diff --git a/frontend/src/components/App.tsx b/frontend/src/components/App.tsx
index 9d7cde8..8ff3917 100644
--- a/frontend/src/components/App.tsx
+++ b/frontend/src/components/App.tsx
@@ -9,9 +9,9 @@ import { ResultsSkeleton } from './ResultsSkeleton';
 import { ToolPanels } from './tools/ToolPanels';
 import { ScanComparison } from './views/ScanComparison';
 import { WatchlistView } from './views/WatchlistView';
-import { MODULE_MAP } from './Sidebar';
 import { startScan, getWsUrl, getScan, getUsage } from '@/lib/api';
 import { detectScanType, normalizeScanTarget } from '@/lib/scan-target';
+import { MODULE_MAP } from './Sidebar';
 import type { ScanType, ScanStatus, ToolMode, ScanResults as ScanResultsType, ScanMeta, LiveModuleStatus, UsageData } from '@/lib/types';
 
 type View = 'idle' | 'tool' | 'scanning' | 'results' | 'compare' | 'watchlist';
@@ -47,7 +47,9 @@ export function App() {
   const [totalModules, setTotalModules] = useState(0);
   const [compareIds, setCompareIds] = useState<[string, string] | null>(null);
   const [usage, setUsage] = useState<UsageData | null>(null);
+  const [isStarting, setIsStarting] = useState(false);
   const wsRef = useRef<WebSocket | null>(null);
+  const urlScanStarted = useRef(false);
   const usageLimitedRef = useRef(true);
 
   const handleHome = useCallback(() => {
@@ -228,29 +230,23 @@ export function App() {
     setProgressLog([]);
     setModuleStatuses({});
     setTotalModules(modules.length);
-    setScanStatus('running');
-    setView('scanning');
     setScanMeta(null);
+    setIsStarting(true);
     try {
       const { scan_id } = await startScan(target, type, modules);
+      setIsStarting(false);
+      setScanStatus('running');
+      setView('scanning');
       setScanId(scan_id);
       connectWs(scan_id);
       handleUsageRefresh();
     } catch (e: unknown) {
+      setIsStarting(false);
       setScanStatus('failed');
       setProgressLog([`Failed to start scan: ${e instanceof Error ? e.message : 'Unknown error'}`]);
     }
   }, [connectWs, handleUsageRefresh]);
 
-  useEffect(() => {
-    handleUsageRefresh();
-  }, [handleUsageRefresh]);
-
-  useEffect(() => {
-    return () => { wsRef.current?.close(); };
-  }, []);
-
-  const urlScanStarted = useRef(false);
   useEffect(() => {
     if (urlScanStarted.current) return;
     try {
@@ -265,14 +261,22 @@ export function App() {
     } catch {}
   }, [handleScan]);
 
+  useEffect(() => {
+    handleUsageRefresh();
+  }, [handleUsageRefresh]);
+
+  useEffect(() => {
+    return () => { wsRef.current?.close(); };
+  }, []);
+
   return (
     <div className="flex flex-col min-h-screen">
       <Topbar status={scanStatus} usage={usage} onHome={handleHome} onWatchlist={handleWatchlist} onMenuToggle={() => setSidebarOpen(v => !v)} />
       <div className="flex flex-1 relative">
         {sidebarOpen && <div onClick={() => setSidebarOpen(false)} className="fixed inset-0 bg-black/50 z-40 md:hidden" />}
-        <Sidebar onScan={handleScan} onLoadScan={handleLoadScan} onCompare={handleCompare} isRunning={scanStatus === 'running'} isOpen={sidebarOpen} onClose={() => setSidebarOpen(false)} />
+        <Sidebar onScan={handleScan} onLoadScan={handleLoadScan} onCompare={handleCompare} isRunning={scanStatus === 'running'} isStarting={isStarting} isOpen={sidebarOpen} onClose={() => setSidebarOpen(false)} />
         <main className="flex-1 min-w-0 relative z-10">
-          {view === 'idle' && <IdleView onTool={handleTool} onScan={handleScan} />}
+          {view === 'idle' && <IdleView onTool={handleTool} onScan={handleScan} isStarting={isStarting} />}
           {view === 'tool' && toolMode && (
             <ToolPanels mode={toolMode} onBack={() => setView('idle')} />
           )}
@@ -293,4 +297,4 @@ export function App() {
       </div>
     </div>
   );
-}
+}
\ No newline at end of file
diff --git a/frontend/src/components/Sidebar.tsx b/frontend/src/components/Sidebar.tsx
index b131b2b..8396193 100644
--- a/frontend/src/components/Sidebar.tsx
+++ b/frontend/src/components/Sidebar.tsx
@@ -30,6 +30,7 @@ interface Props {
   onLoadScan?: (scanId: string) => void;
   onCompare?: (a: string, b: string) => void;
   isRunning: boolean;
+  isStarting?: boolean;
   isOpen: boolean;
   onClose: () => void;
 }
@@ -55,7 +56,7 @@ function useRecentScans() {
   return { recents, add, clear };
 }
 
-export function Sidebar({ onScan, onLoadScan, onCompare, isRunning, isOpen, onClose }: Props) {
+export function Sidebar({ onScan, onLoadScan, onCompare, isRunning, isStarting = false, isOpen, onClose }: Props) {
   const { t } = useTranslations();
   const [target, setTarget] = useState('');
   const [scanType, setScanType] = useState<ScanType>('domain');
@@ -211,11 +212,11 @@ export function Sidebar({ onScan, onLoadScan, onCompare, isRunning, isOpen, onCl
 
         <button
           type="submit"
-          disabled={!target.trim() || isRunning || modules.length === 0}
+          disabled={!target.trim() || isRunning || isStarting || modules.length === 0}
           className="btn-primary mt-1"
         >
-          {isRunning ? <Loader2 size={13} className="spin" /> : <Play size={13} />}
-          {isRunning ? t('sidebar.scanning') : t('sidebar.runScan')}
+          {(isRunning || isStarting) ? <Loader2 size={13} className="spin" /> : <Play size={13} />}
+          {isRunning ? t('sidebar.scanning') : isStarting ? t('sidebar.scanning') : t('sidebar.runScan')}
         </button>
       </form>
 
@@ -367,4 +368,4 @@ export function Sidebar({ onScan, onLoadScan, onCompare, isRunning, isOpen, onCl
       </div>
     </aside>
   );
-}
+}
\ No newline at end of file
diff --git a/frontend/src/components/views/IdleView.tsx b/frontend/src/components/views/IdleView.tsx
index 0ba5399..452ff8d 100644
--- a/frontend/src/components/views/IdleView.tsx
+++ b/frontend/src/components/views/IdleView.tsx
@@ -1,6 +1,6 @@
 'use client';
 import { useEffect, useState } from 'react';
-import { FileText, Mail, Bitcoin, QrCode, ChevronRight, Globe, User, Phone, Shield, Database, Zap, Eye, Activity, Network, Hash, Binary, KeyRound, Search } from 'lucide-react';
+import { FileText, Mail, Bitcoin, QrCode, ChevronRight, Globe, User, Phone, Shield, Database, Zap, Eye, Activity, Network, Hash, Binary, KeyRound, Search, Loader2 } from 'lucide-react';
 import { useTranslations } from '@/lib/i18n';
 import { getPrismDemoMode } from '@/lib/prism-config';
 import { detectScanType, normalizeScanTarget } from '@/lib/scan-target';
@@ -29,9 +29,10 @@ type CapsKey = typeof CAPS_KEYS[number];
 interface Props {
   onTool: (mode: ToolMode) => void;
   onScan: (target: string, type: ScanType, modules: string[]) => void;
+  isStarting?: boolean;
 }
 
-export function IdleView({ onTool, onScan }: Props) {
+export function IdleView({ onTool, onScan, isStarting = false }: Props) {
   const { t } = useTranslations();
   const demoMode = getPrismDemoMode();
   const [targetIdx, setTargetIdx] = useState(0);
@@ -110,11 +111,11 @@ export function IdleView({ onTool, onScan }: Props) {
         </div>
         <button
           type="submit"
-          disabled={!query.trim()}
+          disabled={!query.trim() || isStarting}
           className="btn-primary h-[42px] px-4 shrink-0 disabled:opacity-50 disabled:cursor-not-allowed"
           aria-label={t('sidebar.runScan')}
         >
-          <Search size={15} />
+          {isStarting ? <Loader2 size={15} className="spin" /> : <Search size={15} />}
         </button>
       </form>
 
@@ -194,4 +195,4 @@ export function IdleView({ onTool, onScan }: Props) {
       )}
     </div>
   );
-}
+}
\ No newline at end of file