fix(music): preserve symbol-only title matching

app/domain/music.py

@@ -134,11 +134,23 @@ def music_base_title(value: Optional[str], *, preserve_editions: bool = False) -
     return _BARE_VERSION_SUFFIX.sub(strip_version, _VERSION_SUFFIX.sub(strip_version, text)).strip()
 
 
+def _music_title_key(value: Optional[str], *, preserve_editions: bool = False) -> str:
+    """生成音乐标题比较键，纯符号名称在普通归一化为空时保留其符号身份。"""
+    base = music_base_title(
+        normalize("NFKC", str(value or "")),
+        preserve_editions=preserve_editions,
+    )
+    key = music_text_key(base)
+    if key:
+        return key
+    return re.sub(r"\s+", "", base).casefold()
+
+
 def music_title_matches(music: MusicInfo, title: Optional[str], *, preserve_editions: bool = False) -> bool:
-    """统一全半角后比较完整名称及别名，允许数据源保持既有发行版本边界。"""
-    expected = music_text_key(music_base_title(normalize("NFKC", str(title or "")), preserve_editions=preserve_editions))
+    """统一全半角后比较完整名称及别名，纯符号名称也保留其身份。"""
+    expected = _music_title_key(title, preserve_editions=preserve_editions)
     return bool(expected and any(
-        expected == music_text_key(music_base_title(normalize("NFKC", name), preserve_editions=preserve_editions))
+        expected == _music_title_key(name, preserve_editions=preserve_editions)
         for name in music_titles(music)
     ))
 
@@ -229,7 +241,7 @@ def _resource_names(primary: MetaMusic, artists: list[str], *, album: bool = Fal
             variants.append(parts[0])
         for part in variants:
             name = music_base_title(_TITLE_LABEL.sub("", part.strip()))
-            key = music_text_key(name)
+            key = _music_title_key(name)
             if not key:
                 continue
             names.append(key)
@@ -323,7 +335,7 @@ def match_music_resource(
         else any(_contains_artist(content, artist) for artist in artists)
     if not title_matched:
         if music.music_type != MUSIC_ENTITY_ALBUM and artist_matched and any(
-            music_text_key(music_base_title(item)) in names
+            _music_title_key(item) in names
             for item in music_titles(music, album=True)
         ):
             return MusicMatch("album", "related_album")
@@ -338,7 +350,7 @@ def match_music_resource(
         # 所属专辑只说明单曲归属，不能代替资源主标题证明整专范围。
         primary_names = _resource_names(resource, artists)
         if resource.track_number or (resource.album and not any(
-            music_text_key(music_base_title(item)) in primary_names for item in titles
+            _music_title_key(item) in primary_names for item in titles
         )):
             return MusicMatch("candidate", "partial_album")
         if music.year and resource.year and str(music.year) != str(resource.year):

tests/test_music_matching.py

@@ -156,6 +156,39 @@ def test_soundtrack_credit_does_not_change_recording_title(title):
     assert music_title_matches(MusicInfo(title=expected), title)
 
 
+@pytest.mark.parametrize("symbol", ["÷", "+", "=", "×", "−"])
+def test_symbol_only_music_title_matches_itself_and_alias(symbol):
+    """纯符号作品名不能因文本归一化为空而失去自身和别名匹配。"""
+    music = MusicInfo(title=symbol, title_aliases=["Readable Alias"])
+
+    assert music_title_matches(music, symbol)
+    assert music_title_matches(music, "Readable Alias")
+    assert not music_title_matches(music, "Different Title")
+
+
+@pytest.mark.parametrize("symbol,alias,year", [
+    ("÷", "Divide", 2017),
+    ("+", "Plus", 2011),
+    ("=", "Equals", 2021),
+    ("×", "Multiply", 2017),
+    ("−", "Subtract", 2023),
+])
+def test_symbol_only_album_matches_parsed_resource(symbol, alias, year):
+    """纯符号专辑经资源解析后仍应按原名或可信别名精确命中。"""
+    music = MusicInfo(
+        music_type="album",
+        title=symbol,
+        album=symbol,
+        title_aliases=[alias],
+        album_aliases=[alias],
+        artists=["Ed Sheeran"],
+        year=year,
+    )
+
+    resource = f"Ed Sheeran - {symbol} - {year} - FLAC 分轨"
+    assert match_music_resource(music, resource).status == "exact"
+
+
 def test_music_album_field_cannot_match_target_recording():
     """结构化资源中的所属专辑不能冒充同名目标单曲。"""
     music = MusicInfo(title="Album", artists=["Artist"])