pyproject(mypy): add sphinx_fonts to ignore_missing_imports

why: sphinx_fonts is a local docs/_ext extension, not an installed
package — mypy cannot resolve it at analysis time.
what:
- Add sphinx_fonts to [[tool.mypy.overrides]] ignore_missing_imports

Author: tony

pyproject.toml

@@ -161,6 +161,7 @@ module = [
   "shtab",
   "sphinx_argparse_neo",
   "sphinx_argparse_neo.*",
+  "sphinx_fonts",
   "cli_usage_lexer",
   "argparse_lexer",
   "argparse_roles",

tests/docs/_ext/test_sphinx_fonts.py

@@ -183,6 +183,27 @@ def fake_urlretrieve(url: str, filename: t.Any) -> t.NoReturn:
     assert any("failed" in r.message for r in warning_records)
 
 
+def test_download_font_partial_file_cleanup(
+    tmp_path: pathlib.Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """_download_font removes partial file on failure."""
+    dest = tmp_path / "cache" / "partial.woff2"
+
+    msg = "disk full"
+
+    def fake_urlretrieve(url: str, filename: t.Any) -> t.NoReturn:
+        pathlib.Path(filename).write_bytes(b"partial")
+        raise OSError(msg)
+
+    monkeypatch.setattr("sphinx_fonts.urllib.request.urlretrieve", fake_urlretrieve)
+
+    result = sphinx_fonts._download_font("https://example.com/font.woff2", dest)
+
+    assert result is False
+    assert not dest.exists()
+
+
 # --- _on_builder_inited tests ---
 
 
@@ -262,7 +283,7 @@ def test_on_builder_inited_download_failure(
     tmp_path: pathlib.Path,
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
-    """_on_builder_inited still builds font_faces entry on download failure."""
+    """_on_builder_inited skips font_faces entry on download failure."""
     monkeypatch.setattr("sphinx_fonts._cache_dir", lambda: tmp_path / "cache")
 
     msg = "offline"
@@ -285,8 +306,7 @@ def fake_urlretrieve(url: str, filename: t.Any) -> t.NoReturn:
 
     sphinx_fonts._on_builder_inited(app)
 
-    assert len(app._font_faces) == 1
-    assert app._font_faces[0]["family"] == "Inter"
+    assert len(app._font_faces) == 0
 
 
 def test_on_builder_inited_explicit_subset(