diff --git a/webui/index.html b/webui/index.html
index d642c8d98..070e9966d 100644
--- a/webui/index.html
+++ b/webui/index.html
@@ -14,6 +14,7 @@
     <link rel="icon" type="image/svg+xml" href="/brand/nanobot_mark.svg" />
     <link rel="alternate icon" type="image/png" sizes="32x32" href="/brand/nanobot_favicon_32.png" />
     <link rel="apple-touch-icon" sizes="180x180" href="/brand/nanobot_apple_touch.png" />
+    <link rel="manifest" href="/manifest.json" />
     <style>
       html,
       body,
diff --git a/webui/public/brand/nanobot_icon_192.png b/webui/public/brand/nanobot_icon_192.png
new file mode 100644
index 000000000..0559e9133
Binary files /dev/null and b/webui/public/brand/nanobot_icon_192.png differ
diff --git a/webui/public/brand/nanobot_icon_512.png b/webui/public/brand/nanobot_icon_512.png
new file mode 100644
index 000000000..3b11e435c
Binary files /dev/null and b/webui/public/brand/nanobot_icon_512.png differ
diff --git a/webui/public/brand/nanobot_icon_maskable.png b/webui/public/brand/nanobot_icon_maskable.png
new file mode 100644
index 000000000..3bcea79d3
Binary files /dev/null and b/webui/public/brand/nanobot_icon_maskable.png differ
diff --git a/webui/public/manifest.json b/webui/public/manifest.json
new file mode 100644
index 000000000..aedf679af
--- /dev/null
+++ b/webui/public/manifest.json
@@ -0,0 +1,33 @@
+{
+  "name": "nanobot",
+  "short_name": "nanobot",
+  "description": "nanobot AI assistant",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#161618",
+  "theme_color": "#161618",
+  "orientation": "any",
+  "icons": [
+    {
+      "src": "/brand/nanobot_apple_touch.png",
+      "sizes": "180x180",
+      "type": "image/png"
+    },
+    {
+      "src": "/brand/nanobot_icon_192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/brand/nanobot_icon_512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    },
+    {
+      "src": "/brand/nanobot_icon_maskable.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
+  ]
+}
diff --git a/webui/public/sw.js b/webui/public/sw.js
new file mode 100644
index 000000000..4ebaa63b4
--- /dev/null
+++ b/webui/public/sw.js
@@ -0,0 +1,72 @@
+const CACHE_NAME = "nanobot-static-v1";
+const PRECACHE = ["/", "/manifest.json"];
+
+self.addEventListener("install", (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME).then((cache) => cache.addAll(PRECACHE))
+  );
+  self.skipWaiting();
+});
+
+self.addEventListener("activate", (event) => {
+  event.waitUntil(
+    caches.keys().then((keys) =>
+      Promise.all(
+        keys
+          .filter((k) => k !== CACHE_NAME)
+          .map((k) => caches.delete(k))
+      )
+    )
+  );
+  self.clients.claim();
+});
+
+self.addEventListener("fetch", (event) => {
+  const { request } = event;
+
+  // Only handle same-origin GET requests
+  if (request.method !== "GET") return;
+  if (new URL(request.url).origin !== self.location.origin) return;
+
+  const url = new URL(request.url);
+  const path = url.pathname;
+
+  // Never cache API, auth, WebSocket, or HMR paths
+  if (
+    path.startsWith("/api") ||
+    path.startsWith("/auth") ||
+    path.startsWith("/__nanobot")
+  ) {
+    return;
+  }
+
+  // Static assets: cache-first (immutable by gateway)
+  if (/\.(js|css|png|webp|ico|svg|woff2?|ttf|eot)$/.test(path)) {
+    event.respondWith(
+      caches.match(request).then((cached) => {
+        if (cached) return cached;
+        return fetch(request).then((response) => {
+          if (response.ok) {
+            const clone = response.clone();
+            caches.open(CACHE_NAME).then((c) => c.put(request, clone));
+          }
+          return response;
+        });
+      })
+    );
+    return;
+  }
+
+  // Everything else: network-first (index.html, manifest, etc.)
+  event.respondWith(
+    fetch(request)
+      .then((response) => {
+        if (response.ok) {
+          const clone = response.clone();
+          caches.open(CACHE_NAME).then((c) => c.put(request, clone));
+        }
+        return response;
+      })
+      .catch(() => caches.match(request))
+  );
+});
diff --git a/webui/src/main.tsx b/webui/src/main.tsx
index 2fc96fd80..24fc02fbb 100644
--- a/webui/src/main.tsx
+++ b/webui/src/main.tsx
@@ -28,3 +28,11 @@ initializeLoopbackRuntimeHost();
 
 /* StrictMode disabled: dev double-invokes state updaters; delta accumulation must stay pure — see useNanobotStream. */
 ReactDOM.createRoot(root).render(<App />);
+
+if ("serviceWorker" in navigator) {
+  window.addEventListener("load", () => {
+    navigator.serviceWorker.register("/sw.js", {
+      updateViaCache: "none",
+    });
+  });
+}