fix(docx): preserve East Asian language w:eastAsia on w:lang

Preserve w:lang/@w:eastAsia when reading and writing DOCX documents.
Previously, only w:val and w:bidi were handled, causing w:eastAsia to be
dropped on save.

Fixes #3457

crates/doc/src/props.rs

@@ -421,6 +421,9 @@ pub struct CharProps {
     /// BCP 47 language of complex-script text (`w:lang/@w:bidi`, e.g. `fa-IR`).
     #[serde(skip_serializing_if = "Option::is_none")]
     pub lang_bidi: Option<String>,
+    /// BCP 47 language of East Asian text (`w:lang/@w:eastAsia`, e.g. `zh-CN`, `ja-JP`, `ko-KR`).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub lang_ea: Option<String>,
     /// East Asian typography: two lines in one and horizontal in vertical (`w:eastAsianLayout`).
     /// Kept for round trip; layout doesn't apply it yet.
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -549,7 +552,7 @@ impl CharProps {
     pub fn minus(mut self, base: &CharProps) -> CharProps {
         drop_same_fields!(self, base; style, font, sym_font, size, bold, italic, underline, underline_color, strike, double_strike, color, highlight,
             shading, border, vert_align, caps, small_caps, hidden, spacing, scale, position, kern, outline, shadow, emboss, engrave, lang, no_proof, rtl,
-            cs, font_cs, size_cs, bold_cs, italic_cs, lang_bidi, east_asian_layout, link, ins, del, ligatures);
+            cs, font_cs, font_ea, size_cs, bold_cs, italic_cs, lang_bidi, lang_ea, east_asian_layout, link, ins, del, ligatures);
         self
     }
 
@@ -560,7 +563,7 @@ impl CharProps {
     pub fn overlay(&mut self, patch: &CharProps) {
         overlay_fields!(self, patch; style, font, sym_font, size, bold, italic, underline, underline_color, strike, double_strike, color, highlight,
             shading, border, vert_align, caps, small_caps, hidden, spacing, scale, position, kern, outline, shadow, emboss, engrave, lang, no_proof, rtl,
-            cs, font_cs, font_ea, size_cs, bold_cs, italic_cs, lang_bidi, east_asian_layout, link, ins, del, fmt_change, ligatures);
+            cs, font_cs, font_ea, size_cs, bold_cs, italic_cs, lang_bidi, lang_ea, east_asian_layout, link, ins, del, fmt_change, ligatures);
         if let Some(p) = &patch.text_effects {
             self.text_effects.get_or_insert_with(Default::default).overlay(p);
         }

crates/docx/src/read/props.rs

@@ -227,8 +227,9 @@ impl PropCtx {
                     c.east_asian_layout = (l != EastAsianLayout::default()).then_some(l);
                 }
                 "w:lang" => {
-                    c.lang = k.attr("w:val").filter(|v| !v.is_empty() && v.len() < 64).map(str::to_string);
-                    c.lang_bidi = k.attr("w:bidi").filter(|v| !v.is_empty() && v.len() < 64).map(str::to_string);
+                    c.lang = k.attr("w:val").map(str::trim).filter(|v| !v.is_empty() && v.len() < 64).map(str::to_string);
+                    c.lang_bidi = k.attr("w:bidi").map(str::trim).filter(|v| !v.is_empty() && v.len() < 64).map(str::to_string);
+                    c.lang_ea = k.attr("w:eastAsia").map(str::trim).filter(|v| !v.is_empty() && v.len() < 64).map(str::to_string);
                 }
                 "w14:ligatures" => c.ligatures = k.attr("w14:val").and_then(wordcraft_doc::props::Ligatures::from_ooxml),
                 n if n.starts_with("w14:") => {

crates/docx/src/write/props.rs

@@ -106,11 +106,18 @@ pub fn rpr_inner(w: &mut W, c: &CharProps) {
     }
     toggle(w, "w:rtl", c.rtl);
     toggle(w, "w:cs", c.cs);
-    match (&c.lang, &c.lang_bidi) {
-        (Some(l), Some(b)) => w.empty("w:lang", &[("w:val", l), ("w:bidi", b)]),
-        (Some(l), None) => w.val("w:lang", l),
-        (None, Some(b)) => w.empty("w:lang", &[("w:bidi", b)]),
-        (None, None) => {}
+    let mut lang_attrs: Vec<(&str, &str)> = Vec::with_capacity(3);
+    if let Some(l) = &c.lang {
+        lang_attrs.push(("w:val", l));
+    }
+    if let Some(ea) = &c.lang_ea {
+        lang_attrs.push(("w:eastAsia", ea));
+    }
+    if let Some(b) = &c.lang_bidi {
+        lang_attrs.push(("w:bidi", b));
+    }
+    if !lang_attrs.is_empty() {
+        w.empty("w:lang", &lang_attrs);
     }
     // After w:lang (CT_RPr's sequence).
     if let Some(l) = &c.east_asian_layout {

crates/docx/tests/east_asian_lang.rs

@@ -0,0 +1,85 @@
+//! East Asian language attribute of a run (`w:lang/@w:eastAsia`, ISO/IEC 29500-1 §17.3.2.20).
+//! Verifies that saving DOCX documents preserves the East Asian language of `w:lang`.
+
+use std::io::{Read, Write};
+
+fn docx(body: &str, styles: Option<&str>) -> Vec<u8> {
+    let root = r#"<?xml version="1.0" encoding="UTF-8"?><Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/></Relationships>"#;
+    let doc_rels = r#"<?xml version="1.0" encoding="UTF-8"?><Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/></Relationships>"#;
+    let doc = format!(
+        r#"<?xml version="1.0" encoding="UTF-8" standalone="yes"?><w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body>{body}</w:body></w:document>"#
+    );
+    let mut parts = vec![("_rels/.rels", root.to_string()), ("word/document.xml", doc)];
+    if let Some(s) = styles {
+        parts.push(("word/_rels/document.xml.rels", doc_rels.to_string()));
+        parts.push((
+            "word/styles.xml",
+            format!(r#"<?xml version="1.0" encoding="UTF-8" standalone="yes"?><w:styles xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">{s}</w:styles>"#),
+        ));
+    }
+    let mut zw = zip::ZipWriter::new(std::io::Cursor::new(Vec::new()));
+    for (name, xml) in &parts {
+        zw.start_file(*name, zip::write::SimpleFileOptions::default()).unwrap();
+        zw.write_all(xml.as_bytes()).unwrap();
+    }
+    zw.finish().unwrap().into_inner()
+}
+
+fn part(bytes: &[u8], name: &str) -> String {
+    let mut z = zip::ZipArchive::new(std::io::Cursor::new(bytes)).unwrap();
+    let mut s = String::new();
+    z.by_name(name).unwrap().read_to_string(&mut s).unwrap();
+    s
+}
+
+fn run(text: &str, rpr: &str) -> String {
+    format!(r#"<w:r><w:rPr>{rpr}</w:rPr><w:t>{text}</w:t></w:r>"#)
+}
+
+#[test]
+fn east_asian_lang_survives_a_save() {
+    let body = format!(
+        r#"<w:p>{}{}</w:p>"#,
+        run("Hello", r#"<w:lang w:val="en-US" w:eastAsia="ja-JP" w:bidi="ar-SA"/>"#),
+        run("中文", r#"<w:lang w:eastAsia="zh-CN"/>"#)
+    );
+    let d = wordcraft_docx::read(&docx(&body, None)).unwrap();
+    let p = d.body[0].as_para().unwrap();
+
+    let r0 = &p.runs[0];
+    assert_eq!(r0.props.lang.as_deref(), Some("en-US"));
+    assert_eq!(r0.props.lang_ea.as_deref(), Some("ja-JP"));
+    assert_eq!(r0.props.lang_bidi.as_deref(), Some("ar-SA"));
+
+    let r1 = &p.runs[1];
+    assert_eq!(r1.props.lang, None);
+    assert_eq!(r1.props.lang_ea.as_deref(), Some("zh-CN"));
+    assert_eq!(r1.props.lang_bidi, None);
+
+    let out = wordcraft_docx::write(&d).unwrap();
+    let xml = part(&out, "word/document.xml");
+    assert!(xml.contains(r#"w:eastAsia="ja-JP""#), "{xml}");
+    assert!(xml.contains(r#"w:eastAsia="zh-CN""#), "{xml}");
+
+    let back = wordcraft_docx::read(&out).unwrap();
+    let back_p = back.body[0].as_para().unwrap();
+    assert_eq!(back_p.runs[0].props.lang.as_deref(), Some("en-US"));
+    assert_eq!(back_p.runs[0].props.lang_ea.as_deref(), Some("ja-JP"));
+    assert_eq!(back_p.runs[0].props.lang_bidi.as_deref(), Some("ar-SA"));
+    assert_eq!(back_p.runs[1].props.lang_ea.as_deref(), Some("zh-CN"));
+}
+
+#[test]
+fn east_asian_lang_style_and_whitespace_trim() {
+    let styles =
+        r#"<w:style w:type="character" w:styleId="CJKLang"><w:name w:val="CJK Language"/><w:rPr><w:lang w:eastAsia="  ko-KR  "/></w:rPr></w:style>"#;
+    let body = format!(r#"<w:p>{}</w:p>"#, run("한국어", r#"<w:rStyle w:val="CJKLang"/>"#));
+    let d = wordcraft_docx::read(&docx(&body, Some(styles))).unwrap();
+
+    let style = d.styles.get("CJKLang").unwrap();
+    assert_eq!(style.chr.lang_ea.as_deref(), Some("ko-KR"));
+
+    let out = wordcraft_docx::write(&d).unwrap();
+    let styles_xml = part(&out, "word/styles.xml");
+    assert!(styles_xml.contains(r#"w:eastAsia="ko-KR""#), "{styles_xml}");
+}

crates/docx/tests/roundtrip.rs

@@ -113,6 +113,7 @@ fn every_char_prop_round_trips() {
         bold_cs: Some(false),
         italic_cs: Some(true),
         lang_bidi: Some("fa-IR".into()),
+        lang_ea: Some("ja-JP".into()),
         east_asian_layout: Some(wordcraft_doc::props::EastAsianLayout {
             id: Some(3),
             combine: Some(true),

crates/layout/src/outline.rs

@@ -124,6 +124,7 @@ fn plain_chars(c: &CharProps) -> CharProps {
         rtl: c.rtl,
         cs: c.cs,
         lang_bidi: c.lang_bidi.clone(),
+        lang_ea: c.lang_ea.clone(),
         link: c.link.clone(),
         ins: c.ins,
         del: c.del,