diff --git a/openless-all/app/src/i18n/en.ts b/openless-all/app/src/i18n/en.ts
index 30843cd9..fd2ad82d 100644
--- a/openless-all/app/src/i18n/en.ts
+++ b/openless-all/app/src/i18n/en.ts
@@ -186,6 +186,7 @@ export const en: typeof zhCN = {
     masterToggle: 'Master switch',
     currentDefault: 'Current default',
     ariaSetDefault: 'Set as default',
+    saveFailed: 'Save failed: {{error}}',
     modes: {
       raw: { name: 'Raw', desc: 'Only adds punctuation and natural breaks — no rewriting or expansion.', sample: "Keeps spoken cadence; fillers like 'um' or 'you know' get dropped, but sentences stay intact." },
       light: { name: 'Light polish', desc: 'Drops fillers, adds punctuation, and produces sendable natural prose.', sample: "Makes the transcript flow well without sounding scripted — your tone and habits remain." },
diff --git a/openless-all/app/src/i18n/ja.ts b/openless-all/app/src/i18n/ja.ts
index 27790919..4b37da84 100644
--- a/openless-all/app/src/i18n/ja.ts
+++ b/openless-all/app/src/i18n/ja.ts
@@ -188,6 +188,7 @@ export const ja: typeof zhCN = {
     masterToggle: '全体有効化',
     currentDefault: '現在のデフォルト',
     ariaSetDefault: 'デフォルトに設定',
+    saveFailed: '保存に失敗しました: {{error}}',
     modes: {
       raw: { name: '原文', desc: '句読点と必要な区切りのみ補い、書き換えや拡張はしません。', sample: '元の話し言葉を保持。「えー」「あの」などの口癖は除去しますが、文の組み替えはしません。' },
       light: { name: '軽い整文', desc: '口癖の除去、句読点の補完、自然な送信可能テキストへの整理。', sample: '原稿読み上げのようにならないよう、語気と表現の癖を残しつつ、文章をなめらかにします。' },
diff --git a/openless-all/app/src/i18n/ko.ts b/openless-all/app/src/i18n/ko.ts
index a517a03f..052832ef 100644
--- a/openless-all/app/src/i18n/ko.ts
+++ b/openless-all/app/src/i18n/ko.ts
@@ -188,6 +188,7 @@ export const ko: typeof zhCN = {
     masterToggle: '전체 활성화',
     currentDefault: '현재 기본',
     ariaSetDefault: '기본으로 설정',
+    saveFailed: '저장 실패: {{error}}',
     modes: {
       raw: { name: '원문', desc: '구두점과 필요한 문장 구분만 보충하고 다시 쓰거나 확장하지 않습니다.', sample: '원래 구어체 유지. "음", "그게" 같은 입버릇은 제거하지만 문장을 재구성하지 않습니다.' },
       light: { name: '가벼운 정리', desc: '입버릇 제거, 구두점 보충, 자연스럽게 보낼 수 있는 텍스트로 정리합니다.', sample: '원고를 읽는 듯한 느낌이 들지 않도록 어조와 표현 습관은 남기되, 문장이 매끄럽게 흐르도록 합니다.' },
diff --git a/openless-all/app/src/i18n/zh-CN.ts b/openless-all/app/src/i18n/zh-CN.ts
index db99cebc..7dc1c2d5 100644
--- a/openless-all/app/src/i18n/zh-CN.ts
+++ b/openless-all/app/src/i18n/zh-CN.ts
@@ -184,6 +184,7 @@ export const zhCN = {
     masterToggle: '整体启用',
     currentDefault: '当前默认',
     ariaSetDefault: '设为默认',
+    saveFailed: '保存失败：{{error}}',
     modes: {
       raw: { name: '原文', desc: '只补标点和必要分句，不改写不扩写。', sample: '保留原始口语；嗯、那个等口癖会被去除，但不会重组语句。' },
       light: { name: '轻度润色', desc: '去口癖、补标点，整理为可发送的自然文字。', sample: '让转写听起来不像念稿——保留语气和表达习惯，但行文流畅。' },
diff --git a/openless-all/app/src/i18n/zh-TW.ts b/openless-all/app/src/i18n/zh-TW.ts
index e457f8cb..75e4af24 100644
--- a/openless-all/app/src/i18n/zh-TW.ts
+++ b/openless-all/app/src/i18n/zh-TW.ts
@@ -186,6 +186,7 @@ export const zhTW: typeof zhCN = {
     masterToggle: '整體啓用',
     currentDefault: '當前默認',
     ariaSetDefault: '設爲默認',
+    saveFailed: '保存失敗：{{error}}',
     modes: {
       raw: { name: '原文', desc: '只補標點和必要分句，不改寫不擴寫。', sample: '保留原始口語；嗯、那個等口癖會被去除，但不會重組語句。' },
       light: { name: '輕度潤色', desc: '去口癖、補標點，整理爲可發送的自然文字。', sample: '讓轉寫聽起來不像念稿——保留語氣和表達習慣，但行文流暢。' },
diff --git a/openless-all/app/src/lib/stylePrefs.test.ts b/openless-all/app/src/lib/stylePrefs.test.ts
new file mode 100644
index 00000000..02eb50fd
--- /dev/null
+++ b/openless-all/app/src/lib/stylePrefs.test.ts
@@ -0,0 +1,103 @@
+import {
+  persistStylePreferenceChange,
+  rollbackStyleEnabledChange,
+  rollbackWholeStylePreferences,
+} from './stylePrefs';
+import type { UserPreferences } from './types';
+
+function assert(condition: boolean, message: string) {
+  if (!condition) throw new Error(message);
+}
+
+const previousPrefs: UserPreferences = {
+  hotkey: { trigger: 'rightOption', mode: 'toggle' },
+  dictationHotkey: { primary: 'RightOption', modifiers: [] },
+  defaultMode: 'light',
+  enabledModes: ['raw', 'light', 'structured'],
+  launchAtLogin: false,
+  showCapsule: true,
+  muteDuringRecording: false,
+  microphoneDeviceName: '',
+  activeAsrProvider: 'volcengine',
+  activeLlmProvider: 'ark',
+  restoreClipboardAfterPaste: true,
+  allowNonTsfInsertionFallback: true,
+  workingLanguages: ['简体中文'],
+  translationTargetLanguage: '',
+  chineseScriptPreference: 'auto',
+  outputLanguagePreference: 'auto',
+  qaHotkey: null,
+  qaSaveHistory: false,
+  customComboHotkey: null,
+  translationHotkey: { primary: 'Shift', modifiers: [] },
+  switchStyleHotkey: { primary: 'S', modifiers: ['alt'] },
+  openAppHotkey: { primary: 'O', modifiers: ['alt'] },
+  localAsrActiveModel: '',
+  localAsrMirror: 'huggingface',
+  localAsrKeepLoadedSecs: 300,
+  foundryLocalAsrModel: '',
+  foundryLocalAsrLanguageHint: '',
+  foundryLocalAsrKeepLoadedSecs: 300,
+};
+
+const nextPrefs: UserPreferences = {
+  ...previousPrefs,
+  enabledModes: [],
+};
+
+const states: UserPreferences[] = [];
+const errors: string[] = [];
+let firstCurrentPrefs: UserPreferences | null = previousPrefs;
+const saved = await persistStylePreferenceChange(
+  nextPrefs,
+  async () => {
+    throw 'disk full';
+  },
+  update => {
+    firstCurrentPrefs = typeof update === 'function' ? update(firstCurrentPrefs) : update;
+    if (firstCurrentPrefs) states.push(firstCurrentPrefs);
+  },
+  message => errors.push(message),
+  rollbackWholeStylePreferences(previousPrefs, nextPrefs),
+);
+
+assert(saved === false, 'setSettings reject should report save failure');
+assert(states.length === 2, `expected optimistic state then rollback, got ${states.length} updates`);
+assert(states[0] === nextPrefs, 'first state update should be the optimistic next prefs');
+assert(
+  states[1].enabledModes.join(',') === previousPrefs.enabledModes.join(','),
+  'second state update should roll back enabled modes to previous prefs',
+);
+assert(errors[0] === 'disk full', `expected backend error message, got ${errors[0]}`);
+
+let currentPrefs: UserPreferences | null = previousPrefs;
+const disableLightPrefs: UserPreferences = {
+  ...previousPrefs,
+  enabledModes: ['raw', 'structured'],
+};
+const disableStructuredAfterLightPrefs: UserPreferences = {
+  ...previousPrefs,
+  enabledModes: ['raw'],
+};
+const overlapSaved = await persistStylePreferenceChange(
+  disableLightPrefs,
+  async () => {
+    currentPrefs = disableStructuredAfterLightPrefs;
+    throw 'slow failure';
+  },
+  update => {
+    currentPrefs = typeof update === 'function' ? update(currentPrefs) : update;
+  },
+  () => undefined,
+  rollbackStyleEnabledChange('light', previousPrefs, disableLightPrefs),
+);
+
+assert(overlapSaved === false, 'overlapped style save should still report failure');
+assert(
+  currentPrefs?.enabledModes.includes('light') === true,
+  'failed light toggle should roll back only the light mode',
+);
+assert(
+  currentPrefs?.enabledModes.includes('structured') === false,
+  'failed light toggle should preserve newer structured edit',
+);
diff --git a/openless-all/app/src/lib/stylePrefs.ts b/openless-all/app/src/lib/stylePrefs.ts
new file mode 100644
index 00000000..96cc8d70
--- /dev/null
+++ b/openless-all/app/src/lib/stylePrefs.ts
@@ -0,0 +1,70 @@
+import type { PolishMode, UserPreferences } from './types';
+
+type StylePrefsState = UserPreferences | null;
+type StylePrefsSetter = (prefs: StylePrefsState | ((current: StylePrefsState) => StylePrefsState)) => void;
+type StylePrefsRollback = (current: StylePrefsState) => StylePrefsState;
+
+export function styleSaveErrorMessage(error: unknown): string {
+  if (error instanceof Error) return error.message;
+  if (typeof error === 'string') return error;
+  return String(error);
+}
+
+export async function persistStylePreferenceChange(
+  nextPrefs: UserPreferences,
+  persist: () => Promise<void>,
+  setPrefs: StylePrefsSetter,
+  onFailure: (message: string) => void,
+  rollback: StylePrefsRollback,
+): Promise<boolean> {
+  setPrefs(nextPrefs);
+  try {
+    await persist();
+    return true;
+  } catch (error) {
+    setPrefs(current => rollback(current));
+    onFailure(styleSaveErrorMessage(error));
+    return false;
+  }
+}
+
+export function rollbackDefaultModeChange(
+  previousPrefs: UserPreferences,
+  nextPrefs: UserPreferences,
+): StylePrefsRollback {
+  return current => {
+    if (!current || current.defaultMode !== nextPrefs.defaultMode) return current;
+    return { ...current, defaultMode: previousPrefs.defaultMode };
+  };
+}
+
+export function rollbackStyleEnabledChange(
+  mode: PolishMode,
+  previousPrefs: UserPreferences,
+  nextPrefs: UserPreferences,
+): StylePrefsRollback {
+  const previousEnabled = previousPrefs.enabledModes.includes(mode);
+  const nextEnabled = nextPrefs.enabledModes.includes(mode);
+  return current => {
+    if (!current || current.enabledModes.includes(mode) !== nextEnabled) return current;
+    const enabledModes = previousEnabled
+      ? Array.from(new Set([...current.enabledModes, mode]))
+      : current.enabledModes.filter(m => m !== mode);
+    return { ...current, enabledModes };
+  };
+}
+
+export function rollbackWholeStylePreferences(
+  previousPrefs: UserPreferences,
+  nextPrefs: UserPreferences,
+): StylePrefsRollback {
+  return current => {
+    if (!current || !sameModes(current.enabledModes, nextPrefs.enabledModes)) return current;
+    return { ...current, enabledModes: previousPrefs.enabledModes };
+  };
+}
+
+function sameModes(left: PolishMode[], right: PolishMode[]): boolean {
+  if (left.length !== right.length) return false;
+  return left.every((mode, index) => mode === right[index]);
+}
diff --git a/openless-all/app/src/pages/Style.tsx b/openless-all/app/src/pages/Style.tsx
index f53497da..1a78948b 100644
--- a/openless-all/app/src/pages/Style.tsx
+++ b/openless-all/app/src/pages/Style.tsx
@@ -5,6 +5,12 @@ import { useEffect, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { getSettings, setDefaultPolishMode, setStyleEnabled, setSettings } from '../lib/ipc';
 import type { PolishMode, UserPreferences } from '../lib/types';
+import {
+  persistStylePreferenceChange,
+  rollbackDefaultModeChange,
+  rollbackStyleEnabledChange,
+  rollbackWholeStylePreferences,
+} from '../lib/stylePrefs';
 import { PageHeader, Pill } from './_atoms';
 
 interface StyleDef {
@@ -15,6 +21,7 @@ interface StyleDef {
 }
 
 const STYLE_IDS: PolishMode[] = ['raw', 'light', 'structured', 'formal'];
+type StyleSaveErrorTarget = PolishMode | 'master';
 
 export function Style() {
   const { t } = useTranslation();
@@ -25,15 +32,27 @@ export function Style() {
     sample: t(`style.modes.${id}.sample`),
   }));
   const [prefs, setPrefs] = useState<UserPreferences | null>(null);
+  const [saveError, setSaveError] = useState<{ target: StyleSaveErrorTarget; message: string } | null>(null);
 
   useEffect(() => {
     getSettings().then(setPrefs);
   }, []);
 
+  const showSaveError = (target: StyleSaveErrorTarget, error: string) => {
+    setSaveError({ target, message: t('style.saveFailed', { error }) });
+  };
+
   const onPickDefault = async (mode: PolishMode) => {
     if (!prefs) return;
-    setPrefs({ ...prefs, defaultMode: mode });
-    await setDefaultPolishMode(mode);
+    const next = { ...prefs, defaultMode: mode };
+    const saved = await persistStylePreferenceChange(
+      next,
+      () => setDefaultPolishMode(mode),
+      setPrefs,
+      error => showSaveError(mode, error),
+      rollbackDefaultModeChange(prefs, next),
+    );
+    if (saved) setSaveError(null);
   };
 
   const onToggleEnabled = async (mode: PolishMode) => {
@@ -42,8 +61,15 @@ export function Style() {
     const nextEnabled = enabled
       ? [...prefs.enabledModes, mode]
       : prefs.enabledModes.filter(m => m !== mode);
-    setPrefs({ ...prefs, enabledModes: nextEnabled });
-    await setStyleEnabled(mode, enabled);
+    const next = { ...prefs, enabledModes: nextEnabled };
+    const saved = await persistStylePreferenceChange(
+      next,
+      () => setStyleEnabled(mode, enabled),
+      setPrefs,
+      error => showSaveError(mode, error),
+      rollbackStyleEnabledChange(mode, prefs, next),
+    );
+    if (saved) setSaveError(null);
   };
 
   if (!prefs) {
@@ -63,12 +89,24 @@ export function Style() {
     if (masterEnabled) {
       // 全部关闭 → 留 raw 和当前 default 兜底
       const next = { ...prefs, enabledModes: [] as PolishMode[] };
-      setPrefs(next);
-      await setSettings(next);
+      const saved = await persistStylePreferenceChange(
+        next,
+        () => setSettings(next),
+        setPrefs,
+        error => showSaveError('master', error),
+        rollbackWholeStylePreferences(prefs, next),
+      );
+      if (saved) setSaveError(null);
     } else {
       const next = { ...prefs, enabledModes: ['raw', 'light', 'structured', 'formal'] as PolishMode[] };
-      setPrefs(next);
-      await setSettings(next);
+      const saved = await persistStylePreferenceChange(
+        next,
+        () => setSettings(next),
+        setPrefs,
+        error => showSaveError('master', error),
+        rollbackWholeStylePreferences(prefs, next),
+      );
+      if (saved) setSaveError(null);
     }
   };
 
@@ -97,6 +135,14 @@ export function Style() {
                 }}
               />
             </button>
+            {saveError?.target === 'master' && (
+              <span
+                role="alert"
+                style={{ fontSize: 11.5, color: 'var(--ol-red, #ef4444)', maxWidth: 220, lineHeight: 1.45 }}
+              >
+                {saveError.message}
+              </span>
+            )}
           </div>
         }
       />
@@ -176,6 +222,14 @@ export function Style() {
               >
                 {s.sample}
               </div>
+              {saveError?.target === s.id && (
+                <div
+                  role="alert"
+                  style={{ marginTop: 10, fontSize: 11.5, color: 'var(--ol-red, #ef4444)', lineHeight: 1.45 }}
+                >
+                  {saveError.message}
+                </div>
+              )}
             </div>
           );
         })}