diff --git a/frontend/index.html b/frontend/index.html
index ee5d5e43..2381f26b 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -205,6 +205,40 @@
     #root-seo { visibility: hidden; position: absolute; pointer-events: none; }
   </style>
   <body style="margin:0;background:#1e1e1e;">
+    <!--
+      Desktop-only splash. Sidecar boot + Monaco hydration take 3-8s
+      on a cold launch; without this the user stares at a black window.
+      Hidden by default and revealed by the inline script below only
+      when window.__TAURI__ is present (Tauri webview), so web users
+      never see it. Removed from the DOM when React's first render
+      lands (main.tsx).
+
+      Self-contained: inline SVG logo + CSS keyframes, no external
+      requests. Safe to keep in OSS since the gate is the Tauri
+      global, not VITE_DESKTOP.
+    -->
+    <div id="velxio-splash" aria-hidden="true" style="display:none;position:fixed;inset:0;z-index:2147483647;background:linear-gradient(160deg,#0d1117 0%,#161b22 50%,#0d1117 100%);color:#e6edf3;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;align-items:center;justify-content:center;flex-direction:column;gap:24px;">
+      <svg width="96" height="96" viewBox="0 0 24 24" fill="none" stroke="#58a6ff" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" style="filter:drop-shadow(0 0 18px rgba(88,166,255,0.35));">
+        <rect x="5" y="5" width="14" height="14" rx="2"></rect>
+        <rect x="9" y="9" width="6" height="6"></rect>
+        <path d="M9 1v4M15 1v4M9 19v4M15 19v4M1 9h4M1 15h4M19 9h4M19 15h4"></path>
+      </svg>
+      <div style="font-size:32px;font-weight:600;letter-spacing:0.5px;">Velxio</div>
+      <div style="font-size:14px;color:#8b949e;max-width:340px;text-align:center;line-height:1.5;">Offline Arduino, RP2040 &amp; ESP32 simulator</div>
+      <div style="width:32px;height:32px;border:3px solid rgba(88,166,255,0.18);border-top-color:#58a6ff;border-radius:50%;animation:velxio-spin 0.9s linear infinite;margin-top:8px;"></div>
+      <div style="position:absolute;bottom:24px;left:0;right:0;text-align:center;font-size:11px;color:#484f58;">Starting local backend…</div>
+      <style>@keyframes velxio-spin{to{transform:rotate(360deg)}}</style>
+    </div>
+    <script>
+      // Reveal the splash ONLY inside Tauri. Detection is synchronous:
+      // `withGlobalTauri: true` in tauri.conf.json injects __TAURI__
+      // before page JS runs. Web users land here with __TAURI__
+      // undefined and the splash stays display:none.
+      if (typeof window !== 'undefined' && window.__TAURI__) {
+        var s = document.getElementById('velxio-splash');
+        if (s) s.style.display = 'flex';
+      }
+    </script>
     <div id="root"></div>
     <!--
       Static pre-rendered content for search engine crawlers.
diff --git a/frontend/src/components/layout/AppHeader.tsx b/frontend/src/components/layout/AppHeader.tsx
index fd4c49b8..8a02e067 100644
--- a/frontend/src/components/layout/AppHeader.tsx
+++ b/frontend/src/components/layout/AppHeader.tsx
@@ -76,6 +76,18 @@ export const AppHeader: React.FC<AppHeaderProps> = ({ autoSave }) => {
     setMenuOpen(false);
   }, [location.pathname]);
 
+  // Tauri desktop: skip the header entirely. The marketing nav was
+  // already hidden, but the strip itself was still painting an empty
+  // black bar over the editor. Brand/auto-save/share/auth-slot all
+  // live elsewhere in desktop: title bar shows "Velxio Desktop", the
+  // native menubar has File/Edit/View/Help, auto-save is a Pro cloud
+  // feature (desktop saves to .vlx), share generates a velxio.dev URL
+  // that doesn't apply to a desktop session, and the license flow
+  // owns its own DesktopWelcomePage.
+  if (import.meta.env.VITE_DESKTOP) {
+    return null;
+  }
+
   const isActive = (path: string) =>
     location.pathname === localize(path) ? ' header-nav-link-active' : '';
 
diff --git a/frontend/src/desktop/menu.ts b/frontend/src/desktop/menu.ts
index 3586737e..e760f163 100644
--- a/frontend/src/desktop/menu.ts
+++ b/frontend/src/desktop/menu.ts
@@ -26,6 +26,8 @@ import { listen } from './tauriBridge';
 import { dlog } from './log';
 import { triggerDownloadVlx, importVlxFile } from '../utils/vlxFile';
 import { useSimulatorStore } from '../store/useSimulatorStore';
+import { switchLocale } from '../i18n/path';
+import { LOCALES, type Locale } from '../i18n/config';
 
 type MenuAction =
   | 'new-project'
@@ -34,10 +36,14 @@ type MenuAction =
   | 'find-in-editor'
   | 'toggle-file-explorer'
   | 'toggle-serial-monitor'
-  | 'check-for-updates';
+  | 'check-for-updates'
+  | 'set-locale';
 
 interface MenuEventPayload {
   action: MenuAction;
+  // Only present when action='set-locale'. Matches an entry in
+  // i18n/config.ts::LOCALES.
+  locale?: string;
 }
 
 let installed = false;
@@ -47,11 +53,11 @@ export async function installDesktopMenuListener(): Promise<void> {
   installed = true;
   await listen<MenuEventPayload>('velxio://menu', (event) => {
     dlog('menu event', event.payload);
-    void handle(event.payload.action);
+    void handle(event.payload.action, event.payload);
   });
 }
 
-async function handle(action: MenuAction): Promise<void> {
+async function handle(action: MenuAction, payload?: MenuEventPayload): Promise<void> {
   switch (action) {
     case 'save-vlx':
       triggerDownloadVlx();
@@ -70,9 +76,34 @@ async function handle(action: MenuAction): Promise<void> {
     case 'check-for-updates':
       await checkForUpdates();
       return;
+    case 'set-locale':
+      if (payload?.locale) setLocale(payload.locale);
+      return;
   }
 }
 
+function setLocale(locale: string): void {
+  // Defensive: ignore unknown locales coming from the menu so a
+  // stale shell doesn't navigate to a broken URL.
+  if (!(LOCALES as readonly string[]).includes(locale)) {
+    dlog('set-locale: ignoring unknown locale', { locale });
+    return;
+  }
+  const target = locale as Locale;
+  const next =
+    switchLocale(window.location.pathname, target) +
+    window.location.search +
+    window.location.hash;
+  if (next === window.location.pathname + window.location.search + window.location.hash) {
+    return;
+  }
+  // history.pushState + popstate lets React Router pick the change up
+  // without a full reload, preserving the editor state. Reload would
+  // re-spawn the sidecar handshake and lose Monaco/sim state for ~5s.
+  window.history.pushState(null, '', next);
+  window.dispatchEvent(new PopStateEvent('popstate'));
+}
+
 function pickAndImportVlx(): void {
   const input = document.createElement('input');
   input.type = 'file';
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index 48fcb845..743e82ce 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -25,6 +25,23 @@ loader.config({ paths: { vs: monacoVsPath } });
 
 createRoot(document.getElementById('root')!).render(<App />);
 
+// Tear down the Tauri-only splash now that React has mounted. Wait
+// two animation frames so React's first paint commits before we
+// touch the splash — otherwise users see a black flash between the
+// splash fading and the editor first appearing. Fade via CSS
+// transition for a smoother handoff, then remove the node entirely
+// once the transition finishes.
+requestAnimationFrame(() => {
+  requestAnimationFrame(() => {
+    const splash = document.getElementById('velxio-splash');
+    if (!splash) return;
+    splash.style.transition = 'opacity 250ms ease-out';
+    splash.style.opacity = '0';
+    splash.style.pointerEvents = 'none';
+    window.setTimeout(() => splash.remove(), 320);
+  });
+});
+
 // Optional pro overlay. The `@pro` import resolves to a no-op stub in the
 // open-source build (see vite.config.ts) and to the real overlay only when
 // VITE_PRO_BUILD=true at build time. The dynamic import keeps the pro chunk
