README.md

@@ -102,6 +102,9 @@ dist/
   false outage)
 - Clickable service URLs
 - Canvas-based sparkline rendering with devicePixelRatio scaling
+- Mobile detection: viewports narrower than 768px show a friendly "not yet
+  available on mobile" message instead of the monitoring UI (no polling or
+  network requests on mobile)
 - Zero runtime dependencies: all resources bundled into build artifacts
 
 ## Deployment
@@ -125,6 +128,8 @@ properties.
 
 ## Limitations
 
+- **Mobile**: Viewports below 768px wide show a static "not yet available"
+  message. The full monitoring UI requires a desktop-width browser.
 - **CORS**: Some hosts may block cross-origin HEAD requests. The app uses
   `no-cors` mode which allows the request but provides opaque responses. Latency
   is still measurable based on request timing.

src/main.js

@@ -1126,11 +1126,46 @@ function handleResize(state) {
     });
 }
 
+// --- Mobile Detection --------------------------------------------------------
+
+const MOBILE_BREAKPOINT = 768;
+
+function isMobileViewport() {
+    return window.innerWidth < MOBILE_BREAKPOINT;
+}
+
+function buildMobileUI() {
+    const app = document.getElementById("app");
+    app.innerHTML = `
+    <div class="mx-auto px-[5%] py-8">
+      <header class="mb-8">
+        <h1 class="text-3xl font-bold text-white"><a href="https://git.eeqj.de/sneak/netwatch" target="_blank" rel="noopener" class="underline decoration-dashed decoration-gray-500 underline-offset-4">NetWatch</a> by <a href="https://sneak.berlin" target="_blank" rel="noopener" class="text-blue-400 underline hover:text-blue-300">@sneak</a></h1>
+        <p class="text-gray-400 text-sm mt-2">Real-time network latency monitor</p>
+      </header>
+      <div class="flex items-center justify-center min-h-[60vh]">
+        <div class="bg-gray-800/70 border border-gray-700/50 rounded-lg p-8 max-w-md text-center">
+          <p class="text-4xl mb-4">📡</p>
+          <p class="text-xl font-semibold text-white mb-2">Not yet available on mobile</p>
+          <p class="text-gray-400 text-sm">NetWatch requires a wider viewport to display latency charts and monitoring data. Please visit on a desktop browser.</p>
+        </div>
+      </div>
+      <footer class="mt-8 text-center text-gray-600 text-xs">
+        <p><a href="https://git.eeqj.de/sneak/netwatch/commit/${__COMMIT_FULL__}" target="_blank" rel="noopener" class="text-gray-600 hover:text-gray-400">${__COMMIT_HASH__}</a></p>
+      </footer>
+    </div>`;
+}
+
 // --- Bootstrap ---------------------------------------------------------------
 
 async function init() {
     log.info("NetWatch starting");
 
+    if (isMobileViewport()) {
+        log.info("Mobile viewport detected — skipping monitoring");
+        buildMobileUI();
+        return;
+    }
+
     // Probe common gateway IPs to find the local router
     const gateway = await detectGateway();
     const localHosts = [LOCAL_CPE];