fix: 修复 Codex 审查发现的两处回归

- Bangumi / BangumiUpdate 的 9 个可空字段恢复为必填（default=...），只传部分字段的更新与订阅请求重新返回 422，不再用占位值改写规则和保存路径
- ab-menu 补上 role=menu、打开时把焦点移到菜单、aria-activedescendant 指向高亮项，关闭后焦点回到触发器

backend/src/module/models/bangumi.py

@@ -10,32 +10,30 @@ class Bangumi(SQLModel, table=True):
     official_title: str = Field(
         default="official_title", alias="official_title", title="番剧中文名"
     )
-    year: Optional[str] = Field(default=None, alias="year", title="番剧年份")
+    year: Optional[str] = Field(default=..., alias="year", title="番剧年份")
     title_raw: str = Field(
         default="title_raw", alias="title_raw", title="番剧原名", index=True
     )
     season: int = Field(default=1, alias="season", title="番剧季度")
     season_raw: Optional[str] = Field(
-        default=None, alias="season_raw", title="番剧季度原名"
+        default=..., alias="season_raw", title="番剧季度原名"
     )
-    group_name: Optional[str] = Field(default=None, alias="group_name", title="字幕组")
-    dpi: Optional[str] = Field(default=None, alias="dpi", title="分辨率")
-    source: Optional[str] = Field(default=None, alias="source", title="来源")
-    subtitle: Optional[str] = Field(default=None, alias="subtitle", title="字幕")
+    group_name: Optional[str] = Field(default=..., alias="group_name", title="字幕组")
+    dpi: Optional[str] = Field(default=..., alias="dpi", title="分辨率")
+    source: Optional[str] = Field(default=..., alias="source", title="来源")
+    subtitle: Optional[str] = Field(default=..., alias="subtitle", title="字幕")
     eps_collect: bool = Field(default=False, alias="eps_collect", title="是否已收集")
     episode_offset: int = Field(default=0, alias="episode_offset", title="集数偏移量")
     season_offset: int = Field(default=0, alias="season_offset", title="季度偏移量")
     filter: str = Field(default="720,\\d+-\\d+", alias="filter", title="番剧过滤器")
     rss_link: str = Field(default="", alias="rss_link", title="番剧RSS链接")
     poster_link: Optional[str] = Field(
-        default=None, alias="poster_link", title="番剧海报链接"
+        default=..., alias="poster_link", title="番剧海报链接"
     )
     added: bool = Field(default=False, alias="added", title="是否已添加")
-    rule_name: Optional[str] = Field(
-        default=None, alias="rule_name", title="番剧规则名"
-    )
+    rule_name: Optional[str] = Field(default=..., alias="rule_name", title="番剧规则名")
     save_path: Optional[str] = Field(
-        default=None, alias="save_path", title="番剧保存路径"
+        default=..., alias="save_path", title="番剧保存路径"
     )
     deleted: bool = Field(
         default=False, alias="deleted", title="是否已删除", index=True
@@ -81,30 +79,28 @@ class BangumiUpdate(SQLModel):
     official_title: str = Field(
         default="official_title", alias="official_title", title="番剧中文名"
     )
-    year: Optional[str] = Field(default=None, alias="year", title="番剧年份")
+    year: Optional[str] = Field(default=..., alias="year", title="番剧年份")
     title_raw: str = Field(default="title_raw", alias="title_raw", title="番剧原名")
     season: int = Field(default=1, alias="season", title="番剧季度")
     season_raw: Optional[str] = Field(
-        default=None, alias="season_raw", title="番剧季度原名"
+        default=..., alias="season_raw", title="番剧季度原名"
     )
-    group_name: Optional[str] = Field(default=None, alias="group_name", title="字幕组")
-    dpi: Optional[str] = Field(default=None, alias="dpi", title="分辨率")
-    source: Optional[str] = Field(default=None, alias="source", title="来源")
-    subtitle: Optional[str] = Field(default=None, alias="subtitle", title="字幕")
+    group_name: Optional[str] = Field(default=..., alias="group_name", title="字幕组")
+    dpi: Optional[str] = Field(default=..., alias="dpi", title="分辨率")
+    source: Optional[str] = Field(default=..., alias="source", title="来源")
+    subtitle: Optional[str] = Field(default=..., alias="subtitle", title="字幕")
     eps_collect: bool = Field(default=False, alias="eps_collect", title="是否已收集")
     episode_offset: int = Field(default=0, alias="episode_offset", title="集数偏移量")
     season_offset: int = Field(default=0, alias="season_offset", title="季度偏移量")
     filter: str = Field(default="720,\\d+-\\d+", alias="filter", title="番剧过滤器")
     rss_link: str = Field(default="", alias="rss_link", title="番剧RSS链接")
     poster_link: Optional[str] = Field(
-        default=None, alias="poster_link", title="番剧海报链接"
+        default=..., alias="poster_link", title="番剧海报链接"
     )
     added: bool = Field(default=False, alias="added", title="是否已添加")
-    rule_name: Optional[str] = Field(
-        default=None, alias="rule_name", title="番剧规则名"
-    )
+    rule_name: Optional[str] = Field(default=..., alias="rule_name", title="番剧规则名")
     save_path: Optional[str] = Field(
-        default=None, alias="save_path", title="番剧保存路径"
+        default=..., alias="save_path", title="番剧保存路径"
     )
     downloader_id: Optional[str] = Field(
         default=None, alias="downloader_id", title="下载器实例"

backend/src/test/test_api_bangumi.py

@@ -152,6 +152,18 @@ class TestUpdateBangumi:
 
         assert response.status_code == 200
 
+    def test_update_partial_body_rejected(self, authed_client):
+        """只传部分字段时返回 422，不能用占位值改写规则与保存路径。"""
+        with patch("module.api.bangumi.TorrentManager") as MockManager:
+            mock_mgr = MockManager.return_value
+            mock_mgr.update_rule = AsyncMock()
+            response = authed_client.patch(
+                "/api/v1/bangumi/update/1", json={"year": "2025"}
+            )
+
+        assert response.status_code == 422
+        mock_mgr.update_rule.assert_not_called()
+
 
 # ---------------------------------------------------------------------------
 # DELETE endpoints

webui/src/components/basic/__tests__/ab-menu.test.ts

@@ -60,6 +60,28 @@ describe('ab-menu', () => {
     expect(trigger.attributes('aria-expanded')).toBe('true');
   });
 
+  it('should move focus into the menu and announce the highlighted item when opened', async () => {
+    const wrapper = mount(AbMenu, {
+      props: { items: items() },
+      slots: { trigger: '<button type="button">Actions</button>' },
+      attachTo: document.body,
+    });
+    const trigger = wrapper.find('button');
+    (trigger.element as HTMLElement).focus();
+    await trigger.trigger('click');
+    await flushPromises();
+    const menu = document.querySelector<HTMLElement>('[role="menu"]')!;
+    expect(document.activeElement).toBe(menu);
+
+    menu.dispatchEvent(new KeyboardEvent('keydown', { key: 'ArrowDown', bubbles: true }));
+    await flushPromises();
+    expect(menu.getAttribute('aria-activedescendant')).toBe(menuItems()[0].id);
+
+    menu.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }));
+    await flushPromises();
+    expect(document.activeElement).toBe(trigger.element);
+  });
+
   it('should mark danger items with the danger class', async () => {
     const wrapper = mount(AbMenu, {
       props: { items: items() },

webui/src/components/basic/ab-menu.vue

@@ -14,8 +14,9 @@ export interface AbMenuItem {
 }
 
 // 下拉菜单：naive-ui NDropdown 负责定位与键盘导航（方向键/回车/Esc）；
-// 触发器放在 #trigger 插槽。NDropdown 不输出 aria，menuitem 角色与
-// 触发器的 aria-haspopup/aria-expanded 在这里补上。
+// 触发器放在 #trigger 插槽。NDropdown 不输出 aria，也不移动焦点：这里补上
+// menu/menuitem 角色、触发器的 aria-haspopup/aria-expanded，打开时把焦点
+// 移到菜单容器，并用 aria-activedescendant 指向高亮项，读屏才能读出当前项。
 const { items, align = 'left' } = defineProps<{
   items: AbMenuItem[];
   /** 菜单相对触发器的对齐边 */
@@ -27,6 +28,8 @@ const emit = defineEmits<{ select: [item: AbMenuItem] }>();
 const slots = defineSlots<{ trigger: () => VNode[] }>();
 
 const open = ref(false);
+const listId = useId();
+const activeId = ref<string>();
 
 const options = computed<DropdownOption[]>(() =>
   items.map((item, index) => ({
@@ -35,7 +38,9 @@ const options = computed<DropdownOption[]>(() =>
     disabled: item.disabled,
     icon: item.icon && (() => h(item.icon!, { size: 15 })),
     props: {
+      id: `${listId}-${item.key ?? index}`,
       role: 'menuitem',
+      'aria-disabled': item.disabled || undefined,
       class: item.danger ? 'ab-menu-item--danger' : undefined,
     },
   }))
@@ -48,6 +53,38 @@ function Trigger() {
   });
 }
 
+// NDropdown 不暴露高亮项，只能从它的 --pending 类读出
+let observer: MutationObserver | undefined;
+let opener: HTMLElement | null = null;
+
+watch(open, async (isOpen) => {
+  observer?.disconnect();
+  activeId.value = undefined;
+  const list = document.getElementById(listId);
+  if (!isOpen) {
+    // 焦点留在正在关闭的菜单里或已丢到 body 时，还给触发器
+    const focused = document.activeElement;
+    if (focused === document.body || list?.contains(focused)) opener?.focus();
+    return;
+  }
+  opener = document.activeElement as HTMLElement | null;
+  await nextTick();
+  const menu = document.getElementById(listId);
+  if (!menu) return;
+  menu.focus({ preventScroll: true });
+  observer = new MutationObserver(() => {
+    activeId.value =
+      menu.querySelector('.n-dropdown-option-body--pending')?.id || undefined;
+  });
+  observer.observe(menu, {
+    subtree: true,
+    attributes: true,
+    attributeFilter: ['class'],
+  });
+});
+
+onBeforeUnmount(() => observer?.disconnect());
+
 function onSelect(key: string | number) {
   const item = items.find((entry, index) => (entry.key ?? index) === key);
   if (!item || item.disabled) return;
@@ -62,7 +99,15 @@ function onSelect(key: string | number) {
     :show="open"
     :options="options"
     :placement="align === 'right' ? 'bottom-end' : 'bottom-start'"
-    :menu-props="() => ({ class: 'ab-menu-list' })"
+    :menu-props="
+      () => ({
+        'id': listId,
+        'class': 'ab-menu-list',
+        'role': 'menu',
+        'tabindex': -1,
+        'aria-activedescendant': activeId,
+      })
+    "
     @update:show="open = $event"
     @select="onSelect"
   >
@@ -82,6 +127,11 @@ function onSelect(key: string | number) {
 .ab-menu-list {
   min-width: 180px;
 
+  // 焦点在容器上只为 aria-activedescendant，高亮项已经标出当前项
+  &:focus {
+    outline: none;
+  }
+
   // 触屏放大命中区域，与旧菜单一致
   @include forTouch {
     .n-dropdown-option-body {