feat(nov): reading-view theme layer with palettes and font sizing

EPUB reading prefs were scattered: a hardcoded Merriweather/180 font-remap in calibredb-epub-config's nov hook, no color control (the old sepia foreground had been stripped), and a frame-global EBook fontaine preset as the only way to size up. That preset resized the font in every buffer in the frame, not just the book.

I pulled the reading view into its own layer, modules/nov-reading.el, on top of stock nov (no fork). It owns three things, all buffer-local: a reading palette (sepia/dark/light, each a face the dupre theme owns, sepia the default), the serif typography (family plus a defcustom base height replacing the hardcoded 180), and page font sizing (+/- bump the size live, = resets to the base). Width moves to { }. calibredb-epub-config keeps the library and width/centering layout. Its nov hook now calls into the layer.

The three palette faces register as a nov-reading app in theme-studio (face_data.py), so they're tunable there like any other app. I dropped the EBook fontaine preset, since reading size is buffer-local now.

2 files changed, 66 insertions, 5 deletions

diff --git a/tests/test-calibredb-epub-config.el b/tests/test-calibredb-epub-config.el
index cb3a9ba74..71581d4c9 100644
--- a/tests/test-calibredb-epub-config.el
+++ b/tests/test-calibredb-epub-config.el
@@ -173,12 +173,13 @@ re-render of the document."
   (should (commandp #'cj/nov-narrow-text)))
 
 (ert-deftest test-calibredb-epub-nov-width-commands-bound-in-nov-mode-map ()
-  "Normal: +/= widen and -/_ narrow the text column in `nov-mode-map'."
+  "Normal: { } adjust the text column in `nov-mode-map' (+/-/= are font size)."
   (skip-unless (and (require 'nov nil t) (boundp 'nov-mode-map)))
-  (should (eq (keymap-lookup nov-mode-map "+") #'cj/nov-widen-text))
-  (should (eq (keymap-lookup nov-mode-map "=") #'cj/nov-widen-text))
-  (should (eq (keymap-lookup nov-mode-map "-") #'cj/nov-narrow-text))
-  (should (eq (keymap-lookup nov-mode-map "_") #'cj/nov-narrow-text)))
+  (should (eq (keymap-lookup nov-mode-map "}") #'cj/nov-widen-text))
+  (should (eq (keymap-lookup nov-mode-map "{") #'cj/nov-narrow-text))
+  (should (eq (keymap-lookup nov-mode-map "+") #'cj/nov-reading-text-bigger))
+  (should (eq (keymap-lookup nov-mode-map "-") #'cj/nov-reading-text-smaller))
+  (should (eq (keymap-lookup nov-mode-map "=") #'cj/nov-reading-text-reset)))
 
 ;;; -------------------------- cj/nov-apply-preferences ------------------------
 
diff --git a/tests/test-nov-reading--palette.el b/tests/test-nov-reading--palette.el
new file mode 100644
index 000000000..164ec75f4
--- /dev/null
+++ b/tests/test-nov-reading--palette.el
@@ -0,0 +1,60 @@
+;;; test-nov-reading--palette.el --- nov reading-palette tests -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Pure-logic tests for the nov-mode reading-palette selector: name->face
+;; resolution and the cycle order (palettes, then the no-palette state, wrapping).
+;; The buffer-local face-remap application is exercised live, not here.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'nov-reading)
+
+(declare-function cj/nov--reading-palette-face "nov-reading" (name))
+(declare-function cj/nov--next-reading-palette "nov-reading" (current names))
+(defvar cj/nov-reading-palettes)
+
+;;; ----------------------- cj/nov--reading-palette-face -----------------------
+
+(ert-deftest test-nov-reading-palette-face-known ()
+  "Normal: a known palette name resolves to its face."
+  (let ((cj/nov-reading-palettes '(("sepia" . cj/nov-reading-sepia)
+                                   ("dark"  . cj/nov-reading-dark))))
+    (should (eq (cj/nov--reading-palette-face "sepia") 'cj/nov-reading-sepia))
+    (should (eq (cj/nov--reading-palette-face "dark") 'cj/nov-reading-dark))))
+
+(ert-deftest test-nov-reading-palette-face-unknown ()
+  "Error: an unknown name resolves to nil."
+  (let ((cj/nov-reading-palettes '(("sepia" . cj/nov-reading-sepia))))
+    (should-not (cj/nov--reading-palette-face "nope"))))
+
+(ert-deftest test-nov-reading-palette-face-nil ()
+  "Boundary: a nil name resolves to nil."
+  (let ((cj/nov-reading-palettes '(("sepia" . cj/nov-reading-sepia))))
+    (should-not (cj/nov--reading-palette-face nil))))
+
+;;; ----------------------- cj/nov--next-reading-palette -----------------------
+
+(ert-deftest test-nov-reading-next-palette-advances ()
+  "Normal: cycles to the next palette in order."
+  (should (equal (cj/nov--next-reading-palette "sepia" '("sepia" "dark" "light"))
+                 "dark")))
+
+(ert-deftest test-nov-reading-next-palette-last-to-none ()
+  "Boundary: the last palette cycles to the no-palette state (nil)."
+  (should-not (cj/nov--next-reading-palette "light" '("sepia" "dark" "light"))))
+
+(ert-deftest test-nov-reading-next-palette-none-to-first ()
+  "Boundary: the no-palette state (nil) cycles to the first palette."
+  (should (equal (cj/nov--next-reading-palette nil '("sepia" "dark" "light"))
+                 "sepia")))
+
+(ert-deftest test-nov-reading-next-palette-unknown-current-falls-to-first ()
+  "Error: an unknown current palette falls back to the first."
+  (should (equal (cj/nov--next-reading-palette "gone" '("sepia" "dark" "light"))
+                 "sepia")))
+
+(provide 'test-nov-reading--palette)
+;;; test-nov-reading--palette.el ends here