Revert "feat: 侧边栏新增位置兼容模式，为 Windows 原生标题栏预留顶部空间"

This reverts commit ae71aecb83.

src/client/SideCardSection.tsx

@@ -660,17 +660,6 @@ export function SideCardSection({ store, service }: SideCardSectionProps) {
             onChange={(next) => { applyPref({ interceptOpenPath: next }) }}
           />
         </div>
-        <div className={css.row}>
-          <span className={css.rowText}>
-            <span className={css.title}>{t('settingsTitleBarTitle')}</span>
-            <span className={css.desc}>{t('settingsTitleBarDesc')}</span>
-          </span>
-          <Switch
-            label={t('settingsTitleBarTitle')}
-            checked={prefs.titleBarCompat}
-            onChange={(next) => { applyPref({ titleBarCompat: next }) }}
-          />
-        </div>
       </div>
 
       {/* 侧边栏内容: one small card per registered tab type in a responsive

src/client/Sidebar.tsx

@@ -167,21 +167,6 @@ export function Sidebar(props: { ctx: Context; store: SidebarStore }) {
     return () => { document.body.removeAttribute('data-dsh-sidebar-collapsed') }
   }, [collapsed])
 
-  // Position compatibility mode (titleBarCompat pref): Windows frameless
-  // windows draw the native title bar (minimize/maximize/close) at the
-  // window's top-right corner, OVER the web content. When the user enables
-  // the pref, the body attribute lets sidebar.module.css drop the toggle
-  // cluster below the strip and push the right panel's content below it.
-  // The attribute rides the snapshot's prefs, so flipping the setting
-  // re-renders and re-applies immediately; the cleanup removes it on
-  // unmount/boundary swap so a crashed sidebar never leaves it behind.
-  const titleBarCompat = snapshot.prefs.titleBarCompat
-  useEffect(() => {
-    if (titleBarCompat) document.body.setAttribute('data-dsh-title-bar-compat', '')
-    else document.body.removeAttribute('data-dsh-title-bar-compat')
-    return () => { document.body.removeAttribute('data-dsh-title-bar-compat') }
-  }, [titleBarCompat])
-
   /**
    * Bottom-panel merge on narrow viewports: whenever a session is current
    * while narrow (mount, session switch, or a desktop→narrow transition),

src/client/locales.ts

@@ -116,8 +116,6 @@ export const zh = {
   settingsWidthSuffix: '%',
   settingsOpenPathTitle: '聊天区文件在侧边栏打开',
   settingsOpenPathDesc: '在聊天里点击文件链接（工具行、产物列表、文件提及）时，在侧边栏编辑器中打开，不再调用系统默认应用',
-  settingsTitleBarTitle: '位置兼容模式',
-  settingsTitleBarDesc: '为 Windows 右上角的原生标题栏预留空间：侧边栏按钮与侧边栏内容整体下移，避免被标题栏遮挡',
   settingsSaveFailed: '保存失败',
   settingsConflict: '设置已被其他窗口修改，请重试',
   binaryNoPreview: '此文件类型不支持预览',
@@ -335,8 +333,6 @@ export const en: Record<keyof typeof zh, string> = {
   settingsWidthSuffix: '%',
   settingsOpenPathTitle: 'Open chat files in the sidebar',
   settingsOpenPathDesc: 'Open file links in the chat (tool rows, produced files, mentions) in the sidebar editor instead of the system default app',
-  settingsTitleBarTitle: 'Position compatibility mode',
-  settingsTitleBarDesc: 'Reserve space for the native Windows title bar at the top-right so the sidebar buttons and content sit below it instead of underneath',
   settingsSaveFailed: 'Failed to save',
   settingsConflict: 'The setting changed in another window — please retry',
   binaryNoPreview: 'This file type cannot be previewed',

src/client/prefs.ts

@@ -59,9 +59,6 @@ export function parsePrefs(value: unknown): SidebarPrefs {
     interceptOpenPath: typeof record.interceptOpenPath === 'boolean'
       ? record.interceptOpenPath
       : SIDEBAR_PREFS_DEFAULTS.interceptOpenPath,
-    titleBarCompat: typeof record.titleBarCompat === 'boolean'
-      ? record.titleBarCompat
-      : SIDEBAR_PREFS_DEFAULTS.titleBarCompat,
     htmlViewerNoSandbox: typeof record.htmlViewerNoSandbox === 'boolean'
       ? record.htmlViewerNoSandbox
       : SIDEBAR_PREFS_DEFAULTS.htmlViewerNoSandbox,

src/client/sidebar.module.css

@@ -209,28 +209,6 @@
   padding-right: 40px;
 }
 
-/* ── Position compatibility mode (Windows native title bar) ────────────── */
-
-/* Windows frameless / hidden-title-bar windows draw the native caption
-   strip (minimize / maximize / close) at the window's top-right corner,
-   OVER the web content. When the user enables the "position compatibility"
-   pref, the sidebar yields the strip: the toggle cluster drops below it and
-   the right panel's content starts below it — the panel's surface still
-   spans the full height, so the caption buttons float over empty sidebar
-   fill (the VSCode hidden-title-bar look). The bottom panel is unaffected:
-   it sits at the window's bottom, never under the top strip. The Sidebar
-   shell toggles the body attribute from the prefs. */
-:global(body[data-dsh-title-bar-compat]) .toggleCluster {
-  top: 43px; /* 40px caption strip + the original 3px inset */
-}
-
-:global(body[data-dsh-title-bar-compat]) .panel {
-  /* The caption strip is drawn over the panel's own top edge: keep the
-     surface full-height and push the content (the tab strip) below the
-     strip instead. .panelResize is absolutely positioned and unaffected. */
-  padding-top: 40px;
-}
-
 /* The shared corner (both panels open): the intersection of the right
    panel's left edge and the bottom panel's top edge. Horizontal drags
    resize the width, vertical drags the height — the two panels drag