fix(ui): draw non-Latin file names in the window caption (#840)

The painted title uses a Latin-only face, so names in other scripts were shown as question marks. A covering fallback face is now loaded for the caption.

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>

ROADMAP.md

@@ -2,7 +2,7 @@
 
 **Stage: alpha** · next: beta, ~15 points (60% → 75% ready for real work) and ~150–230 h away
 
-> **Last reviewed:** 2026-10-12 · **Last updated:** 2026-10-12 · **Change:** trivial (32-bit Windows starts on OpenGL so launch no longer exits; previously trivial: every measurement follows the Options unit, #755; previously trivial: Insert › SmartArt landed, #497: catalog 429/451 → 437/458 (95.4%); previously trivial: Turkish interface landed; previously trivial: formatting revisions landed, #41; previously trivial: Draw tab ink, #307, and Draw Table and Eraser, #303, landed: catalog 402/434; previously minor: readiness table with hours per audience; full number back to the additive weighted sum, 60%; mainstream and essentials numbers added; alpha gate checked; previously major: full re-measure against Word for Mac 16.113.4; restructured to the craftrules progress-docs standard) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4
+> **Last reviewed:** 2026-10-12 · **Last updated:** 2026-10-12 · **Change:** trivial (non-Latin file names in the window caption; previously trivial: every measurement follows the Options unit, #755; previously trivial: Insert › SmartArt landed, #497: catalog 429/451 → 437/458 (95.4%); previously trivial: Turkish interface landed; previously trivial: formatting revisions landed, #41; previously trivial: Draw tab ink, #307, and Draw Table and Eraser, #303, landed: catalog 402/434; previously minor: readiness table with hours per audience; full number back to the additive weighted sum, 60%; mainstream and essentials numbers added; alpha gate checked; previously major: full re-measure against Word for Mac 16.113.4; restructured to the craftrules progress-docs standard) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4
 
 WordCraft aims for complete parity with Microsoft Word, then goes further on speed, openness and
 agent control. This page is the summary; the assessment is
@@ -132,6 +132,7 @@ Ranked, to beta (detail and remaining milestones in [docs/roadmap.md](docs/roadm
 ## Progress log
 
 | Date | What landed |
+| 2026-10-12 | Window caption: a non-Latin file name is drawn with a document fallback face (or the CJK UI font), instead of `?` |
 | 2026-10-12 | 32-bit Windows starts on OpenGL. DirectX 12 graphics pipeline creation returns "The parameter is incorrect" and the app exited before the window appeared |
 | 2026-10-12 | New documents follow the system region (#838): A4 and centimetres outside the US (Letter in the CLDR Letter territories, inches in the US), lengths written with the region's decimal separator (`2,54 cm`) and typed with either; an explicit Measurement units choice wins; `file.options {"region"}` for agents |
 | 2026-10-12 | Paste from other programs keeps their formatting (#687): Ctrl+V and Home › Paste read the system clipboard's HTML (and RTF on Windows and Wayland); Merge Formatting takes the destination's font and paragraph and keeps bold, italic, underline and strikethrough; Paste Special lists what the system clipboard holds (HTML, RTF, picture, text). Linux: pictures copied in a browser or Spectacle paste on KDE and other Wayland desktops (data-control clipboard), and a paste that finds nothing usable names what the clipboard holds instead of "empty" (#833) |

crates/ui-egui/src/canvas.rs

@@ -66,7 +66,8 @@ pub struct CanvasState {
     pub focused: bool,
     pub render_ms: f64,
     pub ime_preedit: String,
-    /// Document faces added to the interface fonts to draw the input method's composition (#565).
+    /// Document faces added to the interface fonts so the input method's composition (#565) and a
+    /// file name in the window caption can be drawn.
     pub(crate) ime_faces: Vec<std::sync::Arc<wordcraft_fonts::FontFace>>,
     pub want_focus: bool,
     pub context_issue: Option<serde_json::Value>,

crates/ui-egui/src/lib.rs

@@ -1230,6 +1230,25 @@ impl WordApp {
         }
     }
 
+    /// The window caption is painted with the semibold interface face (Inter). A file name in a
+    /// script those faces lack would otherwise be drawn as `?`. Borrow the document fonts'
+    /// fallback faces, as IME composition does (#565). A CJK name uses the CJK UI font instead:
+    /// those collections are too large to add here.
+    fn ensure_caption_fonts(&mut self) {
+        let stem = self.title_stem();
+        if stem.chars().any(wordcraft_fonts::is_cjk) {
+            self.want_system_cjk = true;
+        }
+        let new = theme::faces_for_preedit(&stem, &self.canvas.ime_faces, theme::caption_char_covered, |c| {
+            wordcraft_fonts::FontDb::global().fallback_for(c, u32::MAX)
+        });
+        if !new.is_empty() {
+            self.canvas.ime_faces.extend(new);
+            // Fonts are already installed for this frame's language; load the new faces too.
+            self.styled = false;
+        }
+    }
+
     /// Document title for the title bar (and the suggested file name). An untitled document is
     /// named in the interface language, as `Document1` is in English.
     pub fn title_stem(&self) -> String {
@@ -1257,18 +1276,11 @@ impl WordApp {
         }
         options::sync(self);
         // Chinese text wants the Chinese face before the Japanese one (one glyph style per line).
-        // An installed CJK font is read only once CJK text is shown (#241): never for an English
-        // interface that doesn't open the language list.
-        let system_cjk = self.fonts_system_cjk || self.want_system_cjk || lang.uses_cjk();
-        if !self.styled || lang.prefers_hans() != self.fonts_hans || system_cjk != self.fonts_system_cjk {
-            theme::install_fonts_extra(ctx, lang.prefers_hans(), system_cjk, &self.canvas.ime_faces);
-            self.fonts_hans = lang.prefers_hans();
-            self.fonts_system_cjk = system_cjk;
-            // Mod with -, = and 0 are Word shortcuts (optional hyphen, subscript, paragraph spacing);
-            // egui's keyboard zoom would also scale the whole window on them. Zoom is View › Zoom.
-            ctx.options_mut(|o| o.zoom_with_keyboard = false);
-            self.styled = true;
-        }
+        // An installed CJK font is read only once CJK text is shown (#241): a CJK interface, the
+        // language names in Options, or a file name the caption is drawing. A file opened later
+        // in this frame (dialog, drop, control channel) is picked up again at the end.
+        self.ensure_caption_fonts();
+        self.install_ui_fonts(ctx, lang);
         if let Some(answer) = self.desktop_theme.take_change() {
             self.desktop_dark = Some(answer);
         }
@@ -1341,9 +1353,27 @@ impl WordApp {
                 };
             }
         }
+        // The open above may have changed the file name the caption draws.
+        self.ensure_caption_fonts();
+        self.install_ui_fonts(ctx, lang);
         self.report_dirty();
     }
 
+    /// Install the interface fonts when the language, the CJK fallback, or a caption fallback
+    /// face has changed since the last install.
+    fn install_ui_fonts(&mut self, ctx: &egui::Context, lang: i18n::Lang) {
+        let system_cjk = self.fonts_system_cjk || self.want_system_cjk || lang.uses_cjk();
+        if !self.styled || lang.prefers_hans() != self.fonts_hans || system_cjk != self.fonts_system_cjk {
+            theme::install_fonts_extra(ctx, lang.prefers_hans(), system_cjk, &self.canvas.ime_faces);
+            self.fonts_hans = lang.prefers_hans();
+            self.fonts_system_cjk = system_cjk;
+            // Mod with -, = and 0 are Word shortcuts (optional hyphen, subscript, paragraph spacing);
+            // egui's keyboard zoom would also scale the whole window on them. Zoom is View › Zoom.
+            ctx.options_mut(|o| o.zoom_with_keyboard = false);
+            self.styled = true;
+        }
+    }
+
     /// Tell the host whether the document has unsaved changes ([`Services::on_dirty`]).
     fn report_dirty(&self) {
         if let Some(f) = &self.services.on_dirty {
@@ -1772,6 +1802,39 @@ mod tests {
         assert_eq!(titles(&mut app), 1);
     }
 
+    /// The caption is Inter semibold, which has no Hebrew (or Arabic, Thai, …), so egui would
+    /// paint each of those letters as `?`. Opening such a file borrows one document fallback
+    /// face. A CJK name uses the CJK UI font instead of that list.
+    #[test]
+    fn non_latin_file_name_is_drawn_in_the_caption() {
+        let ctx = egui::Context::default();
+        let frame = |app: &mut WordApp| {
+            ctx.run_ui(egui::RawInput::default(), |ui| app.logic(ui.ctx())).drop_without_applying_deltas();
+        };
+        let mut latin = app();
+        latin.session.path = Some("report.docx".into());
+        frame(&mut latin);
+        assert!(!latin.want_system_cjk);
+        assert!(latin.canvas.ime_faces.is_empty(), "a Latin name needs no extra face");
+
+        let mut hebrew = app();
+        hebrew.session.path = Some("מסמך.docx".into());
+        frame(&mut hebrew);
+        let letter = 'מ';
+        if wordcraft_fonts::FontDb::global().fallback_for(letter, u32::MAX).is_some_and(|f| f.data().len() <= 16 << 20) {
+            assert!(hebrew.canvas.ime_faces.iter().any(|f| f.covers(letter)), "the caption borrows a face that covers the file name");
+        }
+        let n = hebrew.canvas.ime_faces.len();
+        frame(&mut hebrew);
+        assert_eq!(hebrew.canvas.ime_faces.len(), n, "the face is added once");
+
+        let mut cjk = app();
+        cjk.session.path = Some("文档.docx".into());
+        frame(&mut cjk);
+        assert!(cjk.want_system_cjk, "a CJK file name loads the CJK UI font");
+        assert!(cjk.canvas.ime_faces.is_empty(), "CJK collections are not copied into the fallback list");
+    }
+
     fn app() -> WordApp {
         WordApp::new(Session::new(wordcraft_doc::Document::new()), Services::default())
     }

crates/ui-egui/src/theme.rs

@@ -346,7 +346,8 @@ pub fn install_fonts_with(ctx: &egui::Context, prefer_hans: bool, system_cjk: bo
 }
 
 /// [`install_fonts_with`], also adding document-font `faces` as last-resort fallbacks (#565): the
-/// faces that cover the text an input method is composing.
+/// faces that cover text the interface fonts cannot draw (an input method's composition, or a
+/// file name in the window caption).
 pub fn install_fonts_extra(ctx: &egui::Context, prefer_hans: bool, system_cjk: bool, faces: &[Arc<wordcraft_fonts::FontFace>]) {
     let mut fonts = font_definitions(prefer_hans, system_cjk);
     add_fallback_faces(&mut fonts, faces);
@@ -368,10 +369,17 @@ pub fn add_fallback_faces(fonts: &mut FontDefinitions, faces: &[Arc<wordcraft_fo
     }
 }
 
-/// Document faces needed to draw `text` (the input method's composition), one for each character
-/// the interface fonts cannot draw, skipping faces in `have` (#565). Characters of the embedded
-/// interface fonts are not looked up; very large faces (system CJK collections) are left to the CJK
-/// fallback.
+/// A character the window caption can already draw without a document fallback: the Latin range
+/// the interface faces cover, or CJK, which uses the CJK UI font ([`install_fonts_with`]) rather
+/// than a document face. System CJK collections are larger than [`faces_for_preedit`] will load.
+pub fn caption_char_covered(c: char) -> bool {
+    (c as u32) < 0x250 || wordcraft_fonts::is_cjk(c)
+}
+
+/// Document faces needed to draw `text` (the input method's composition, or a file name in the
+/// window caption), one for each character the interface fonts cannot draw, skipping faces in
+/// `have` (#565). Characters of the embedded interface fonts are not looked up; very large faces
+/// (system CJK collections) are left to the CJK fallback.
 pub fn faces_for_preedit(
     text: &str,
     have: &[Arc<wordcraft_fonts::FontFace>],
@@ -689,6 +697,29 @@ mod tests {
         assert!(defs.families[&egui::FontFamily::Proportional].last().is_some_and(|n| n.starts_with("fallback ")));
     }
 
+    /// A file name in a script Inter lacks (Hebrew, Arabic, …) is drawn in the window caption,
+    /// which uses the semibold face. egui paints a missing glyph as `?`, so the caption borrows
+    /// one document fallback face. CJK stays with the CJK UI font: those files are too large to
+    /// add here.
+    #[test]
+    fn caption_borrows_one_fallback_face_for_hebrew() {
+        let face = wordcraft_fonts::FontDb::global().face("Source Sans 3", "Regular");
+        let lookup = |c: char| {
+            assert!(!super::caption_char_covered(c), "{c} is already drawn by the interface fonts");
+            Some(face.clone())
+        };
+        let hebrew = "מסמך";
+        let got = super::faces_for_preedit(hebrew, &[], super::caption_char_covered, lookup);
+        assert_eq!(got.len(), 1, "one face for the whole file name");
+        assert!(super::faces_for_preedit(hebrew, &got, super::caption_char_covered, lookup).is_empty(), "already added");
+        assert!(super::faces_for_preedit("文档", &[], super::caption_char_covered, lookup).is_empty(), "CJK uses the CJK UI font");
+        assert!(super::faces_for_preedit("report", &[], super::caption_char_covered, lookup).is_empty(), "Latin needs nothing");
+        let mut defs = super::font_definitions(false, false);
+        super::add_fallback_faces(&mut defs, &got);
+        let semi = &defs.families[&egui::FontFamily::Name("semibold".into())];
+        assert!(semi.iter().any(|n| n.starts_with("fallback ")), "the caption is painted with semibold");
+    }
+
     /// #656: dialog primary buttons, the Discord pill, the table eraser and the Navigation search
     /// highlight take their colours from the theme, not fixed light-theme values.
     #[test]

docs/ui-parity.md

@@ -1,6 +1,6 @@
 # UI parity with Microsoft Word
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** trivial (Navigation headings truncate in the resizable pane, #759; previously trivial: Find and Replace special characters and wildcards, #543; previously trivial: Customize Ribbon and the Quick Access Toolbar, #379; previously: major, first version; ribbon, dialogs, shortcuts and on-canvas interaction measured from `crates/ui-egui` and the command registry) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** trivial (a non-Latin file name in the window caption is drawn with a fallback face instead of `?`; previously trivial: every measurement follows the Options unit, #755; previously trivial: Find and Replace special characters and wildcards, #543; previously trivial: Customize Ribbon and the Quick Access Toolbar, #379; previously: major, first version; ribbon, dialogs, shortcuts and on-canvas interaction measured from `crates/ui-egui` and the command registry) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4
 
 How WordCraft looks and feels next to Word: ribbon, dialogs, panes, keyboard, mouse and touch.
 Typing behaviour has its own checklist ([`typing-parity.md`](typing-parity.md)). All assets are our
@@ -44,6 +44,7 @@ own (`AGENTS.md`: no Microsoft iconography, ever).
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-12 | trivial | Window caption: a file name in a script the interface fonts lack (Hebrew, Arabic, and the rest; CJK via the CJK UI font) is drawn with a fallback face instead of `?` |
 | 2026-10-12 | trivial | Navigation headings truncate with an ellipsis within the pane width, preserving resizing and full-text hover (#759) |
 | 2026-10-11 | minor | Reading Mode: viewport-height horizontal columns, animated paging, transient display controls, heading navigation and responsive anchored resizing |
 | 2026-10-11 | trivial | Alt activation handles native key/modifier events in either order, including key-up with the old Alt flag; taps toggle once, chords and focus loss do not activate KeyTips |