diff --git a/cmd/mavweb/static/index.html b/cmd/mavweb/static/index.html
index 1ba1fd1..4cecdae 100644
--- a/cmd/mavweb/static/index.html
+++ b/cmd/mavweb/static/index.html
@@ -15,6 +15,8 @@ nav{display:flex;background:#1a1a2e;border-bottom:1px solid #333;flex-shrink:0}
 nav button{flex:1;padding:.6rem;background:none;border:none;color:#666;font-size:.85rem;cursor:pointer;font-family:inherit;letter-spacing:.05em;text-transform:uppercase;transition:color .15s;-webkit-tap-highlight-color:transparent}
 nav button.active{color:#00aaff;border-bottom:2px solid #00aaff}
 nav button:hover{color:#ddd}
+nav .lang{flex:0 0 auto;padding:.6rem .8rem;font-size:.75rem;color:#555;cursor:pointer;letter-spacing:.1em}
+nav .lang.active{color:#00aaff}
 
 .tab{display:none;flex-direction:column;align-items:center;flex:1;overflow:auto;padding:1rem}
 .tab.active{display:flex}
@@ -33,19 +35,24 @@ h1{font-size:1.2rem;font-weight:400;color:#888;letter-spacing:.1em;text-transfor
 
 #dash-frame{width:100%;flex:1;border:none;background:#111;min-height:0}
 
-/* cheatsheet — temporary reference while testing command lines */
 #cheat{width:100%;max-width:480px;font-size:.8rem;border-top:1px solid #222;color:#888}
 #cheat summary{cursor:pointer;padding:.5rem 0;color:#00aaff;letter-spacing:.05em;text-transform:uppercase;font-size:.75rem;user-select:none}
 #cheat dl{display:grid;grid-template-columns:auto 1fr;gap:.35rem .8rem;padding:.25rem 0 .5rem}
 #cheat dt{color:#00ff88;font-weight:600;white-space:nowrap}
 #cheat dd{color:#aaa;line-height:1.5}
 #cheat dd span{color:#555}
+.cheat-en{display:revert}
+.cheat-ru{display:none}
+html[data-lang=ru] .cheat-en { display: none; }
+html[data-lang=ru] .cheat-ru { display: revert; }
 </style>
 </head>
 <body>
 <nav>
   <button class="active" data-tab="voice">Voice</button>
   <button data-tab="dash">Dash</button>
+  <span class="lang active" data-lang="ru">RU</span>
+  <span class="lang" data-lang="en">EN</span>
 </nav>
 <div id="tab-voice" class="tab active">
   <h1>Maven Voice</h1>
@@ -53,14 +60,26 @@ h1{font-size:1.2rem;font-weight:400;color:#888;letter-spacing:.1em;text-transfor
   <button id="btn" type="button">&#x1f399;</button>
   <div id="log"></div>
   <details id="cheat">
-    <summary>Cheatsheet · шпаргалка</summary>
+    <summary>Cheatsheet</summary>
     <dl>
-      <dt>Act</dt><dd>включи свет · сделай громче · <span>restart nginx</span></dd>
-      <dt>Reminder</dt><dd>напомни через 4 часа размяться · <span>remind me tomorrow at 8am to call the doctor</span></dd>
-      <dt>Fact</dt><dd>выпил кофе · вес 73 кг · <span>ran 3 kilometers</span></dd>
-      <dt>Note</dt><dd>запиши рецепт блинов · <span>note: add a backup job for the db</span></dd>
-      <dt>Query</dt><dd>какой сегодня день · какой прогноз погоды · <span>what version are you</span></dd>
-      <dt>System</dt><dd>включи тихий режим · как загрузка системы</dd>
+      <dt>Act</dt>
+      <dd class="cheat-ru">включи свет · сделай громче</dd>
+      <dd class="cheat-en">restart nginx · turn on the light</dd>
+      <dt>Reminder</dt>
+      <dd class="cheat-ru">напомни через 4 часа размяться</dd>
+      <dd class="cheat-en">remind me tomorrow at 8am to call the doctor</dd>
+      <dt>Fact</dt>
+      <dd class="cheat-ru">выпил кофе · вес 73 кг</dd>
+      <dd class="cheat-en">ran 3 kilometers</dd>
+      <dt>Note</dt>
+      <dd class="cheat-ru">запиши рецепт блинов</dd>
+      <dd class="cheat-en">note: add a backup job for the db</dd>
+      <dt>Query</dt>
+      <dd class="cheat-ru">какой сегодня день · какой прогноз погоды</dd>
+      <dd class="cheat-en">what version are you · what's the weather</dd>
+      <dt>System</dt>
+      <dd class="cheat-ru">включи тихий режим · как загрузка системы</dd>
+      <dd class="cheat-en">quiet mode on · system load</dd>
     </dl>
   </details>
 </div>
@@ -68,15 +87,37 @@ h1{font-size:1.2rem;font-weight:400;color:#888;letter-spacing:.1em;text-transfor
   <iframe id="dash-frame" src="/dash"></iframe>
 </div>
 <script>
-document.querySelectorAll('nav button').forEach(function(btn) {
-  btn.addEventListener('click', function() {
-    document.querySelectorAll('nav button').forEach(function(b) { b.classList.remove('active'); });
-    document.querySelectorAll('.tab').forEach(function(t) { t.classList.remove('active'); });
-    btn.classList.add('active');
-    var tab = document.getElementById('tab-' + btn.dataset.tab);
-    if (tab) tab.classList.add('active');
+(function() {
+  // Read lang from URL param or default to ru
+  var lang = new URLSearchParams(window.location.search).get('lang') || 'ru';
+  if (lang !== 'en') lang = 'ru';
+  document.documentElement.setAttribute('data-lang', lang);
+
+  // Nav buttons
+  document.querySelectorAll('nav button[data-tab]').forEach(function(btn) {
+    btn.addEventListener('click', function() {
+      document.querySelectorAll('nav button[data-tab]').forEach(function(b) { b.classList.remove('active'); });
+      document.querySelectorAll('.tab').forEach(function(t) { t.classList.remove('active'); });
+      btn.classList.add('active');
+      var tab = document.getElementById('tab-' + btn.dataset.tab);
+      if (tab) tab.classList.add('active');
+    });
   });
-});
+
+  // Lang toggle
+  document.querySelectorAll('nav .lang').forEach(function(el) {
+    el.addEventListener('click', function() {
+      var l = el.dataset.lang;
+      document.documentElement.setAttribute('data-lang', l);
+      document.querySelectorAll('nav .lang').forEach(function(b) { b.classList.remove('active'); });
+      el.classList.add('active');
+      // Update URL without reload
+      var url = new URL(window.location);
+      url.searchParams.set('lang', l);
+      history.replaceState(null, '', url);
+    });
+  });
+})();
 </script>
 </body>
 </html>
