Fonts: a Bidi theme slot names the theme's complex-script font (#1619)

w:asciiTheme="minorBidi" (and majorBidi, and w:cstheme) read as the
theme's Latin font, so a template's titles came out in Calibri where
Word draws Arial. Measured in Word: the slot names the theme's a:cs
font, and an empty a:cs names nothing, so the font inherited from the
style applies.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>

crates/docx/src/read/mod.rs

@@ -726,6 +726,9 @@ impl Reader<'_> {
             if let Some(f) = face("a:minorFont") {
                 self.doc.settings.minor_font = f;
             }
+            let cs = |n: &str| fs.child(n).and_then(|f| f.child("a:cs")).and_then(|c| c.attr("typeface")).unwrap_or_default().to_string();
+            self.pc.major_cs = cs("a:majorFont");
+            self.pc.minor_cs = cs("a:minorFont");
         }
         self.pc.major_font = self.doc.settings.major_font.clone();
         self.pc.minor_font = self.doc.settings.minor_font.clone();

crates/docx/src/read/props.rs

@@ -43,6 +43,9 @@ use crate::xml::El;
 pub struct PropCtx {
     pub major_font: String,
     pub minor_font: String,
+    /// The theme's complex-script fonts (`a:cs`), which the `…Bidi` theme slots name.
+    pub major_cs: String,
+    pub minor_cs: String,
     /// The theme's colour scheme (dk1, lt1, dk2, lt2, accent1..6, hlink, folHlink); empty when the
     /// package has none, and then `w:themeColor` falls back to the fixed colour.
     pub theme_colors: Vec<Rgb>,
@@ -82,7 +85,10 @@ impl PropCtx {
     }
 
     fn theme_font(&self, t: &str) -> Option<String> {
-        let f = if t.starts_with("major") { &self.major_font } else { &self.minor_font };
+        let (latin, cs) = if t.starts_with("major") { (&self.major_font, &self.major_cs) } else { (&self.minor_font, &self.minor_cs) };
+        // Measured in Word: `minorBidi`/`majorBidi` name the complex-script font, and an empty one
+        // names nothing, so the font beside it or the inherited one applies.
+        let f = if t.ends_with("Bidi") { cs } else { latin };
         (!f.is_empty()).then(|| f.clone())
     }
 

crates/docx/tests/fixtures.rs

@@ -2567,6 +2567,23 @@ fn text_frames_read_and_round_trip() {
     assert!(q.iter().any(|x| x.props.drop_cap == Some(2) && x.props.frame.is_none()));
 }
 
+/// Measured in Word: `w:asciiTheme="minorBidi"` names the theme's complex-script font (`a:cs`);
+/// when that is empty it names nothing, and the run keeps the font it inherits.
+#[test]
+fn bidi_theme_slots_name_the_complex_script_font() {
+    let font = |cs: &str| {
+        let theme = format!(
+            r#"<?xml version="1.0" encoding="UTF-8" standalone="yes"?><a:theme xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" name="T"><a:themeElements><a:fontScheme name="F"><a:majorFont><a:latin typeface="Cambria"/><a:ea typeface=""/><a:cs typeface="{cs}"/></a:majorFont><a:minorFont><a:latin typeface="Calibri"/><a:ea typeface=""/><a:cs typeface="{cs}"/></a:minorFont></a:fontScheme></a:themeElements></a:theme>"#
+        );
+        let rels = [("rId9", "http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme", "theme/theme1.xml")];
+        let body = r#"<w:p><w:r><w:rPr><w:rFonts w:asciiTheme="minorBidi" w:hAnsiTheme="minorBidi"/></w:rPr><w:t>x</w:t></w:r></w:p>"#;
+        let d = wordcraft_docx::read(&docx(body, &rels, &[("word/theme/theme1.xml", &theme)])).unwrap();
+        paras(&d)[0].runs[0].props.font.clone()
+    };
+    assert_eq!(font(""), None);
+    assert_eq!(font("Times New Roman").as_deref(), Some("Times New Roman"));
+}
+
 /// The font table's family classes: Word draws a missing roman font in a serif face.
 #[test]
 fn roman_fonts_are_read_from_the_font_table() {

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity with Microsoft Word
 
-> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-14 · **Change:** trivial (missing roman fonts drawn in Cambria; previously trivial: legacy DOC DIB conversion honours the BLIP byte limit; related #1334 and #1554; previously trivial: right triangles keep their right angle; previously trivial: section `w:vAlign` "both" round-trips as Justified, #1320; previously trivial: Word's text watermark written back to DOCX headers, #1290; previously trivial: VML preset shapes drawn, #1377; previously trivial: VML text boxes keep their internal margins, fit to their text and vertical alignment; hidden drawings not shown; previously trivial: equations as MathML in HTML export, copy and paste, #816; previously trivial: symbol-font text exported as Unicode, #776; previously trivial: text-box margins, Resize shape to fit text and freeforms in groups, #743; previously trivial: formatted paste from the system clipboard's HTML and RTF, #687; previously trivial: independent complex-script formatting inheritance and round-trip regression tests; previously trivial: import/export fixes for TXT, RTF, ODT, HTML and LaTeX, #433–#440; previously major: first version; every format Word reads or writes, measured from the readers and writers on origin/main) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4, plus Word for Windows' extra formats
+> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-14 · **Change:** trivial (Bidi theme font slots; previously trivial: missing roman fonts drawn in Cambria; previously trivial: legacy DOC DIB conversion honours the BLIP byte limit; related #1334 and #1554; previously trivial: right triangles keep their right angle; previously trivial: section `w:vAlign` "both" round-trips as Justified, #1320; previously trivial: Word's text watermark written back to DOCX headers, #1290; previously trivial: VML preset shapes drawn, #1377; previously trivial: VML text boxes keep their internal margins, fit to their text and vertical alignment; hidden drawings not shown; previously trivial: equations as MathML in HTML export, copy and paste, #816; previously trivial: symbol-font text exported as Unicode, #776; previously trivial: text-box margins, Resize shape to fit text and freeforms in groups, #743; previously trivial: formatted paste from the system clipboard's HTML and RTF, #687; previously trivial: independent complex-script formatting inheritance and round-trip regression tests; previously trivial: import/export fixes for TXT, RTF, ODT, HTML and LaTeX, #433–#440; previously major: first version; every format Word reads or writes, measured from the readers and writers on origin/main) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4, plus Word for Windows' extra formats
 
 Every format Word opens or saves, what WordCraft does with it, and how it's tested. Fidelity is the
 share of a typical real-world file's content and formatting that survives (read: shows correctly;
@@ -195,6 +195,7 @@ attributes inside stories and style or list definitions; a regenerated theme. Te
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-14 | trivial | `minorBidi`/`majorBidi` theme fonts name the theme's complex-script font (`a:cs`); an empty one names nothing, so the inherited font applies, as measured in Word |
 | 2026-10-14 | trivial | A missing font the font table classes as roman is drawn in Cambria, as measured in Word (Calibri for the other classes, as before) |
 | 2026-10-14 | minor | Legacy DOC DIB helper honours the supplied byte limit for its BMP header/copy, decoder and PNG output, with a bounded BMP fallback. Generated 1-pixel regression only; resource-exhaustion consequences unmeasured, fidelity/readiness estimates unchanged. Related: #1334 and #1554 |
 | 2026-10-14 | trivial | Right triangles (`rtTriangle`) keep their right angle at the bottom left instead of becoming isosceles triangles, and save back as `rtTriangle` |