feat(desktop): add a chat backdrop on/off toggle

The faint statue backdrop behind the transcript was only switchable via
the DEV-only leva panel. Add a persisted Appearance toggle (default on)
so users can hide it; the Backdrop simply skips rendering when off.

apps/desktop/src/app/settings/appearance-settings.tsx

@@ -12,6 +12,7 @@ import { Check, Download, Loader2, Palette, Trash2 } from '@/lib/icons'
 import { selectableCardClass } from '@/lib/selectable-card'
 import { normalize } from '@/lib/text'
 import { cn } from '@/lib/utils'
+import { $backdrop, setBackdrop } from '@/store/backdrop'
 import { $embedAllowed, $embedMode, clearEmbedAllowed, type EmbedMode, setEmbedMode } from '@/store/embed-consent'
 import { $activeGatewayProfile, $profiles, normalizeProfileKey } from '@/store/profile'
 import { $toolViewMode, setToolViewMode } from '@/store/tool-view'
@@ -248,6 +249,7 @@ export function AppearanceSettings() {
   const embedMode = useStore($embedMode)
   const embedAllowed = useStore($embedAllowed)
   const translucency = useStore($translucency)
+  const backdrop = useStore($backdrop)
   const installs = useStore($marketplaceInstalls)
   const profiles = useStore($profiles)
   const activeProfileKey = normalizeProfileKey(useStore($activeGatewayProfile))
@@ -451,6 +453,24 @@ export function AppearanceSettings() {
             title={a.translucencyTitle}
           />
 
+          <ListRow
+            action={
+              <SegmentedControl
+                onChange={id => {
+                  triggerHaptic('selection')
+                  setBackdrop(id === 'on')
+                }}
+                options={[
+                  { id: 'off', label: t.common.off },
+                  { id: 'on', label: t.common.on }
+                ]}
+                value={backdrop ? 'on' : 'off'}
+              />
+            }
+            description={a.backdropDesc}
+            title={a.backdropTitle}
+          />
+
           <ListRow
             action={
               <SegmentedControl

apps/desktop/src/components/Backdrop.tsx

@@ -1,6 +1,9 @@
+import { useStore } from '@nanostores/react'
 import { Leva, useControls } from 'leva'
 import { type CSSProperties, useEffect, useState } from 'react'
 
+import { $backdrop } from '@/store/backdrop'
+
 const BLEND_MODES = [
   'normal',
   'multiply',
@@ -25,6 +28,7 @@ const assetPath = (path: string) => `${import.meta.env.BASE_URL}${path.replace(/
 
 export function Backdrop() {
   const [controlsOpen, setControlsOpen] = useState(false)
+  const on = useStore($backdrop)
 
   useEffect(() => {
     if (!import.meta.env.DEV) {
@@ -87,7 +91,7 @@ export function Backdrop() {
     <>
       <Leva collapsed hidden={!import.meta.env.DEV || !controlsOpen} titleBar={{ title: 'backdrop', drag: true }} />
 
-      {statue.enabled && (
+      {on && statue.enabled && (
         <div
           aria-hidden
           className="pointer-events-none absolute inset-0 z-2"

apps/desktop/src/i18n/en.ts

@@ -392,6 +392,8 @@ export const en: Translations = {
         `Scales text and controls across the whole app. Cmd/Ctrl with +, - and 0 also works. Current: ${percent}%.`,
       translucencyTitle: 'Window Translucency',
       translucencyDesc: 'See your desktop through the whole window. macOS and Windows only.',
+      backdropTitle: 'Chat Backdrop',
+      backdropDesc: 'The faint statue image behind the conversation.',
       embedsTitle: 'Inline Embeds',
       embedsDesc:
         'Rich previews load from third-party sites (YouTube, X, …). Ask shows a placeholder until you allow each one; Always loads them automatically; Off keeps plain links.',

apps/desktop/src/i18n/ja.ts

@@ -297,6 +297,8 @@ export const ja = defineLocale({
         `アプリ全体の文字と UI を拡大縮小します。Cmd/Ctrl と +、-、0 でも変更できます。現在: ${percent}%`,
       translucencyTitle: 'ウィンドウの透過',
       translucencyDesc: 'ウィンドウ全体を透過させてデスクトップを表示します。macOS と Windows のみ。',
+      backdropTitle: 'チャット背景',
+      backdropDesc: '会話の背後に表示される淡い彫像の画像。',
       embedsTitle: 'インライン埋め込み',
       embedsDesc:
         'リッチプレビューは第三者サイト（YouTube、X など）から読み込まれます。確認は許可するまでプレースホルダーを表示し、常には自動で読み込み、オフはリンクのままにします。',

apps/desktop/src/i18n/types.ts

@@ -311,6 +311,8 @@ export interface Translations {
       uiScaleDesc: (percent: number) => string
       translucencyTitle: string
       translucencyDesc: string
+      backdropTitle: string
+      backdropDesc: string
       embedsTitle: string
       embedsDesc: string
       embedsAsk: string

apps/desktop/src/i18n/zh-hant.ts

@@ -290,6 +290,8 @@ export const zhHant = defineLocale({
         `縮放整個應用程式的文字與介面。也可使用 Cmd/Ctrl 加 +、- 或 0 調整。目前：${percent}%`,
       translucencyTitle: '視窗透明',
       translucencyDesc: '讓整個視窗透出桌面。僅支援 macOS 與 Windows。',
+      backdropTitle: '聊天背景',
+      backdropDesc: '對話後方那張淡淡的雕像圖片。',
       embedsTitle: '內嵌預覽',
       embedsDesc:
         '豐富預覽會從第三方網站（YouTube、X 等）載入。詢問會在你允許前顯示佔位符；一律會自動載入；關閉則保留純連結。',

apps/desktop/src/i18n/zh.ts

@@ -381,6 +381,8 @@ export const zh: Translations = {
         `缩放整个应用的文字和界面。也可使用 Cmd/Ctrl 加 +、- 或 0 调整。当前：${percent}%`,
       translucencyTitle: '窗口透明',
       translucencyDesc: '让整个窗口透出桌面。仅支持 macOS 和 Windows。',
+      backdropTitle: '聊天背景',
+      backdropDesc: '对话后方那张淡淡的雕像图片。',
       embedsTitle: '内嵌预览',
       embedsDesc:
         '富预览会从第三方网站（YouTube、X 等）加载。询问会在你允许前显示占位符；总是会自动加载；关闭则保留纯链接。',

apps/desktop/src/store/backdrop.ts

@@ -0,0 +1,21 @@
+/**
+ * Chat backdrop image (the faint statue behind the transcript). One boolean,
+ * on by default. Purely presentational renderer state — the `Backdrop`
+ * component just skips rendering when it's off.
+ */
+
+import { atom } from 'nanostores'
+
+import { persistBoolean, storedBoolean } from '@/lib/storage'
+
+const KEY = 'hermes.desktop.backdrop.v1'
+
+export const $backdrop = atom<boolean>(typeof window === 'undefined' ? true : storedBoolean(KEY, true))
+
+export function setBackdrop(on: boolean): void {
+  $backdrop.set(on)
+}
+
+if (typeof window !== 'undefined') {
+  $backdrop.subscribe(on => persistBoolean(KEY, on))
+}