
--- a/tests/test-modeline-config-segments.el
+++ b/tests/test-modeline-config-segments.el
@@ -104,19 +104,27 @@
 
 ;; ------------------------------- Padding --------------------------------------
 
-(ert-deftest test-modeline-config-padding-carries-height-display ()
-  "Normal: padding space carries a display height property."
+(ert-deftest test-modeline-config-padding-absolute-height-face ()
+  "Normal: padding space carries a face with an absolute integer :height.
+The height is anchored to the frame default (not the current buffer's
+`default'), so a buffer that remaps `default' larger — nov's reading view,
+`text-scale-mode' — no longer inflates the modeline."
   (let ((cj/modeline-height-factor 1.2))
-    (let ((s (cj/--modeline-padding)))
+    (let* ((s (cj/--modeline-padding))
+           (face (get-text-property 0 'face s))
+           (h (plist-get face :height)))
       (should (stringp s))
-      (should (get-text-property 0 'display s)))))
+      (should (integerp h))
+      (should (= h (round (* 1.2 (face-attribute 'default :height nil t))))))))
 
 (ert-deftest test-modeline-config-padding-plain-at-factor-one ()
-  "Boundary: factor 1.0 (or nil) yields a plain space, no display prop."
-  (let ((cj/modeline-height-factor 1.0))
-    (let ((s (cj/--modeline-padding)))
-      (should (stringp s))
-      (should-not (get-text-property 0 'display s)))))
+  "Boundary: factor 1.0 (or nil) yields a plain space, no height styling."
+  (dolist (factor (list 1.0 nil))
+    (let ((cj/modeline-height-factor factor))
+      (let ((s (cj/--modeline-padding)))
+        (should (stringp s))
+        (should-not (get-text-property 0 'display s))
+        (should-not (get-text-property 0 'face s))))))
 
 (provide 'test-modeline-config-segments)
 ;;; test-modeline-config-segments.el ends here
-- 
cgit v1.2.3