frontend/src/app/admin/scanner/page.tsx

@@ -9,6 +9,7 @@ import {
   QrCodeIcon,
   CheckCircleIcon,
   XCircleIcon,
+  XMarkIcon,
   MagnifyingGlassIcon,
   ArrowPathIcon,
   ClockIcon,
@@ -76,86 +77,135 @@ function vibrate(pattern: number | number[]) {
   } catch {}
 }
 
+// ─── Stop all tracks on a media stream ───────────────────────
+function stopAllTracks() {
+  try {
+    // Find all video elements and stop their streams
+    document.querySelectorAll('video').forEach((video) => {
+      const stream = video.srcObject as MediaStream | null;
+      if (stream) {
+        stream.getTracks().forEach((track) => track.stop());
+        video.srcObject = null;
+      }
+    });
+  } catch {}
+}
+
 // ─── QR Scanner Component ────────────────────────────────────
+// This component fully mounts/unmounts — use a key prop externally
+// to force a fresh instance when the scan tab becomes active.
 function QRScanner({
   onScan,
-  isActive,
+  onError,
-  onActiveChange,
 }: {
   onScan: (code: string) => void;
-  isActive: boolean;
+  onError: () => void;
-  onActiveChange: (active: boolean) => void;
 }) {
   const containerRef = useRef<HTMLDivElement>(null);
   const scannerRef = useRef<any>(null);
-  const scannerElementId = useRef(`qr-scanner-${Math.random().toString(36).substr(2, 9)}`);
+  const mountedRef = useRef(true);
+  const elementId = useRef(`qr-scanner-${Date.now()}`);
   const [facingMode, setFacingMode] = useState<'environment' | 'user'>('environment');
+  const [ready, setReady] = useState(false);
 
-  useEffect(() => {
+  // Full cleanup helper
-    if (containerRef.current && !document.getElementById(scannerElementId.current)) {
+  const destroyScanner = useCallback(async () => {
-      const scannerDiv = document.createElement('div');
+    if (scannerRef.current) {
-      scannerDiv.id = scannerElementId.current;
+      try { await scannerRef.current.stop(); } catch {}
-      scannerDiv.style.width = '100%';
+      try { scannerRef.current.clear(); } catch {}
-      containerRef.current.appendChild(scannerDiv);
+      scannerRef.current = null;
     }
-    return () => {
+    stopAllTracks();
-      if (scannerRef.current) {
-        try { scannerRef.current.stop().catch(() => {}); } catch {}
-        scannerRef.current = null;
-      }
-    };
   }, []);
 
+  // Start scanner on mount, destroy on unmount
   useEffect(() => {
+    mountedRef.current = true;
     let cancelled = false;
 
-    const startScanner = async () => {
+    const init = async () => {
-      const elementId = scannerElementId.current;
+      const container = containerRef.current;
-      const element = document.getElementById(elementId);
+      if (!container) return;
-      if (!element) return;
+
+      // Create a fresh div for the scanner
+      const id = elementId.current;
+      container.innerHTML = '';
+      const div = document.createElement('div');
+      div.id = id;
+      div.style.width = '100%';
+      div.style.height = '100%';
+      container.appendChild(div);
 
       try {
         const { Html5Qrcode } = await import('html5-qrcode');
         if (cancelled) return;
-        if (scannerRef.current) {
-          try { await scannerRef.current.stop(); } catch {}
-          scannerRef.current = null;
-        }
-        if (cancelled) return;
 
-        const scanner = new Html5Qrcode(elementId);
+        const scanner = new Html5Qrcode(id);
         scannerRef.current = scanner;
 
         await scanner.start(
           { facingMode },
           { fps: 10, qrbox: { width: 250, height: 250 }, aspectRatio: 1 },
-          (decodedText: string) => onScan(decodedText),
+          (decodedText: string) => {
+            if (mountedRef.current) onScan(decodedText);
+          },
           () => {}
         );
+
+        if (cancelled) {
+          await destroyScanner();
+          return;
+        }
+
+        // Force layout recalculation after camera starts
+        requestAnimationFrame(() => {
+          if (container) {
+            container.style.display = 'none';
+            // eslint-disable-next-line @typescript-eslint/no-unused-expressions
+            container.offsetHeight; // force reflow
+            container.style.display = '';
+          }
+          if (mountedRef.current) setReady(true);
+        });
       } catch (error: any) {
         console.error('Scanner error:', error);
-        if (!cancelled) {
+        if (!cancelled && mountedRef.current) {
           toast.error('Failed to start camera. Check permissions.');
-          onActiveChange(false);
+          onError();
         }
       }
     };
 
-    const stopScanner = async () => {
+    init();
-      if (scannerRef.current) {
+
-        try { await scannerRef.current.stop(); } catch {}
+    return () => {
-        scannerRef.current = null;
+      cancelled = true;
+      mountedRef.current = false;
+      destroyScanner();
+    };
+  }, [facingMode]); // restart when camera flips
+
+  // Handle browser visibility change (suspend/resume)
+  useEffect(() => {
+    const handleVisibility = () => {
+      if (document.visibilityState === 'hidden') {
+        destroyScanner();
+      } else if (document.visibilityState === 'visible' && mountedRef.current) {
+        // Re-trigger by flipping facingMode back-and-forth (forces useEffect re-run)
+        setFacingMode((prev) => {
+          // Toggle and toggle back to trigger the effect
+          const temp = prev === 'environment' ? 'user' : 'environment';
+          setTimeout(() => {
+            if (mountedRef.current) setFacingMode(prev);
+          }, 100);
+          return temp;
+        });
       }
     };
 
-    if (isActive) {
+    document.addEventListener('visibilitychange', handleVisibility);
-      startScanner();
+    return () => document.removeEventListener('visibilitychange', handleVisibility);
-    } else {
+  }, [destroyScanner]);
-      stopScanner();
-    }
-
-    return () => { cancelled = true; };
-  }, [isActive, facingMode, onScan, onActiveChange]);
 
   const switchCamera = () => {
     setFacingMode((prev) => (prev === 'environment' ? 'user' : 'environment'));
@@ -163,8 +213,11 @@ function QRScanner({
 
   return (
     <div className="relative w-full bg-black flex-1 min-h-0 overflow-hidden">
-      <div ref={containerRef} className="w-full h-full [&_video]:!object-cover [&_video]:!h-full" />
+      <div
-      {isActive && (
+        ref={containerRef}
+        className="w-full h-full [&_video]:!object-cover [&_video]:!h-full [&_video]:!w-full"
+      />
+      {ready && (
         <button
           onClick={switchCamera}
           className="absolute top-3 right-3 z-10 bg-black/50 backdrop-blur-sm text-white p-2.5 rounded-full active:scale-95 transition-transform"
@@ -173,7 +226,7 @@ function QRScanner({
           <VideoCameraIcon className="w-5 h-5" />
         </button>
       )}
-      {!isActive && (
+      {!ready && (
         <div className="absolute inset-0 flex items-center justify-center text-gray-400">
           <div className="text-center">
             <QrCodeIcon className="w-16 h-16 mx-auto mb-2 opacity-30" />
@@ -189,15 +242,27 @@ function QRScanner({
 function ValidTicketScreen({
   validation,
   onConfirmCheckin,
+  onClose,
   checkingIn,
 }: {
   validation: TicketValidationResult;
   onConfirmCheckin: () => void;
+  onClose: () => void;
   checkingIn: boolean;
 }) {
   return (
     <div className="fixed inset-0 z-50 bg-emerald-600 flex flex-col animate-in fade-in duration-200">
-      <div className="flex-1 flex flex-col items-center justify-center px-6 text-white">
+      {/* Close button (dismiss without check-in) */}
+      <div className="flex justify-end p-4">
+        <button
+          onClick={onClose}
+          className="p-2 rounded-full bg-white/20 text-white active:scale-95 transition-transform"
+          aria-label="Close"
+        >
+          <XMarkIcon className="w-6 h-6" />
+        </button>
+      </div>
+      <div className="flex-1 flex flex-col items-center justify-center px-6 -mt-14 text-white">
         <div className="w-24 h-24 rounded-full bg-white/20 flex items-center justify-center mb-6">
           <CheckCircleIcon className="w-16 h-16 text-white" />
         </div>
@@ -581,7 +646,7 @@ export default function AdminScannerPage() {
   const [activeTab, setActiveTab] = useState<ActiveTab>('scan');
 
   // Scanner state
-  const [cameraActive, setCameraActive] = useState(false);
+  const [scannerKey, setScannerKey] = useState(0); // increment to force remount
   const [scanResult, setScanResult] = useState<ScanResultData>({ state: 'idle' });
   const [lastScannedCode, setLastScannedCode] = useState('');
   const [checkingIn, setCheckingIn] = useState(false);
@@ -638,21 +703,8 @@ export default function AdminScannerPage() {
     loadStats();
   }, [selectedEventId]);
 
-  // Auto-start camera on page load (Scan tab)
+  // When scan tab becomes active again or scan result is dismissed, bump key to remount scanner
-  useEffect(() => {
+  const scannerActive = activeTab === 'scan' && scanResult.state === 'idle' && !loading;
-    if (!loading && activeTab === 'scan') {
-      setCameraActive(true);
-    }
-  }, [loading, activeTab]);
-
-  // Pause camera when switching away from scan tab
-  useEffect(() => {
-    if (activeTab !== 'scan') {
-      setCameraActive(false);
-    } else if (scanResult.state === 'idle') {
-      setCameraActive(true);
-    }
-  }, [activeTab, scanResult.state]);
 
   // Validate ticket
   const validateTicket = useCallback(async (code: string) => {
@@ -690,7 +742,6 @@ export default function AdminScannerPage() {
     if (decodedText === lastScannedCodeRef.current) return;
     lastScannedCodeRef.current = decodedText;
     setLastScannedCode(decodedText);
-    setCameraActive(false);
 
     let code = decodedText;
     const urlMatch = decodedText.match(/\/ticket\/([a-zA-Z0-9-_]+)/);
@@ -768,12 +819,12 @@ export default function AdminScannerPage() {
     }
   };
 
-  // Reset scan state
+  // Reset scan state — bump key so scanner fully remounts
   const resetScan = () => {
     setScanResult({ state: 'idle' });
     setLastScannedCode('');
     lastScannedCodeRef.current = '';
-    if (activeTab === 'scan') setCameraActive(true);
+    setScannerKey((k) => k + 1);
   };
 
   // Get selected event name
@@ -788,7 +839,7 @@ export default function AdminScannerPage() {
   }
 
   return (
-    <div className="min-h-screen bg-gray-950 flex flex-col h-screen max-h-screen overflow-hidden">
+    <div className="bg-gray-950 flex flex-col overflow-hidden" style={{ height: '100dvh' }}>
       {/* ── Sticky Header ── */}
       <header className="flex-shrink-0 bg-gray-900 border-b border-gray-800 px-4 py-3 safe-area-top">
         <div className="flex items-center justify-between gap-3">
@@ -864,14 +915,17 @@ export default function AdminScannerPage() {
 
       {/* ── Tab Content ── */}
       <div className="flex-1 min-h-0 flex flex-col overflow-hidden">
-        {/* SCAN TAB */}
+        {/* SCAN TAB — scanner fully unmounts when not active */}
-        {activeTab === 'scan' && (
+        {scannerActive && (
           <QRScanner
-            isActive={cameraActive && scanResult.state === 'idle'}
+            key={scannerKey}
             onScan={handleScan}
-            onActiveChange={setCameraActive}
+            onError={() => {}}
           />
         )}
+        {activeTab === 'scan' && !scannerActive && scanResult.state !== 'idle' && (
+          <div className="flex-1 bg-black" />
+        )}
 
         {/* SEARCH TAB */}
         {activeTab === 'search' && (
@@ -889,6 +943,7 @@ export default function AdminScannerPage() {
         <ValidTicketScreen
           validation={scanResult.validation}
           onConfirmCheckin={handleCheckin}
+          onClose={resetScan}
           checkingIn={checkingIn}
         />
       )}