diff --git a/src/client/SideCardSection.tsx b/src/client/SideCardSection.tsx
index 410cd1a..c0e4950 100644
--- a/src/client/SideCardSection.tsx
+++ b/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
diff --git a/src/client/Sidebar.tsx b/src/client/Sidebar.tsx
index d4537e0..8d4cafc 100644
--- a/src/client/Sidebar.tsx
+++ b/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),
diff --git a/src/client/locales.ts b/src/client/locales.ts
index 5dc6c07..fe66593 100644
--- a/src/client/locales.ts
+++ b/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',
diff --git a/src/client/prefs.ts b/src/client/prefs.ts
index ec92080..2d0895a 100644
--- a/src/client/prefs.ts
+++ b/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,
diff --git a/src/client/sidebar.module.css b/src/client/sidebar.module.css
index 0d765b9..68f709d 100644
--- a/src/client/sidebar.module.css
+++ b/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
diff --git a/src/config.ts b/src/config.ts
index 18582fb..5f0d4d3 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -91,7 +91,6 @@ export const PrefsSchema: z<SidebarPrefs> = z.object({
   terminalFontFamily: z.string().default(''),
   terminalFontSize: z.number().step(1).min(TERMINAL_FONT_SIZE_MIN).max(TERMINAL_FONT_SIZE_MAX).default(TERMINAL_FONT_SIZE_DEFAULT),
   interceptOpenPath: z.boolean().default(true),
-  titleBarCompat: z.boolean().default(false),
   htmlViewerNoSandbox: z.boolean().default(false),
   htmlViewerDefaultUnsafe: z.boolean().default(false),
   browserNoSandbox: z.boolean().default(false),
diff --git a/src/prefs-shared.ts b/src/prefs-shared.ts
index c0f04ed..0cd576d 100644
--- a/src/prefs-shared.ts
+++ b/src/prefs-shared.ts
@@ -60,14 +60,6 @@ export interface SidebarPrefs {
    * own enable switch gates it too (both must be on for the takeover).
    */
   interceptOpenPath: boolean
-  /**
-   * Position compatibility mode: reserves space at the top for the native
-   * Windows title bar (drawn at the window's top-right corner over the web
-   * content in frameless/hidden-title-bar windows). When on, the toggle
-   * cluster drops below the strip and the right panel's content starts
-   * below it. Off by default — the sidebar layout is untouched.
-   */
-  titleBarCompat: boolean
   /**
    * Whether the HTML previewer drops its sandboxed iframe. Sandbox ON (the
    * default) renders previewed HTML in an opaque-origin iframe that cannot
@@ -167,7 +159,6 @@ export const SIDEBAR_PREFS_DEFAULTS: SidebarPrefs = {
   terminalFontFamily: '',
   terminalFontSize: TERMINAL_FONT_SIZE_DEFAULT,
   interceptOpenPath: true,
-  titleBarCompat: false,
   htmlViewerNoSandbox: false,
   htmlViewerDefaultUnsafe: false,
   browserNoSandbox: false,
diff --git a/tests/plugin-shape.spec.ts b/tests/plugin-shape.spec.ts
index 8d0a0a7..c549ae1 100644
--- a/tests/plugin-shape.spec.ts
+++ b/tests/plugin-shape.spec.ts
@@ -54,8 +54,6 @@ describe('dsh-better-sidebar plugin export shape', () => {
     // and 13px.
     expect(resolved.terminalFontFamily).toBe('')
     expect(resolved.terminalFontSize).toBe(13)
-    // The position-compat mode defaults OFF (the normal layout is default).
-    expect(resolved.titleBarCompat).toBe(false)
     // The enable-switch maps resolve to {} (everything on) for old documents.
     expect(resolved.tabsEnabled).toEqual({})
     expect(resolved.viewersEnabled).toEqual({})
@@ -65,6 +63,6 @@ describe('dsh-better-sidebar plugin export shape', () => {
     const overridden = (PrefsSchema as unknown as {
       (input: Record<string, unknown> | undefined): Record<string, unknown>
     })({ openByDefault: false, defaultWidthPercent: 45 })
-    expect(overridden).toEqual({ openByDefault: false, defaultWidthPercent: 45, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, titleBarCompat: false, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
+    expect(overridden).toEqual({ openByDefault: false, defaultWidthPercent: 45, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
   })
 })
diff --git a/tests/side-card-section.spec.tsx b/tests/side-card-section.spec.tsx
index c7f860c..7246561 100644
--- a/tests/side-card-section.spec.tsx
+++ b/tests/side-card-section.spec.tsx
@@ -151,24 +151,6 @@ describe('SideCardSection declarative inventory', () => {
     const html = renderSection(store, service)
     expect(html).not.toContain('Feature settings')
   })
-
-  it('renders the position-compat mode general row: off by default, checked when the pref is on', () => {
-    const { store, service } = mount()
-    let html = renderSection(store, service)
-    // The general row renders its title and description.
-    expect(html).toContain('Position compatibility mode')
-    expect(html).toContain('Reserve space for the native Windows title bar')
-    // Three general rows now: openByDefault + interceptOpenPath checked,
-    // the new titleBarCompat row UNCHECKED (default off) — the checked
-    // checkbox count stays at 2 while the total checkbox count is 3.
-    expect(html.match(/type="checkbox"/g)?.length).toBe(3)
-    expect(html.match(/checked=""/g)?.length).toBe(2)
-
-    // When the pref is on, the new switch is checked too.
-    store.setPrefs({ ...store.getPrefs(), titleBarCompat: true })
-    html = renderSection(store, service)
-    expect(html.match(/checked=""/g)?.length).toBe(3)
-  })
 })
 
 describe('FeatureSettingsRows (the secondary settings popup body)', () => {
diff --git a/tests/smoke.spec.ts b/tests/smoke.spec.ts
index bacd3a2..5529fbf 100644
--- a/tests/smoke.spec.ts
+++ b/tests/smoke.spec.ts
@@ -520,7 +520,6 @@ describe('side card settings routes', () => {
         terminalFontFamily: '',
         terminalFontSize: 13,
         interceptOpenPath: true,
-        titleBarCompat: false,
         htmlViewerNoSandbox: false,
         htmlViewerDefaultUnsafe: false,
         browserNoSandbox: false,
diff --git a/tests/unit.spec.ts b/tests/unit.spec.ts
index 4229979..c3a965e 100644
--- a/tests/unit.spec.ts
+++ b/tests/unit.spec.ts
@@ -1140,7 +1140,6 @@ describe('side card preferences', () => {
         terminalFontFamily: '',
         terminalFontSize: 13,
         interceptOpenPath: true,
-        titleBarCompat: false,
         htmlViewerNoSandbox: false,
         htmlViewerDefaultUnsafe: false,
         browserNoSandbox: false,
@@ -1165,7 +1164,6 @@ describe('side card preferences', () => {
         terminalFontFamily: '',
         terminalFontSize: 13,
         interceptOpenPath: true,
-        titleBarCompat: false,
         htmlViewerNoSandbox: false,
         htmlViewerDefaultUnsafe: false,
         browserNoSandbox: false,
@@ -1190,7 +1188,6 @@ describe('side card preferences', () => {
         terminalFontFamily: '',
         terminalFontSize: 13,
         interceptOpenPath: true,
-        titleBarCompat: false,
         htmlViewerNoSandbox: false,
         htmlViewerDefaultUnsafe: false,
         browserNoSandbox: false,
@@ -1227,16 +1224,6 @@ describe('side card preferences', () => {
     expect((await loadPrefs(wire({ interceptOpenPath: true }))).interceptOpenPath).toBe(true)
   })
 
-  it('defaults titleBarCompat to false; only an explicit true turns the position-compat mode on', async () => {
-    // Absent or malformed → off (the normal layout is the default).
-    expect((await loadPrefs(wire({}))).titleBarCompat).toBe(false)
-    expect((await loadPrefs(wire({ titleBarCompat: 'yes' }))).titleBarCompat).toBe(false)
-    expect((await loadPrefs(wire({ titleBarCompat: 1 }))).titleBarCompat).toBe(false)
-    // Explicit booleans survive verbatim.
-    expect((await loadPrefs(wire({ titleBarCompat: false }))).titleBarCompat).toBe(false)
-    expect((await loadPrefs(wire({ titleBarCompat: true }))).titleBarCompat).toBe(true)
-  })
-
   it('defaults the link-takeover protocol flags: http on, https off, master on', async () => {
     // Absent or malformed → the per-protocol defaults.
     expect((await loadPrefs(wire({}))).browserInterceptLinks).toBe(true)
@@ -1286,9 +1273,9 @@ describe('side card preferences', () => {
     const store = createSidebarStore()
     // Node environment: no window → the width falls back to PANEL_DEFAULT,
     // while the open flag still follows the preference.
-    store.setPrefs({ openByDefault: false, defaultWidthPercent: 45, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, titleBarCompat: false, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
+    store.setPrefs({ openByDefault: false, defaultWidthPercent: 45, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
     store.setSession('fresh-session')
-    expect(store.getPrefs()).toEqual({ openByDefault: false, defaultWidthPercent: 45, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, titleBarCompat: false, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
+    expect(store.getPrefs()).toEqual({ openByDefault: false, defaultWidthPercent: 45, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
     const snapshot = store.getSnapshot()
     expect(snapshot.sessionId).toBe('fresh-session')
     expect(snapshot.state?.panelOpen).toBe(false)
@@ -1324,7 +1311,7 @@ describe('side card preferences', () => {
 
   it('skips the default explorer tab when the explorer type is disabled', () => {
     const store = createSidebarStore()
-    store.setPrefs({ openByDefault: true, defaultWidthPercent: 30, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, titleBarCompat: false, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: { explorer: false }, viewersEnabled: {}, pluginSettings: {} })
+    store.setPrefs({ openByDefault: true, defaultWidthPercent: 30, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: { explorer: false }, viewersEnabled: {}, pluginSettings: {} })
     store.setSession('no-explorer')
     const state = store.getSnapshot().state!
     const tabs = allLeaves(state.splits).flatMap(leaf => leaf.tabs)
@@ -1332,7 +1319,7 @@ describe('side card preferences', () => {
     expect(state.splits.kind).toBe('leaf')
     // Re-enabling seeds the explorer tab again.
     const openStore = createSidebarStore()
-    openStore.setPrefs({ openByDefault: true, defaultWidthPercent: 30, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, titleBarCompat: false, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
+    openStore.setPrefs({ openByDefault: true, defaultWidthPercent: 30, autoOpenSubagent: true, autoOpenJobs: true, agentTerminalTools: false, bottomPanelAutoTerminal: true, terminalFontFamily: '', terminalFontSize: 13, interceptOpenPath: true, htmlViewerNoSandbox: false, htmlViewerDefaultUnsafe: false, browserNoSandbox: false, browserInterceptLinks: true, browserInterceptHttp: true, browserInterceptHttps: false, tabsEnabled: {}, viewersEnabled: {}, pluginSettings: {} })
     openStore.setSession('with-explorer')
     const openTabs = allLeaves(openStore.getSnapshot().state!.splits).flatMap(leaf => leaf.tabs)
     expect(openTabs.map(tab => tab.type)).toEqual(['explorer'])