Fix zero-area contours after export to TTF

README.md

@@ -87,4 +87,12 @@ Several metadata scripts are applied via FontForge:
 
 #### Step 4: Export
 
-The final fonts are exported from FontForge as both SFD (FontForge source) and TTF. The build supports optional old-style kern tables, but this is off by default because it has no effect on device tests.
+The final fonts are exported from FontForge as TTF. A cleanup step removes zero-area contours that can cause missing glyphs on macOS. The build supports optional old-style kern tables, but this is off by default because it has no effect on device tests.
+
+#### TTF cleanup (manual exports)
+
+Some FontForge exports emit 1–2 point contours in the `glyf` table. macOS can treat these as invalid and skip the glyph entirely (for example, `m` or italic `u`). The build pipeline removes these zero-area contours automatically. If you manually export a TTF from an SFD and see missing glyphs, run:
+
+```
+python3 cleanup_ttf.py out/ttf/Readerly-Regular.ttf
+```

build.py

@@ -179,7 +179,7 @@ def build_export_script(sfd_path, ttf_path, old_kern=True):
 
 
 def clean_ttf_degenerate_contours(ttf_path):
-    """Remove degenerate contours (<=2 points) from a TTF in-place."""
+    """Remove zero-area contours (<=2 points) from a TTF in-place."""
     try:
         from fontTools.ttLib import TTFont
         from fontTools.ttLib.tables._g_l_y_f import GlyphCoordinates
@@ -236,7 +236,7 @@ def clean_ttf_degenerate_contours(ttf_path):
         if hasattr(glyf, "recalcBounds"):
             glyf.recalcBounds(glyph_set)  # type: ignore[attr-defined]
         font.save(ttf_path)
-        print(f"  Cleaned {removed_total} degenerate contour(s)")
+        print(f"  Cleaned {removed_total} zero-area contour(s)")
     font.close()
 
 
@@ -305,6 +305,7 @@ def _build(tmp_dir, family=DEFAULT_FAMILY, old_kern=True):
                 print(result.stderr, file=sys.stderr)
             sys.exit(1)
 
+
     print(f"  {len(variants)} font(s) instanced.")
 
     # Step 2: Apply vertical scale (opens TTF, saves as SFD)
@@ -374,6 +375,7 @@ def _build(tmp_dir, family=DEFAULT_FAMILY, old_kern=True):
         run_fontforge_script(script)
         clean_ttf_degenerate_contours(ttf_path)
 
+
     print("\n" + "=" * 60)
     print("  Build complete!")
     print(f"  SFD fonts are in: {OUT_SFD_DIR}/")

cleanup_ttf.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+"""
+Remove zero-area contours from a TTF.
+
+Some FontForge exports emit 1–2 point contours that macOS can treat as
+invalid and skip the glyph entirely. This script removes those contours
+in-place.
+"""
+
+import sys
+
+
+def clean_ttf_degenerate_contours(ttf_path):
+    try:
+        from fontTools.ttLib import TTFont
+        from fontTools.ttLib.tables._g_l_y_f import GlyphCoordinates
+    except Exception as exc:
+        raise SystemExit(f"ERROR: fontTools is required ({exc})")
+
+    font = TTFont(ttf_path)
+    glyf = font["glyf"]  # type: ignore[index]
+
+    removed_total = 0
+    modified = set()
+    for name in font.getGlyphOrder():
+        glyph = glyf[name]  # type: ignore[index]
+        if glyph.isComposite():
+            continue
+        end_pts = getattr(glyph, "endPtsOfContours", None)
+        if not end_pts:
+            continue
+
+        coords = glyph.coordinates
+        flags = glyph.flags
+
+        new_coords = []
+        new_flags = []
+        new_end_pts = []
+
+        start = 0
+        removed = 0
+        for end in end_pts:
+            count = end - start + 1
+            if count <= 2:
+                removed += 1
+            else:
+                new_coords.extend(coords[start:end + 1])
+                new_flags.extend(flags[start:end + 1])
+                new_end_pts.append(len(new_coords) - 1)
+            start = end + 1
+
+        if removed:
+            removed_total += removed
+            modified.add(name)
+            glyph.coordinates = GlyphCoordinates(new_coords)
+            glyph.flags = new_flags
+            glyph.endPtsOfContours = new_end_pts
+            glyph.numberOfContours = len(new_end_pts)
+
+    if removed_total:
+        glyph_set = font.getGlyphSet()
+        for name in modified:
+            glyph = glyf[name]  # type: ignore[index]
+            if hasattr(glyph, "recalcBounds"):
+                glyph.recalcBounds(glyph_set)
+        if hasattr(glyf, "recalcBounds"):
+            glyf.recalcBounds(glyph_set)  # type: ignore[attr-defined]
+        font.save(ttf_path)
+
+    font.close()
+    return removed_total
+
+
+def main():
+    if len(sys.argv) != 2:
+        raise SystemExit("Usage: python3 cleanup_ttf.py path/to/font.ttf")
+    ttf_path = sys.argv[1]
+    removed = clean_ttf_degenerate_contours(ttf_path)
+    print(f"Cleaned {removed} zero-area contour(s): {ttf_path}")
+
+
+if __name__ == "__main__":
+    main()