feat(word-html): improve preview fidelity for tracked changes and CJK layout

src/officecli/Core/FontMetricsReader.cs

@@ -13,6 +13,32 @@ namespace OfficeCli.Core;
 /// </summary>
 internal static class FontMetricsReader
 {
+    // MOD(#12): see docs/cove-desktop-mods.md
+    // Word documents often specify Windows logical CJK family names such as
+    // "宋体" / "黑体", while macOS ships the actual font files under stems like
+    // Songti.ttc / STHeiti.ttc. Metrics lookup must follow the same alias/fallback
+    // path as the preview CSS, otherwise GetRatio() falls back to 1.0 and the
+    // rendered line-height becomes much tighter than the browser's real glyph box.
+    private static readonly Dictionary<string, string[]> s_fontSearchAliases = new(StringComparer.OrdinalIgnoreCase)
+    {
+        ["宋体"] = ["Songti", "Songti SC", "STSong", "SimSun", "NSimSun"],
+        ["宋体-简"] = ["Songti", "Songti SC", "STSong"],
+        ["宋體-簡"] = ["Songti", "Songti SC", "STSong"],
+        ["SimSun"] = ["Songti", "Songti SC", "STSong", "宋体"],
+        ["NSimSun"] = ["Songti", "Songti SC", "STSong", "宋体"],
+        ["黑体"] = ["STHeiti", "Heiti SC", "Heiti TC", "SimHei"],
+        ["SimHei"] = ["STHeiti", "Heiti SC", "Heiti TC", "黑体"],
+        ["仿宋_GB2312"] = ["STFangsong", "FangSong", "仿宋"],
+        ["仿宋"] = ["STFangsong", "FangSong", "仿宋_GB2312"],
+        ["楷体_GB2312"] = ["STKaiti", "KaiTi", "楷体"],
+        ["楷体"] = ["STKaiti", "KaiTi", "楷体_GB2312"],
+        ["长城小标宋体"] = ["STZhongsong", "Songti", "STSong"],
+        ["Songti SC"] = ["Songti", "STSong", "宋体"],
+        ["STSong"] = ["Songti", "Songti SC", "宋体"],
+        ["Heiti SC"] = ["STHeiti", "黑体"],
+        ["STHeiti"] = ["Heiti SC", "黑体"],
+    };
+
     /// <summary>
     /// Line-height ratio = (usWinAscent + usWinDescent + hheaLineGap) / unitsPerEm.
     /// Returns 1.0 if the font file cannot be read.
@@ -152,24 +178,44 @@ private static uint ReadUInt32BE(BinaryReader r)
             dirs.Add("/usr/local/share/fonts");
         }
 
-        // Normalize: remove spaces, try exact match and lowercase
-        var normalized = fontFamily.Replace(" ", "");
+        // Normalize: remove spaces, try exact match and platform fallback aliases.
+        var candidates = ExpandFontSearchAliases(fontFamily)
+            .Select(NormalizeFontSearchToken)
+            .Where(token => !string.IsNullOrWhiteSpace(token))
+            .Distinct(StringComparer.OrdinalIgnoreCase)
+            .ToArray();
         foreach (var dir in dirs)
         {
             if (!Directory.Exists(dir)) continue;
             foreach (var file in Directory.EnumerateFiles(dir, "*.*", SearchOption.AllDirectories))
             {
                 var ext = Path.GetExtension(file);
                 if (ext is not (".ttf" or ".otf" or ".ttc")) continue;
-                var stem = Path.GetFileNameWithoutExtension(file);
-                if (stem.Equals(normalized, StringComparison.OrdinalIgnoreCase)
-                    || stem.Equals(fontFamily, StringComparison.OrdinalIgnoreCase))
+                var stem = NormalizeFontSearchToken(Path.GetFileNameWithoutExtension(file));
+                if (candidates.Any(candidate => stem.Equals(candidate, StringComparison.OrdinalIgnoreCase)))
                     return file;
             }
         }
         return null;
     }
 
+    private static IEnumerable<string> ExpandFontSearchAliases(string fontFamily)
+    {
+        yield return fontFamily;
+
+        if (s_fontSearchAliases.TryGetValue(fontFamily, out var aliases))
+        {
+            foreach (var alias in aliases)
+                yield return alias;
+        }
+    }
+
+    private static string NormalizeFontSearchToken(string value) =>
+        value
+            .Replace(" ", "", StringComparison.Ordinal)
+            .Replace("-", "", StringComparison.Ordinal)
+            .Replace("_", "", StringComparison.Ordinal);
+
     // ==================== Cached Ratio Lookup ====================
 
     private static readonly Dictionary<string, double> s_ratioCache = new(StringComparer.OrdinalIgnoreCase);

src/officecli/Core/SpacingConverter.cs

@@ -32,7 +32,7 @@ internal static class SpacingConverter
     private const double PointsPerCm = 72.0 / 2.54; // ~28.3465
     private const double PointsPerInch = 72.0;
     private const int TwipsPerPoint = 20; // 1 pt = 20 twips
-    private const int WordAutoLineSpacingUnit = 240; // 240 twips = single line in Auto mode
+    private const int WordAutoLineSpacingUnit = 288; // MOD: 288 twips (14.4pt) better matches WPS/Chinese Word default row height for 16pt fonts // 240 twips = single line in Auto mode
 
     // ────────────────────────────────────────────────────────────────
     //  spaceBefore / spaceAfter  →  Word twips

src/officecli/Handlers/Word/WordHandler.Helpers.cs

@@ -1391,7 +1391,7 @@ private static PageMargin EnsureSectPrPageMargin(SectionProperties sectPr)
         var existing = sectPr.GetFirstChild<PageMargin>();
         if (existing != null) return existing;
 
-        var pm = new PageMargin();
+        var pm = new PageMargin { Top = 1440, Bottom = 1440, Left = 1800, Right = 1800, Header = 851, Footer = 992 };
         // Insert after PageSize if present, after SectionType, after last headerRef/footerRef, or prepend
         var pageSize = sectPr.GetFirstChild<PageSize>();
         if (pageSize != null)