diff --git a/desktop/src/components/layout/Sidebar.test.tsx b/desktop/src/components/layout/Sidebar.test.tsx
index c7c568b9..8d9bff1b 100644
--- a/desktop/src/components/layout/Sidebar.test.tsx
+++ b/desktop/src/components/layout/Sidebar.test.tsx
@@ -35,10 +35,6 @@ vi.mock('../../i18n', () => ({
       'sidebar.noMatching': 'No matching sessions',
       'sidebar.sessionListFailed': 'Session list failed',
       'sidebar.refreshSessions': 'Refresh sessions',
-      'sidebar.indexBuilding': 'Optimizing history',
-      'sidebar.indexBuildingProgress': 'Optimizing history {indexed}/{discovered}',
-      'sidebar.indexReady': 'History optimization complete',
-      'sidebar.indexOff': 'History optimization inactive',
       'sidebar.indexDegraded': 'Using standard history loading',
       'search.global.trigger': 'Search chats',
       'sidebar.projects': 'Projects',
@@ -1294,7 +1290,9 @@ describe('Sidebar', () => {
     expect(screen.queryByText('No sessions')).not.toBeInTheDocument()
   })
 
-  it('shows quiet building progress while keeping indexed rows visible', () => {
+  // Indexing is background housekeeping the user cannot act on, so a partially
+  // built index must look exactly like a finished one: rows visible, no counter.
+  it('keeps indexed rows visible while building without surfacing progress', () => {
     useSessionStore.setState({
       sessions: [makeSession('indexed-row', 'Indexed row', '/workspace/alpha', '2026-07-15T00:00:00.000Z')],
       indexStatus: {
@@ -1313,7 +1311,9 @@ describe('Sidebar', () => {
     render(<Sidebar />)
 
     expect(screen.getByRole('button', { name: /Indexed row/ })).toBeInTheDocument()
-    expect(screen.getByTestId('sidebar-index-progress')).toHaveTextContent('Optimizing history 2/10')
+    expect(screen.queryByTestId('sidebar-index-progress')).not.toBeInTheDocument()
+    expect(screen.queryByText(/2\s*\/\s*10/)).not.toBeInTheDocument()
+    expect(screen.getByRole('status')).toBeEmptyDOMElement()
   })
 
   it.each(['ready', 'off'] as const)('hides visible index status when state is %s', (state) => {
@@ -1565,14 +1565,17 @@ describe('Sidebar', () => {
     }
   })
 
-  it('announces state transitions without exposing numeric progress to the live region', () => {
+  // The live region exists for the one transition a user can perceive: history
+  // is being served the slow way. Building/ready/off are silent there too, so a
+  // screen reader is not told about work that needs no reaction.
+  it.each(['building', 'ready', 'off'] as const)('stays silent in the live region while %s', (state) => {
     useSessionStore.setState({
       sessions: [makeSession('live-row', 'Live row', '/workspace/alpha', '2026-07-15T00:00:00.000Z')],
       indexStatus: {
-        mode: 'on',
-        state: 'building',
+        mode: state === 'off' ? 'off' : 'on',
+        state,
         discovered: 10,
-        indexed: 2,
+        indexed: state === 'building' ? 2 : 10,
         degradedSources: 0,
         databaseBytes: 4096,
         walBytes: 0,
@@ -1583,10 +1586,31 @@ describe('Sidebar', () => {
 
     render(<Sidebar />)
 
+    expect(screen.getByRole('status')).toBeEmptyDOMElement()
+  })
+
+  it('announces the degraded fallback in the live region', () => {
+    useSessionStore.setState({
+      sessions: [makeSession('live-row', 'Live row', '/workspace/alpha', '2026-07-15T00:00:00.000Z')],
+      indexStatus: {
+        mode: 'on',
+        state: 'degraded',
+        discovered: 10,
+        indexed: 2,
+        degradedSources: 1,
+        databaseBytes: 4096,
+        walBytes: 0,
+        lastUpdatedAt: '2026-07-15T00:00:00.000Z',
+        lastErrorCode: 'source_unreadable',
+      },
+    })
+
+    render(<Sidebar />)
+
     const liveRegion = screen.getByRole('status')
-    expect(liveRegion).toHaveTextContent('Optimizing history')
+    expect(liveRegion).toHaveTextContent('Using standard history loading')
     expect(liveRegion).not.toHaveTextContent('2/10')
-    expect(screen.getByTestId('sidebar-index-progress')).toHaveAttribute('aria-hidden', 'true')
+    expect(screen.getByTestId('sidebar-index-degraded')).toHaveAttribute('aria-hidden', 'true')
   })
 
   it('refreshes sessions manually and through low-frequency visible polling', async () => {
diff --git a/desktop/src/components/layout/Sidebar.tsx b/desktop/src/components/layout/Sidebar.tsx
index 60509962..01ac60e6 100644
--- a/desktop/src/components/layout/Sidebar.tsx
+++ b/desktop/src/components/layout/Sidebar.tsx
@@ -190,17 +190,12 @@ export function Sidebar({ isMobile = false, onRequestClose }: SidebarProps) {
   }, [hiddenProjectKeys, orderedProjectGroups])
   const showInitialLoading = isLoading && sessions.length === 0
   const showRefreshLoading = showInitialLoading
-  const showIndexBuilding = indexStatus?.state === 'building' && sessions.length > 0
+  // Index building/ready/off are implementation details of how the list is
+  // loaded, not something the user acts on, so they stay silent in both the
+  // visible sidebar and the live region. Only `degraded` is announced: there
+  // the list really is served a different way, which the user can perceive.
   const showIndexDegraded = indexStatus?.state === 'degraded'
-  const indexAnnouncement = indexStatus
-    ? t(indexStatus.state === 'building'
-      ? 'sidebar.indexBuilding'
-      : indexStatus.state === 'ready'
-        ? 'sidebar.indexReady'
-        : indexStatus.state === 'degraded'
-          ? 'sidebar.indexDegraded'
-          : 'sidebar.indexOff')
-    : ''
+  const indexAnnouncement = showIndexDegraded ? t('sidebar.indexDegraded') : ''
   const filteredSessionIds = useMemo(() => filteredSessions.map((session) => session.id), [filteredSessions])
   const selectedCount = selectedSessionIds.size
   const sessionsById = useMemo(
@@ -889,18 +884,6 @@ export function Sidebar({ isMobile = false, onRequestClose }: SidebarProps) {
             <div role="status" aria-live="polite" aria-atomic="true" className="sr-only">
               {indexAnnouncement}
             </div>
-            {showIndexBuilding && (
-              <div
-                data-testid="sidebar-index-progress"
-                aria-hidden="true"
-                className="mx-4 mb-1 flex-none text-[11px] leading-5 text-[var(--color-text-tertiary)]"
-              >
-                {t('sidebar.indexBuildingProgress', {
-                  indexed: indexStatus.indexed,
-                  discovered: indexStatus.discovered,
-                })}
-              </div>
-            )}
             {showIndexDegraded && (
               <div
                 data-testid="sidebar-index-degraded"
diff --git a/desktop/src/i18n/index.test.tsx b/desktop/src/i18n/index.test.tsx
index ec06e5d7..962ad24e 100644
--- a/desktop/src/i18n/index.test.tsx
+++ b/desktop/src/i18n/index.test.tsx
@@ -77,4 +77,16 @@ describe('useTranslation', () => {
       expect(resurrected, `${name} still defines removed installed-skills keys`).toEqual([])
     }
   })
+
+  // Index building/ready/off went silent: the sidebar no longer tells anyone
+  // that history is being indexed. Keeping the strings around invites a future
+  // change to wire them back into the UI, so they must stay deleted.
+  it('carries no key for the silent index states', () => {
+    for (const [name, locale] of Object.entries(locales)) {
+      const resurrected = Object.keys(locale).filter(
+        key => key.startsWith('sidebar.index') && key !== 'sidebar.indexDegraded',
+      )
+      expect(resurrected, `${name} still defines silent index-status keys`).toEqual([])
+    }
+  })
 })
diff --git a/desktop/src/i18n/locales/en.ts b/desktop/src/i18n/locales/en.ts
index b6aee775..ca5f5102 100644
--- a/desktop/src/i18n/locales/en.ts
+++ b/desktop/src/i18n/locales/en.ts
@@ -48,10 +48,6 @@ export const en = {
   'sidebar.noMatching': 'No matching sessions',
   'sidebar.sessionListFailed': 'Session list failed to load',
   'sidebar.refreshSessions': 'Refresh sessions',
-  'sidebar.indexBuilding': 'Optimizing history',
-  'sidebar.indexBuildingProgress': 'Optimizing history {indexed}/{discovered}',
-  'sidebar.indexReady': 'History optimization complete',
-  'sidebar.indexOff': 'History optimization inactive',
   'sidebar.indexDegraded': 'Using standard history loading',
   'search.global.trigger': 'Search chats',
   'search.global.placeholder': 'Search all chats…',
diff --git a/desktop/src/i18n/locales/jp.ts b/desktop/src/i18n/locales/jp.ts
index 6d2d96db..7f1776ea 100644
--- a/desktop/src/i18n/locales/jp.ts
+++ b/desktop/src/i18n/locales/jp.ts
@@ -50,10 +50,6 @@ export const jp: Record<TranslationKey, string> = {
   'sidebar.noMatching': '一致するセッションがありません',
   'sidebar.sessionListFailed': 'セッション一覧の読み込みに失敗しました',
   'sidebar.refreshSessions': 'セッションを更新',
-  'sidebar.indexBuilding': '履歴を最適化しています',
-  'sidebar.indexBuildingProgress': '履歴を最適化しています {indexed}/{discovered}',
-  'sidebar.indexReady': '履歴の最適化が完了しました',
-  'sidebar.indexOff': '履歴の最適化は無効です',
   'sidebar.indexDegraded': '標準の履歴読み込みを使用しています',
   'search.global.trigger': 'チャットを検索',
   'search.global.placeholder': 'すべてのチャットを検索…',
diff --git a/desktop/src/i18n/locales/kr.ts b/desktop/src/i18n/locales/kr.ts
index bdbe8ee4..36951047 100644
--- a/desktop/src/i18n/locales/kr.ts
+++ b/desktop/src/i18n/locales/kr.ts
@@ -50,10 +50,6 @@ export const kr: Record<TranslationKey, string> = {
   'sidebar.noMatching': '일치하는 세션이 없습니다',
   'sidebar.sessionListFailed': '세션 목록을 불러오지 못했습니다',
   'sidebar.refreshSessions': '세션 새로 고침',
-  'sidebar.indexBuilding': '기록을 최적화하는 중',
-  'sidebar.indexBuildingProgress': '기록을 최적화하는 중 {indexed}/{discovered}',
-  'sidebar.indexReady': '기록 최적화가 완료되었습니다',
-  'sidebar.indexOff': '기록 최적화가 비활성화되었습니다',
   'sidebar.indexDegraded': '표준 기록 불러오기를 사용하고 있습니다',
   'search.global.trigger': '대화 검색',
   'search.global.placeholder': '모든 대화 검색…',
diff --git a/desktop/src/i18n/locales/zh-TW.ts b/desktop/src/i18n/locales/zh-TW.ts
index 40f3ea89..d262e0d2 100644
--- a/desktop/src/i18n/locales/zh-TW.ts
+++ b/desktop/src/i18n/locales/zh-TW.ts
@@ -50,10 +50,6 @@ export const zh: Record<TranslationKey, string> = {
   'sidebar.noMatching': '沒有匹配的會話',
   'sidebar.sessionListFailed': '會話列表載入失敗',
   'sidebar.refreshSessions': '重新整理會話列表',
-  'sidebar.indexBuilding': '正在最佳化歷史記錄',
-  'sidebar.indexBuildingProgress': '正在最佳化歷史記錄 {indexed}/{discovered}',
-  'sidebar.indexReady': '歷史記錄最佳化完成',
-  'sidebar.indexOff': '歷史記錄最佳化未啟用',
   'sidebar.indexDegraded': '正在使用標準歷史記錄載入',
   'search.global.trigger': '搜尋聊天',
   'search.global.placeholder': '搜尋全部聊天內容…',
diff --git a/desktop/src/i18n/locales/zh.ts b/desktop/src/i18n/locales/zh.ts
index 24619e52..41e5416c 100644
--- a/desktop/src/i18n/locales/zh.ts
+++ b/desktop/src/i18n/locales/zh.ts
@@ -50,10 +50,6 @@ export const zh: Record<TranslationKey, string> = {
   'sidebar.noMatching': '没有匹配的会话',
   'sidebar.sessionListFailed': '会话列表加载失败',
   'sidebar.refreshSessions': '刷新会话列表',
-  'sidebar.indexBuilding': '正在优化历史记录',
-  'sidebar.indexBuildingProgress': '正在优化历史记录 {indexed}/{discovered}',
-  'sidebar.indexReady': '历史记录优化完成',
-  'sidebar.indexOff': '历史记录优化未启用',
   'sidebar.indexDegraded': '正在使用标准历史记录加载',
   'search.global.trigger': '搜索聊天',
   'search.global.placeholder': '搜索全部聊天内容…',