tam 2

client/app.go

@@ -125,20 +125,25 @@ type App struct {
 	sessionPath       string
 	statsPath         string
 	webviewDataPath   string
+	pendingViolPath   string
+	runLockPath       string
 	wsConn            *websocket.Conn
-	wsConnected    bool
-	wifiSSID       string
-	wifiBSSID      string
-	allowedApps    string
-	onlineSecs     int
-	offlineSecs    int
-	unsyncedOn     int
-	unsyncedOff    int
-	lastSyncTime   time.Time
-	isStreamingSc  bool
-	streamScStop   chan struct{}
-	isStreamingCam bool
-	streamCamStop  chan struct{}
+	wsConnected       bool
+	wsConnecting      bool
+	wsBackoff         time.Duration
+	wsWriteMu         sync.Mutex
+	wifiSSID          string
+	wifiBSSID         string
+	allowedApps       string
+	onlineSecs        int
+	offlineSecs       int
+	unsyncedOn        int
+	unsyncedOff       int
+	lastSyncTime      time.Time
+	isStreamingSc     bool
+	streamScStop      chan struct{}
+	isStreamingCam    bool
+	streamCamStop     chan struct{}
 	statusMsg               string
 	expectingLogin          bool
 	needsClearPortalStorage bool
@@ -152,7 +157,6 @@ type App struct {
 	chatUnread        int
 	replyStaffID      uint
 	fetchAppsMu       sync.Mutex
-	wsWriteMu         sync.Mutex
 }
 
 type LocalStats struct {
@@ -213,11 +217,13 @@ func NewApp() *App {
 	_ = os.MkdirAll(webviewDir, 0755)
 
 	return &App{
-		sessionPath:     filepath.Join(appDir, "student_session.json"),
-		statsPath:       filepath.Join(appDir, "student_stats.json"),
-		webviewDataPath: webviewDir,
-		lastSyncTime:   time.Now(),
-		expectingLogin: false,
+		sessionPath:       filepath.Join(appDir, "student_session.json"),
+		statsPath:         filepath.Join(appDir, "student_stats.json"),
+		webviewDataPath:   webviewDir,
+		pendingViolPath:   filepath.Join(appDir, "pending_violations.json"),
+		runLockPath:       filepath.Join(appDir, "monitoring.lock"),
+		lastSyncTime:      time.Now(),
+		expectingLogin:    false,
 	}
 }
 
@@ -226,6 +232,10 @@ func (a *App) startup(ctx context.Context) {
 	a.loadSession()
 	a.loadStats()
 
+	// Task Manager / kill process lần trước → còn file lock → báo unclean_shutdown
+	a.detectUncleanShutdown()
+	go a.flushPendingViolations()
+
 	// Request Location Access (macOS)
 	winapi.RequestLocationAccess()
 	winapi.RequestCameraAndMicAccess()
@@ -268,10 +278,35 @@ func (a *App) startup(ctx context.Context) {
 	go a.authStorageScanner()
 }
 
-func (a *App) handleGuardViolation(reason string) {
+func (a *App) handleGuardViolation(kind, reason string) {
+	if kind == "" {
+		kind = "guard"
+	}
+	a.reportViolation(kind, reason)
 	a.showQuitDialog("Vi phạm giám sát", reason)
 }
 
+// HandleBeforeClose — SV bấm X / Alt+F4 khi đang giám sát = vi phạm.
+// Trả về false để cho phép đóng sau khi đã báo cáo.
+func (a *App) HandleBeforeClose() (prevent bool) {
+	if !a.CheckLoginStatus() || !a.isMonitoringActive() {
+		a.clearRunLock()
+		return false
+	}
+	a.mu.Lock()
+	mode := a.dashboard.MonitorMode
+	a.mu.Unlock()
+	if mode == "" || mode == "not_configured" {
+		a.clearRunLock()
+		return false
+	}
+
+	a.reportViolation("app_closed", "Sinh viên tự đóng ứng dụng khi đang giám sát ("+mode+")")
+	a.tearDownBeforeQuit()
+	a.clearRunLock()
+	return false
+}
+
 // tearDownBeforeQuit ngắt mọi kênh giám sát ngay — trước khi hiện dialog (tránh treo OK để duy trì kết nối).
 func (a *App) tearDownBeforeQuit() {
 	a.mu.Lock()
@@ -287,6 +322,7 @@ func (a *App) tearDownBeforeQuit() {
 	a.stopWebcamStream()
 	a.disconnectWS()
 	guard.Stop()
+	a.clearRunLock()
 }
 
 func (a *App) isMonitoringActive() bool {
@@ -315,6 +351,162 @@ func (a *App) showQuitDialog(title, message string) {
 	runtime.Quit(a.ctx)
 }
 
+type pendingViolation struct {
+	Kind        string `json:"kind"`
+	Reason      string `json:"reason"`
+	MonitorMode string `json:"monitorMode"`
+	ClientAt    string `json:"clientAt"`
+	StudentRkID int64  `json:"studentRkId"`
+}
+
+func (a *App) markRunLock() {
+	a.mu.Lock()
+	studentID := int64(0)
+	mode := a.dashboard.MonitorMode
+	if a.student != nil {
+		studentID = a.student.StudentID
+	}
+	a.mu.Unlock()
+	if studentID <= 0 || mode == "" || mode == "not_configured" {
+		return
+	}
+	payload, _ := json.Marshal(map[string]any{
+		"studentRkId": studentID,
+		"monitorMode": mode,
+		"startedAt":   time.Now().Format(time.RFC3339),
+	})
+	_ = os.WriteFile(a.runLockPath, payload, 0644)
+}
+
+func (a *App) clearRunLock() {
+	_ = os.Remove(a.runLockPath)
+}
+
+func (a *App) detectUncleanShutdown() {
+	data, err := os.ReadFile(a.runLockPath)
+	if err != nil {
+		return
+	}
+	_ = os.Remove(a.runLockPath)
+
+	var meta struct {
+		StudentRkID int64  `json:"studentRkId"`
+		MonitorMode string `json:"monitorMode"`
+		StartedAt   string `json:"startedAt"`
+	}
+	_ = json.Unmarshal(data, &meta)
+	if meta.StudentRkID <= 0 {
+		a.mu.Lock()
+		if a.student != nil {
+			meta.StudentRkID = a.student.StudentID
+		}
+		a.mu.Unlock()
+	}
+	if meta.StudentRkID <= 0 {
+		return
+	}
+	reason := "Ứng dụng bị tắt đột ngột (Task Manager / kill process) khi đang giám sát"
+	if meta.MonitorMode != "" {
+		reason += " (" + meta.MonitorMode + ")"
+	}
+	a.enqueuePendingViolation(pendingViolation{
+		Kind:        "unclean_shutdown",
+		Reason:      reason,
+		MonitorMode: meta.MonitorMode,
+		ClientAt:    time.Now().Format(time.RFC3339),
+		StudentRkID: meta.StudentRkID,
+	})
+}
+
+func (a *App) enqueuePendingViolation(v pendingViolation) {
+	list := a.loadPendingViolations()
+	list = append(list, v)
+	raw, _ := json.Marshal(list)
+	_ = os.WriteFile(a.pendingViolPath, raw, 0644)
+}
+
+func (a *App) loadPendingViolations() []pendingViolation {
+	data, err := os.ReadFile(a.pendingViolPath)
+	if err != nil {
+		return nil
+	}
+	var list []pendingViolation
+	if json.Unmarshal(data, &list) != nil {
+		return nil
+	}
+	return list
+}
+
+func (a *App) flushPendingViolations() {
+	list := a.loadPendingViolations()
+	if len(list) == 0 {
+		return
+	}
+	remaining := make([]pendingViolation, 0)
+	for _, v := range list {
+		if !a.postViolation(v) {
+			remaining = append(remaining, v)
+		}
+	}
+	if len(remaining) == 0 {
+		_ = os.Remove(a.pendingViolPath)
+		return
+	}
+	raw, _ := json.Marshal(remaining)
+	_ = os.WriteFile(a.pendingViolPath, raw, 0644)
+}
+
+func (a *App) postViolation(v pendingViolation) bool {
+	if v.StudentRkID <= 0 {
+		return true
+	}
+	payload := map[string]any{
+		"studentRkId": v.StudentRkID,
+		"kind":        v.Kind,
+		"reason":      v.Reason,
+		"monitorMode": v.MonitorMode,
+		"clientAt":    v.ClientAt,
+	}
+	bodyBytes, _ := json.Marshal(payload)
+	client := http.Client{Timeout: 5 * time.Second}
+	resp, err := client.Post(API_BASE+"/api/student/report-violation", "application/json", bytes.NewBuffer(bodyBytes))
+	if err != nil {
+		log.Printf("[VIOLATION] report failed: %v", err)
+		return false
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		log.Printf("[VIOLATION] report status %d: %s", resp.StatusCode, string(body))
+		return false
+	}
+	log.Printf("[VIOLATION] reported kind=%s student=%d", v.Kind, v.StudentRkID)
+	return true
+}
+
+func (a *App) reportViolation(kind, reason string) {
+	a.mu.Lock()
+	studentID := int64(0)
+	mode := a.dashboard.MonitorMode
+	if a.student != nil {
+		studentID = a.student.StudentID
+	}
+	a.mu.Unlock()
+	if studentID <= 0 {
+		return
+	}
+	v := pendingViolation{
+		Kind:        kind,
+		Reason:      reason,
+		MonitorMode: mode,
+		ClientAt:    time.Now().Format(time.RFC3339),
+		StudentRkID: studentID,
+	}
+	if !a.postViolation(v) {
+		a.enqueuePendingViolation(v)
+	}
+}
+
 // startLocalServer khởi chạy server lắng nghe callback nhận thông tin sinh viên từ webview
 func (a *App) startLocalServer() {
 	mux := http.NewServeMux()
@@ -392,6 +584,16 @@ func (a *App) startLocalServer() {
 		}()
 		w.Write([]byte("ok"))
 	})
+	mux.HandleFunc("/exam-clear-cache", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		if r.Method == "OPTIONS" {
+			w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
+			return
+		}
+		// Chỉ purge disk — JS trên trang exam-view tự clear storage + reload iframe.
+		go a.purgeWebViewDiskCache()
+		w.Write([]byte("ok"))
+	})
 
 	go func() {
 		_ = server.ListenAndServe()
@@ -408,26 +610,95 @@ const examViewHTML = `<!DOCTYPE html>
 <style>
 *{box-sizing:border-box;margin:0;padding:0}
 body{font-family:Segoe UI,system-ui,sans-serif;background:#1e293b;color:#f8fafc;height:100vh;display:flex;flex-direction:column}
-.bar{display:flex;align-items:center;gap:12px;padding:10px 14px;background:#0f172a;border-bottom:1px solid #334155;flex-shrink:0}
-.bar button{background:#7c3aed;color:#fff;border:none;border-radius:8px;padding:8px 14px;font-size:14px;cursor:pointer;font-weight:600}
-.bar button:hover{background:#6d28d9}
-.bar span{font-size:14px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
+.bar{display:flex;align-items:center;gap:8px;padding:10px 14px;background:#0f172a;border-bottom:1px solid #334155;flex-shrink:0}
+.bar-title{font-size:14px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;margin-right:auto;min-width:0}
+.bar button{border:none;border-radius:8px;padding:8px 12px;font-size:13px;cursor:pointer;font-weight:600;white-space:nowrap}
+.btn-back{background:#7c3aed;color:#fff}
+.btn-back:hover{background:#6d28d9}
+.btn-refresh{background:#0ea5e9;color:#fff}
+.btn-refresh:hover{background:#0284c7}
+.btn-cache{background:#f59e0b;color:#111}
+.btn-cache:hover{background:#d97706}
+.btn-cache:disabled,.btn-refresh:disabled{opacity:.65;cursor:wait}
+.hint{font-size:11px;color:#94a3b8;flex-shrink:0}
 .frame-wrap{flex:1;min-height:0;background:#fff}
 iframe{width:100%%;height:100%%;border:0;display:block}
 </style>
 </head>
 <body>
 <div class="bar">
-<button type="button" onclick="goBack()">← Quay lại</button>
-<span>%s</span>
+<button type="button" class="btn-back" onclick="goBack()">← Quay lại</button>
+<span class="bar-title">%s</span>
+<span class="hint">Nếu trang lỗi / trắng: F5 hoặc Xóa cache</span>
+<button type="button" class="btn-refresh" id="btn-refresh" onclick="refreshExam()">⟳ F5 Làm mới</button>
+<button type="button" class="btn-cache" id="btn-cache" onclick="clearExamCache()">🗑 Xóa cache</button>
 </div>
 <div class="frame-wrap">
-<iframe src="%s" title="exam-content"></iframe>
+<iframe id="exam-frame" src="%s" title="exam-content"></iframe>
 </div>
 <script>
 function goBack(){
   fetch('http://127.0.0.1:34115/exam-close').catch(function(){});
 }
+function refreshExam(){
+  var f = document.getElementById('exam-frame');
+  if (!f) return;
+  var btn = document.getElementById('btn-refresh');
+  if (btn) btn.disabled = true;
+  try {
+    f.contentWindow.location.reload();
+  } catch (e) {
+    var src = f.src;
+    f.src = 'about:blank';
+    setTimeout(function(){ f.src = src; }, 50);
+  }
+  setTimeout(function(){ if (btn) btn.disabled = false; }, 800);
+}
+async function clearExamCache(){
+  var btn = document.getElementById('btn-cache');
+  if (btn) btn.disabled = true;
+  try {
+    if (window.caches) {
+      var keys = await caches.keys();
+      await Promise.all(keys.map(function(k){ return caches.delete(k); }));
+    }
+  } catch (e) {}
+  try { localStorage.clear(); } catch (e) {}
+  try { sessionStorage.clear(); } catch (e) {}
+  try {
+    var f = document.getElementById('exam-frame');
+    if (f && f.contentWindow) {
+      try { f.contentWindow.localStorage.clear(); } catch (e) {}
+      try { f.contentWindow.sessionStorage.clear(); } catch (e) {}
+      try {
+        if (f.contentWindow.caches) {
+          var ikeys = await f.contentWindow.caches.keys();
+          await Promise.all(ikeys.map(function(k){ return f.contentWindow.caches.delete(k); }));
+        }
+      } catch (e) {}
+    }
+  } catch (e) {}
+  try {
+    await fetch('http://127.0.0.1:34115/exam-clear-cache');
+  } catch (e) {}
+  var f = document.getElementById('exam-frame');
+  if (f) {
+    try {
+      var u = new URL(f.src, window.location.href);
+      u.searchParams.set('_sc_cb', String(Date.now()));
+      f.src = u.toString();
+    } catch (e) {
+      refreshExam();
+    }
+  }
+  setTimeout(function(){ if (btn) btn.disabled = false; }, 1200);
+}
+document.addEventListener('keydown', function(e){
+  if (e.key === 'F5') {
+    e.preventDefault();
+    refreshExam();
+  }
+});
 </script>
 </body>
 </html>`
@@ -1017,6 +1288,7 @@ func (a *App) rejectUnauthorizedWifi(ssid, bssid string) {
 	a.wifiRejected = true
 	a.mu.Unlock()
 
+	a.reportViolation("wifi", fmt.Sprintf("WiFi không được phép: %s (%s)", ssid, bssid))
 	a.showQuitDialog(
 		"WiFi không được phép",
 		fmt.Sprintf("Điểm phát WiFi \"%s\" (%s) không được phép.\n\nCó thể là mạng giả mạo (hotspot trùng tên). Hãy kết nối đúng WiFi của trường rồi mở lại ứng dụng.", ssid, bssid),
@@ -1132,40 +1404,101 @@ func (a *App) connectWS() {
 		return
 	}
 	a.mu.Lock()
-	if a.wsConnected || a.student == nil {
+	if a.wsConnected || a.wsConnecting || a.student == nil {
 		a.mu.Unlock()
 		return
 	}
+	a.wsConnecting = true
 	student := a.student
 	classID := a.dashboard.ClassRkID
 	if classID <= 0 {
 		classID = student.SystemID
 	}
+	backoff := a.wsBackoff
+	if backoff <= 0 {
+		backoff = 500 * time.Millisecond
+	}
 	a.mu.Unlock()
 
 	wsUrl := fmt.Sprintf("%s/ws?role=student&studentId=%d&classId=%d", getWsUrl(API_BASE), student.StudentID, classID)
 	dialer := websocket.Dialer{HandshakeTimeout: 4 * time.Second}
 	conn, _, err := dialer.Dial(wsUrl, nil)
 	if err != nil {
+		a.mu.Lock()
+		a.wsConnecting = false
+		delay := backoff
+		next := delay * 2
+		if next > 10*time.Second {
+			next = 10 * time.Second
+		}
+		a.wsBackoff = next
+		a.mu.Unlock()
+		log.Printf("[WS] Dial failed: %v — retry in %v", err, delay)
+		time.AfterFunc(delay, func() {
+			if a.isMonitoringActive() && a.CheckLoginStatus() {
+				a.connectWS()
+			}
+		})
 		return
 	}
 
+	_ = conn.SetReadDeadline(time.Now().Add(45 * time.Second))
+	conn.SetPongHandler(func(string) error {
+		return conn.SetReadDeadline(time.Now().Add(45 * time.Second))
+	})
+
 	a.mu.Lock()
 	a.wsConn = conn
 	a.wsConnected = true
+	a.wsConnecting = false
+	a.wsBackoff = 500 * time.Millisecond
 	a.mu.Unlock()
 
 	log.Println("[WS] Connected to proctor websocket hub.")
+	a.markRunLock()
+
+	pingDone := make(chan struct{})
+	go func() {
+		ticker := time.NewTicker(15 * time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-pingDone:
+				return
+			case <-ticker.C:
+				a.wsWriteMu.Lock()
+				err := conn.WriteControl(websocket.PingMessage, []byte("ping"), time.Now().Add(5*time.Second))
+				a.wsWriteMu.Unlock()
+				if err != nil {
+					return
+				}
+				// App-level ping (một số proxy không forward WS control frames đúng).
+				_ = a.safeWriteWS(map[string]any{"event": "client:ping", "data": map[string]any{}})
+			}
+		}
+	}()
 
 	go func() {
+		defer close(pingDone)
 		defer func() {
 			a.disconnectWS(conn)
-			go func() {
-				time.Sleep(500 * time.Millisecond)
+			a.mu.Lock()
+			delay := a.wsBackoff
+			if delay <= 0 {
+				delay = 500 * time.Millisecond
+			}
+			next := delay * 2
+			if next > 10*time.Second {
+				next = 10 * time.Second
+			}
+			a.wsBackoff = next
+			a.mu.Unlock()
+			log.Printf("[WS] Disconnected — reconnect in %v", delay)
+			time.AfterFunc(delay, func() {
 				if a.isMonitoringActive() && a.CheckLoginStatus() {
 					a.connectWS()
 				}
-			}()
+			})
 		}()
 		for {
 			var msg struct {
@@ -1177,6 +1510,10 @@ func (a *App) connectWS() {
 				log.Printf("[WS] ReadJSON error: %v", err)
 				break
 			}
+			_ = conn.SetReadDeadline(time.Now().Add(45 * time.Second))
+			if msg.Event == "client:pong" {
+				continue
+			}
 			log.Printf("[WS] Received event: %s", msg.Event)
 
 			switch msg.Event {
@@ -1238,6 +1575,7 @@ func (a *App) disconnectWS(expectedConn ...*websocket.Conn) {
 		a.wsConn = nil
 	}
 	a.wsConnected = false
+	a.wsConnecting = false
 	shouldStopStreams = a.isStreamingSc || a.isStreamingCam
 	a.mu.Unlock()
 
@@ -1523,6 +1861,83 @@ func (a *App) ReturnToDashboard() {
 	runtime.WindowReloadApp(a.ctx)
 }
 
+// ReloadExamPage — F5: làm mới trang / iframe đang mở (trắc nghiệm).
+func (a *App) ReloadExamPage() {
+	guard.SuppressFor(3 * time.Second)
+	runtime.WindowExecJS(a.ctx, `
+		(function(){
+			try {
+				if (typeof window.refreshExam === 'function') { window.refreshExam(); return; }
+				var f = document.getElementById('exam-frame');
+				if (f) {
+					try { f.contentWindow.location.reload(); }
+					catch (e) { var s = f.src; f.src = 'about:blank'; setTimeout(function(){ f.src = s; }, 50); }
+					return;
+				}
+			} catch (e) {}
+			location.reload();
+		})();
+	`)
+}
+
+// ClearExamBrowserCache — xóa cache WebView (storage + disk cache) rồi làm mới trang thi.
+func (a *App) ClearExamBrowserCache() {
+	guard.SuppressFor(8 * time.Second)
+	a.purgeWebViewDiskCache()
+	runtime.WindowExecJS(a.ctx, `
+		(async function(){
+			try {
+				if (window.caches) {
+					var keys = await caches.keys();
+					await Promise.all(keys.map(function(k){ return caches.delete(k); }));
+				}
+			} catch (e) {}
+			try { localStorage.clear(); } catch (e) {}
+			try { sessionStorage.clear(); } catch (e) {}
+			try {
+				var f = document.getElementById('exam-frame');
+				if (f) {
+					try { f.contentWindow.localStorage.clear(); } catch (e) {}
+					try { f.contentWindow.sessionStorage.clear(); } catch (e) {}
+					try {
+						var u = new URL(f.src, window.location.href);
+						u.searchParams.set('_sc_cb', String(Date.now()));
+						f.src = u.toString();
+						return;
+					} catch (e) {
+						try { f.contentWindow.location.reload(); } catch (e2) {
+							var s = f.src; f.src = 'about:blank'; setTimeout(function(){ f.src = s; }, 50);
+						}
+						return;
+					}
+				}
+			} catch (e) {}
+			location.reload();
+		})();
+	`)
+}
+
+func (a *App) purgeWebViewDiskCache() {
+	if a.webviewDataPath == "" {
+		return
+	}
+	subs := []string{
+		filepath.Join("EBWebView", "Default", "Cache"),
+		filepath.Join("EBWebView", "Default", "Code Cache"),
+		filepath.Join("EBWebView", "Default", "GPUCache"),
+		filepath.Join("EBWebView", "Default", "Service Worker", "CacheStorage"),
+		filepath.Join("EBWebView", "Default", "Service Worker", "ScriptCache"),
+	}
+	for _, sub := range subs {
+		path := filepath.Join(a.webviewDataPath, sub)
+		if err := os.RemoveAll(path); err != nil {
+			log.Printf("[CACHE] purge %s: %v", path, err)
+		} else {
+			log.Printf("[CACHE] purged %s", path)
+		}
+	}
+}
+
 func isLocalExamURL(raw string) bool {
 	u, err := url.Parse(strings.TrimSpace(raw))
 	if err != nil || u.Host == "" {
@@ -1533,11 +1948,17 @@ func isLocalExamURL(raw string) bool {
 }
 
 func (a *App) openExamWebView(targetURL, title string) error {
+	return a.openExamWebViewOpts(targetURL, title, false)
+}
+
+// openExamWebViewOpts mở nội dung trong WebView.
+// forceWrap=true luôn dùng khung exam-view (có nút F5 / xóa cache) — dùng cho trắc nghiệm.
+func (a *App) openExamWebViewOpts(targetURL, title string, forceWrap bool) error {
 	targetURL = strings.TrimSpace(targetURL)
 	if targetURL == "" {
 		return errors.New("không có nội dung để mở")
 	}
-	if isLocalExamURL(targetURL) {
+	if forceWrap || isLocalExamURL(targetURL) {
 		wrapper := fmt.Sprintf(
 			"http://127.0.0.1:34115/exam-view?url=%s&title=%s",
 			url.QueryEscape(targetURL),
@@ -1547,7 +1968,7 @@ func (a *App) openExamWebView(targetURL, title string) error {
 		runtime.WindowExecJS(a.ctx, fmt.Sprintf("window.location.href = %q", wrapper))
 		return nil
 	}
-	// Trang thi bên ngoài: mở trực tiếp trong WebView (first-party cookies → giữ phiên đăng nhập).
+	// Trang thi bên ngoài (đề/tài nguyên): mở trực tiếp để giữ first-party cookies.
 	guard.SuppressFor(5 * time.Second)
 	runtime.WindowExecJS(a.ctx, fmt.Sprintf("window.location.href = %q", targetURL))
 	return nil
@@ -1639,7 +2060,8 @@ func (a *App) OpenExamQuiz() error {
 	if err != nil {
 		return err
 	}
-	return a.openExamWebView(viewURL, "Làm trắc nghiệm")
+	// Luôn mở trong khung có nút F5 / Xóa cache để SV tự xử lý khi trang lỗi.
+	return a.openExamWebViewOpts(viewURL, "Làm trắc nghiệm", true)
 }
 
 func (a *App) OpenExamResource(fileID uint) error {