feat: bundle Luciole, Literata, Charis SIL and a Hebrew fallback face

app/lib/application/controllers/reader_settings_controller.dart

@@ -1,6 +1,7 @@
 import 'package:signals/signals.dart';
 
 import '../../database/database.dart';
+import '../fonts.dart';
 
 /// The reader's presentation choices (spec 8.2) plus the per-app limits they
 /// move within. Values persist through ReaderSettings in the database.
@@ -19,7 +20,7 @@ class ReaderSettingsController {
   static const themeModes = ['light', 'dark', 'system'];
   static const variants = ['site', 'warm', 'cool', 'green', 'mono'];
 
-  final font = signal('Atkinson Hyperlegible');
+  final font = signal(defaultFontFamily);
   final fontScale = signal(1.0);
   final themeMode = signal('system');
   final variant = signal('site');
@@ -34,7 +35,11 @@ class ReaderSettingsController {
   }
 
   Future<bool> setFont(String family) async {
-    if (family.isEmpty || family == font.value) return false;
+    // Only a family this build bundles: an unknown one would silently render
+    // in the platform's font instead.
+    if (!readerFonts.any((f) => f.family == family) || family == font.value) {
+      return false;
+    }
     font.value = family;
     await _persist();
     return true;

app/lib/application/fonts.dart

@@ -0,0 +1,60 @@
+/// The typefaces bundled with the client (spec 8.2: the reader chooses).
+/// Pure data, shared by the settings page that offers them and the renderer
+/// that applies them.
+library;
+
+/// One bundled family: the name used in pubspec.yaml and stored in settings,
+/// the id of its display name in the locale file, and where to look when it
+/// has no glyph for a character.
+typedef ReaderFont = ({String family, String labelId, List<String> fallback});
+
+/// Offered in this order: the two sans faces first, then the two serifs.
+/// Adding a font is four files in assets/fonts, one `fonts` entry in
+/// pubspec.yaml, one entry here, one label in the locale file, and its licence
+/// beside the files.
+///
+/// Each face names where to look for a character it has no glyph for. Hebrew
+/// comes from a bundled Hebrew face, matched to the shape of the chosen one,
+/// so it never depends on what the device happens to have installed. The
+/// serifs also cover Greek, Cyrillic and a wide Latin range, so each falls
+/// back to the other; the sans faces are narrow and have no bundled sans to
+/// turn to, so for those the platform answers, and it answers a sans with a
+/// sans. Scripts nothing here covers, such as Arabic and the CJK languages,
+/// always come from the platform.
+const readerFonts = <ReaderFont>[
+  (
+    family: 'Atkinson Hyperlegible',
+    labelId: 'settings-font-atkinson',
+    fallback: [hebrewSans],
+  ),
+  (
+    family: 'Luciole',
+    labelId: 'settings-font-luciole',
+    fallback: [hebrewSans],
+  ),
+  (
+    family: 'Literata',
+    labelId: 'settings-font-literata',
+    fallback: ['Charis SIL', hebrewSerif],
+  ),
+  (
+    family: 'Charis SIL',
+    labelId: 'settings-font-charis',
+    fallback: ['Literata', hebrewSerif],
+  ),
+];
+
+/// Bundled to be fallen back on, never offered: the reader picks a face for
+/// the Latin text they are reading, and Hebrew follows its shape.
+const hebrewSans = 'Noto Sans Hebrew';
+const hebrewSerif = 'Noto Serif Hebrew';
+
+const defaultFontFamily = 'Atkinson Hyperlegible';
+
+/// Where to look after [family], or nothing when it is not one of ours.
+List<String> fallbackFor(String family) {
+  for (final font in readerFonts) {
+    if (font.family == family) return font.fallback;
+  }
+  return const [];
+}

app/lib/application/pages/settings_page.dart

@@ -1,17 +1,11 @@
 import '../../l10n/strings.dart';
 import '../../mews/document.dart';
+import '../fonts.dart';
 import '../controllers/reader_settings_controller.dart'
     show ReaderSettingsController;
 import 'mews_urls.dart';
 import 'page_blocks.dart';
 
-/// The bundled typefaces the reader can pick. Adding a font is one TTF in
-/// assets/fonts, one entry in pubspec.yaml, one entry here and one label in
-/// the locale file.
-const _fonts = <({String family, String labelId})>[
-  (family: 'Atkinson Hyperlegible', labelId: 'settings-font-atkinson'),
-];
-
 /// Message ids for the values the controller accepts. Kept literal so every
 /// id in the locale file can be found by searching for it.
 const _themeLabels = {
@@ -43,7 +37,7 @@ Future<MewsPage> buildSettingsPage(
       ...chrome(title: title, current: url, strings: strings),
       HeadingBlock(2, [MewsText(strings.t('settings-font-heading'))]),
       choiceRow([
-        for (final font in _fonts)
+        for (final font in readerFonts)
           (
             href: MewsUrls.action('set-font', {'value': font.family}),
             label: strings.t(font.labelId),

app/lib/presentation/app.dart

@@ -9,6 +9,7 @@ import '../application/controllers/bookmarks_controller.dart';
 import '../application/controllers/browser_controller.dart';
 import '../application/controllers/reader_settings_controller.dart';
 import '../application/controllers/subscriptions_controller.dart';
+import '../application/fonts.dart';
 import '../application/internal_actions.dart';
 import '../application/internal_pages.dart';
 import '../database/database.dart';
@@ -171,6 +172,7 @@ class _ThemedApp extends StatelessWidget {
       // The chrome reads in the typeface the reader chose for pages, so the
       // address bar and the page below it are not two different faces.
       fontFamily: fontFamily,
+      fontFamilyFallback: fallbackFor(fontFamily),
       scaffoldBackgroundColor: palette.background,
       // Selection highlights and the caret follow the palette too.
       textSelectionTheme: TextSelectionThemeData(

app/lib/presentation/reader/mews_page_view.dart

@@ -4,6 +4,7 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 
 import '../../l10n/strings.dart';
+import '../../application/fonts.dart';
 import '../../mews/document.dart';
 import 'palettes.dart';
 
@@ -117,6 +118,7 @@ class _MewsPageViewState extends State<MewsPageView> {
           style: TextStyle(
             color: palette.foreground.withValues(alpha: 0.7),
             fontFamily: widget.fontFamily,
+            fontFamilyFallback: fallbackFor(widget.fontFamily),
             fontSize: base * 0.85,
           ),
         ),
@@ -129,6 +131,7 @@ class _MewsPageViewState extends State<MewsPageView> {
     final foreground = TextStyle(
       color: palette.foreground,
       fontFamily: widget.fontFamily,
+      fontFamilyFallback: fallbackFor(widget.fontFamily),
       fontSize: base,
       height: 1.5,
     );