tam 2

2026-07-13 09:04:09 +07:00
parent 719704f19e
commit 8803cd622a
22 changed files with 1322 additions and 121 deletions
--- a/client/app.go
+++ b/client/app.go
@@ -125,8 +125,13 @@ type App struct {
 	sessionPath       string
 	statsPath         string
 	webviewDataPath   string
+	pendingViolPath   string
+	runLockPath       string
 	wsConn            *websocket.Conn
 	wsConnected       bool
+	wsConnecting      bool
+	wsBackoff         time.Duration
+	wsWriteMu         sync.Mutex
 	wifiSSID          string
 	wifiBSSID         string
 	allowedApps       string
@@ -152,7 +157,6 @@ type App struct {
 	chatUnread        int
 	replyStaffID      uint
 	fetchAppsMu       sync.Mutex
-	wsWriteMu         sync.Mutex
 }

 type LocalStats struct {
@@ -216,6 +220,8 @@ func NewApp() *App {
 		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 {
--- a/client/frontend/src/main.js
+++ b/client/frontend/src/main.js
@@ -413,7 +413,7 @@ function renderExamPanel() {
      <div class="card-title-row">
        <div class="card-title">📝 ${ex.examName || 'Phòng thi'}</div>
      </div>
-      <p class="exam-panel-desc">Đề PDF và tài nguyên xem ngay trong app. Link trắc nghiệm mở trang thi — xong thì menu <strong>Simple Care → Về trang chính</strong> (Ctrl+H).</p>
+      <p class="exam-panel-desc">Đề PDF và tài nguyên xem trong app. Trắc nghiệm có nút <strong>F5</strong> / <strong>Xóa cache</strong> trên thanh công cụ. Xong: menu <strong>Simple Care → Về trang chính</strong> (Ctrl+H).</p>
      <div class="exam-panel-actions">
        ${paperBtn}
        ${quizBtn}
--- a/client/internal/guard/guard_darwin.go
+++ b/client/internal/guard/guard_darwin.go
@@ -11,7 +11,7 @@ import (

 var (
 	guardOnce               sync.Once
-	guardViolation           func(string)
+	guardViolation           func(kind, reason string)
 	guardStop               chan struct{}
 	suppressMu              sync.Mutex
 	suppressViolationsUntil time.Time
@@ -36,8 +36,8 @@ func violationsSuppressed() bool {
 	return time.Now().Before(suppressViolationsUntil)
 }

-// Start giám sát môi trường macOS — vi phạm thì gọi onViolation (đa màn hình).
-func Start(onViolation func(reason string)) {
+// Start giám sát môi trường macOS — vi phạm thì gọi onViolation(kind, reason).
+func Start(onViolation func(kind, reason string)) {
 	guardOnce.Do(func() {
 		if onViolation == nil {
 			return
@@ -46,7 +46,7 @@ func Start(onViolation func(reason string)) {
 		guardStop = make(chan struct{})

 		if screenshot.NumActiveDisplays() > 1 {
-			onViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
+			onViolation("multi_monitor", "Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
 			return
 		}

@@ -83,7 +83,7 @@ func checkEnvironment() {
 		return
 	}
 	if n := screenshot.NumActiveDisplays(); n > 1 {
-		guardViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
+		guardViolation("multi_monitor", "Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
 		return
 	}
 }
--- a/client/internal/guard/guard_linux.go
+++ b/client/internal/guard/guard_linux.go
@@ -11,7 +11,7 @@ import (

 var (
 	guardOnce               sync.Once
-	guardViolation          func(string)
+	guardViolation          func(kind, reason string)
 	guardStop               chan struct{}
 	suppressMu              sync.Mutex
 	suppressViolationsUntil time.Time
@@ -37,7 +37,7 @@ func violationsSuppressed() bool {
 }

 // Start monitors the Linux desktop environment (multi-display check)
-func Start(onViolation func(reason string)) {
+func Start(onViolation func(kind, reason string)) {
 	guardOnce.Do(func() {
 		if onViolation == nil {
 			return
@@ -46,7 +46,7 @@ func Start(onViolation func(reason string)) {
 		guardStop = make(chan struct{})

 		if screenshot.NumActiveDisplays() > 1 {
-			onViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
+			onViolation("multi_monitor", "Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
 			return
 		}

@@ -84,7 +84,7 @@ func checkEnvironment() {
 		return
 	}
 	if n := screenshot.NumActiveDisplays(); n > 1 {
-		guardViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
+		guardViolation("multi_monitor", "Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
 		return
 	}
 }
--- a/client/internal/guard/guard_other.go
+++ b/client/internal/guard/guard_other.go
@@ -4,6 +4,6 @@ package guard

 import "time"

-func Start(onViolation func(reason string)) {}
+func Start(onViolation func(kind, reason string)) {}
 func Stop() {}
 func SuppressFor(_ time.Duration) {}
--- a/client/internal/guard/guard_windows.go
+++ b/client/internal/guard/guard_windows.go
@@ -73,7 +73,7 @@ type msg struct {

 var (
 	guardOnce               sync.Once
-	guardViolation           func(string)
+	guardViolation          func(kind, reason string)
 	guardStop               chan struct{}
 	guardBaselineUser       string
 	guardBaselineSession    uint32
@@ -102,8 +102,8 @@ func violationsSuppressed() bool {
 	return time.Now().Before(suppressViolationsUntil)
 }

-// Start giám sát môi trường Windows — vi phạm thì gọi onViolation (đổi user, đa màn hình, đổi desktop ảo).
-func Start(onViolation func(reason string)) {
+// Start giám sát môi trường Windows — vi phạm thì gọi onViolation(kind, reason).
+func Start(onViolation func(kind, reason string)) {
 	guardOnce.Do(func() {
 		if onViolation == nil {
 			return
@@ -114,7 +114,7 @@ func Start(onViolation func(reason string)) {
 		guardBaselineSession = currentSessionID()

 		if monitorCount() > 1 {
-			onViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
+			onViolation("multi_monitor", "Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
 			return
 		}

@@ -147,27 +147,27 @@ func checkEnvironment() {
 		return
 	}
 	if n := monitorCount(); n > 1 {
-		guardViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
+		guardViolation("multi_monitor", "Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
 		return
 	}
 	user := currentUsername()
 	if user != "" && guardBaselineUser != "" && user != guardBaselineUser {
-		guardViolation("Phát hiện đổi tài khoản Windows. Ứng dụng sẽ thoát.")
+		guardViolation("user_switch", "Phát hiện đổi tài khoản Windows. Ứng dụng sẽ thoát.")
 		return
 	}
 	sid := currentSessionID()
 	if sid != 0 && guardBaselineSession != 0 && sid != guardBaselineSession {
-		guardViolation("Phiên đăng nhập Windows đã thay đổi. Ứng dụng sẽ thoát.")
+		guardViolation("session_change", "Phiên đăng nhập Windows đã thay đổi. Ứng dụng sẽ thoát.")
 	}
 }

-func triggerViolation(reason string) {
+func triggerViolation(kind, reason string) {
 	if violationsSuppressed() {
 		log.Printf("[GUARD] suppressed: %s", reason)
 		return
 	}
 	if guardViolation != nil {
-		guardViolation(reason)
+		guardViolation(kind, reason)
 	}
 }

@@ -262,7 +262,7 @@ func guardWndProc(hwnd, msg, wParam, lParam uintptr) uintptr {
 	case wmWtsSessionChange:
 		switch uint32(wParam) {
 		case wtsSessionLock, wtsSessionLogoff, wtsConsoleDisconnect, wtsRemoteDisconnect:
-			triggerViolation("Phiên Windows bị khóa, đăng xuất hoặc chuyển người dùng. Ứng dụng sẽ thoát.")
+			triggerViolation("session_change", "Phiên Windows bị khóa, đăng xuất hoặc chuyển người dùng. Ứng dụng sẽ thoát.")
 		}
 	}
 	r, _, _ := procDefWindowProcW.Call(hwnd, msg, wParam, lParam)
@@ -271,7 +271,7 @@ func guardWndProc(hwnd, msg, wParam, lParam uintptr) uintptr {

 func desktopSwitchCallback(hWinEventHook, event, hwnd, idObject, idChild, idEventThread, dwmsEventTime uintptr) uintptr {
 	if event == eventSystemDesktopSwitch {
-		triggerViolation("Không được chuyển Desktop ảo (Win+Tab). Ứng dụng sẽ thoát.")
+		triggerViolation("virtual_desktop", "Không được chuyển Desktop ảo (Win+Tab). Ứng dụng sẽ thoát.")
 	}
 	return 0
 }
--- a/client/main.go
+++ b/client/main.go
@@ -1,6 +1,7 @@
 package main

 import (
+	"context"
 	"embed"
 	"log"
 	"os"
@@ -46,6 +47,12 @@ func main() {
 	fileMenu.AddText("Về trang chính", keys.CmdOrCtrl("h"), func(_ *menu.CallbackData) {
 		app.ReturnToDashboard()
 	})
+	fileMenu.AddText("Làm mới trang (F5)", keys.Key("f5"), func(_ *menu.CallbackData) {
+		app.ReloadExamPage()
+	})
+	fileMenu.AddText("Xóa cache trình duyệt", keys.CmdOrCtrl("Delete"), func(_ *menu.CallbackData) {
+		app.ClearExamBrowserCache()
+	})

 	// Create application with options
 	err := wails.Run(&options.App{
@@ -58,6 +65,9 @@ func main() {
 		},
 		BackgroundColour: &options.RGBA{R: 27, G: 38, B: 54, A: 1},
 		OnStartup:        app.startup,
+		OnBeforeClose: func(ctx context.Context) (prevent bool) {
+			return app.HandleBeforeClose()
+		},
 		Windows: &windows.Options{
 			WebviewUserDataPath: app.webviewDataPath,
 		},
--- a/management/src/api.ts
+++ b/management/src/api.ts
@@ -381,6 +381,31 @@ export interface StudentSessionLogItem {
  lastActiveAt?: string;
 }

+export interface StudentViolationItem {
+  id: number;
+  studentRkId: number;
+  studentCode: string;
+  fullName: string;
+  classRkId: number;
+  kind: string;
+  reason: string;
+  monitorMode: string;
+  clientAt?: string;
+  createdAt: string;
+}
+
+export const VIOLATION_KIND_OPTIONS = [
+  { value: '', label: 'Tất cả loại' },
+  { value: 'app_closed', label: 'Tự đóng app' },
+  { value: 'unclean_shutdown', label: 'Tắt đột ngột' },
+  { value: 'multi_monitor', label: 'Nhiều màn hình' },
+  { value: 'user_switch', label: 'Đổi user' },
+  { value: 'session_change', label: 'Khóa / đổi phiên' },
+  { value: 'virtual_desktop', label: 'Desktop ảo' },
+  { value: 'wifi', label: 'WiFi trái phép' },
+  { value: 'guard', label: 'Vi phạm môi trường (cũ)' },
+] as const;
+
 export const api = {
  getStats: async (): Promise<StatsResponse> => {
    const res = await staffFetch('/stats');
@@ -716,6 +741,30 @@ export const apiFetchClassSessionLogs = async (
  return res.json();
 };

+export const apiFetchClassViolations = async (
+  rkId: number,
+  date: string,
+  kind = ''
+): Promise<{ data: StudentViolationItem[]; date: string }> => {
+  const params = new URLSearchParams({ date });
+  if (kind) params.set('kind', kind);
+  const res = await staffFetch(`/classes/${rkId}/violations?${params}`);
+  if (!res.ok) throw new Error('Failed to fetch class violations');
+  return res.json();
+};
+
+export const apiFetchExamViolations = async (
+  examId: number,
+  date: string,
+  kind = ''
+): Promise<{ data: StudentViolationItem[]; date: string }> => {
+  const params = new URLSearchParams({ date });
+  if (kind) params.set('kind', kind);
+  const res = await staffFetch(`/exam-rooms/${examId}/violations?${params}`);
+  if (!res.ok) throw new Error('Failed to fetch exam violations');
+  return res.json();
+};
+
 export const apiFetchOnlineStudents = async (rkId: number): Promise<{ onlineStudentIds: number[] }> => {
  const res = await staffFetch(`/classes/${rkId}/online-students`);
  if (!res.ok) throw new Error('Failed to fetch online students list');
--- a/management/src/components/ChatWidget.tsx
+++ b/management/src/components/ChatWidget.tsx
@@ -3,7 +3,7 @@ import { createPortal } from 'react-dom';
 import { apiChat, type ChatConversation, type ChatMessage, type ChatStudent } from '../api';
 import { type StaffChatOpenDetail } from '../chatEvents';
 import { useAuth } from '../auth/AuthContext';
-import { onStaffChatMessage, playChatSound } from '../hooks/useStaffChatSocket';
+import { onStaffChatMessage, onStudentViolation, playChatSound, kindLabel } from '../hooks/useStaffChatSocket';

 export function ChatWidget() {
  const { staff } = useAuth();
@@ -83,6 +83,13 @@ export function ChatWidget() {
    return () => { off(); };
  }, [handleIncoming]);

+  useEffect(() => {
+    return onStudentViolation((v) => {
+      const name = v.studentName || v.studentCode || `SV #${v.studentId}`;
+      showToast(`⚠ ${kindLabel(v.kind)}`, `${name}: ${v.reason || 'Vi phạm giám sát'}`);
+    });
+  }, []);
+
  useEffect(() => {
    const onOpen = (e: Event) => {
      const detail = (e as CustomEvent<StaffChatOpenDetail>).detail;
@@ -152,7 +159,7 @@ export function ChatWidget() {
  const dock = (
    <div className="chat-dock">
      {toast && (
-        <div className="chat-toast" role="status">
+        <div className={`chat-toast ${toast.title.startsWith('⚠') ? 'chat-toast-alert' : ''}`} role="status">
          <strong>{toast.title}</strong>
          <span>{toast.body}</span>
        </div>
--- a/management/src/components/ClassWorkspace.tsx
+++ b/management/src/components/ClassWorkspace.tsx
@@ -23,6 +23,8 @@ import { AttendancePanel } from './AttendancePanel';
 import { StudentDetailModal } from './StudentDetailModal';
 import { ExamGridProctor } from './ExamGridProctor';
 import { AppPoolModal } from './AppPoolModal';
+import { onStudentPresence } from '../hooks/useStaffChatSocket';
+import { ViolationsPanel } from './ViolationsPanel';
 import { AppTemplatePickerModal } from './AppTemplatePickerModal';
 import { mergeKeywordCSV } from '../utils/appKeywords';
 import { WorkspaceSeatingChart } from './WorkspaceSeatingChart';
@@ -52,7 +54,7 @@ export const ClassWorkspace: React.FC<ClassWorkspaceProps> = ({ classId, sourceT
  const [loading, setLoading] = useState(true);
  const [logsLoading, setLogsLoading] = useState(false);
  const [savingApps, setSavingApps] = useState(false);
-  const [activeSubTab, setActiveSubTab] = useState<'roster' | 'grid' | 'logs' | 'attendance'>('roster');
+  const [activeSubTab, setActiveSubTab] = useState<'roster' | 'grid' | 'logs' | 'attendance' | 'violations'>('roster');
  const [configOpen, setConfigOpen] = useState(false);
  const [configTab, setConfigTab] = useState<'apps' | 'schedule'>('schedule');
  const [appPoolOpen, setAppPoolOpen] = useState(false);
@@ -144,10 +146,21 @@ export const ClassWorkspace: React.FC<ClassWorkspaceProps> = ({ classId, sourceT
    const interval = setInterval(() => {
      fetchOnlineStatus();
      fetchLogs(logDate, logPeriod);
-    }, 5000);
+    }, 8000);
    return () => clearInterval(interval);
  }, [classId, logDate, logPeriod]);

+  useEffect(() => {
+    return onStudentPresence(({ studentId, online }) => {
+      setOnlineIds((prev) => {
+        const has = prev.includes(studentId);
+        if (online && !has) return [...prev, studentId];
+        if (!online && has) return prev.filter((id) => id !== studentId);
+        return prev;
+      });
+    });
+  }, []);
+
  useEffect(() => {
    loadLogShifts(logDate);
    if (activeSubTab === 'logs') {
@@ -400,6 +413,12 @@ export const ClassWorkspace: React.FC<ClassWorkspaceProps> = ({ classId, sourceT
              >
                Nhật ký theo ca
              </button>
+              <button 
+                className={`tab-sub-btn ${activeSubTab === 'violations' ? 'active' : ''}`}
+                onClick={() => setActiveSubTab('violations')}
+              >
+                Vi phạm
+              </button>
              <button 
                className={`tab-sub-btn ${activeSubTab === 'attendance' ? 'active' : ''}`}
                onClick={() => setActiveSubTab('attendance')}
@@ -410,7 +429,7 @@ export const ClassWorkspace: React.FC<ClassWorkspaceProps> = ({ classId, sourceT
            </div>

            {/* Student Search */}
-            {activeSubTab !== 'attendance' && activeSubTab !== 'grid' && <div className="search-input-wrapper">
+            {activeSubTab !== 'attendance' && activeSubTab !== 'grid' && activeSubTab !== 'violations' && <div className="search-input-wrapper">
              <input
                type="text"
                className="search-input"
@@ -425,9 +444,11 @@ export const ClassWorkspace: React.FC<ClassWorkspaceProps> = ({ classId, sourceT
          <div className="divider" style={{ opacity: 0.3, margin: '0.25rem 0' }}></div>
          </div>

-          <div className={`workspace-panel-body ${activeSubTab === 'attendance' || activeSubTab === 'logs' || activeSubTab === 'grid' || activeSubTab === 'roster' ? 'workspace-panel-fill' : ''}`}>
+          <div className={`workspace-panel-body ${activeSubTab === 'attendance' || activeSubTab === 'logs' || activeSubTab === 'grid' || activeSubTab === 'roster' || activeSubTab === 'violations' ? 'workspace-panel-fill' : ''}`}>
          {activeSubTab === 'attendance' ? (
            <AttendancePanel classId={classId} />
+          ) : activeSubTab === 'violations' ? (
+            <ViolationsPanel mode="class" classId={classId} />
          ) : activeSubTab === 'grid' ? (
            <ExamGridProctor
              students={students.map((s) => ({
--- a/management/src/components/ExamGridProctor.tsx
+++ b/management/src/components/ExamGridProctor.tsx
@@ -56,6 +56,15 @@ export const ExamGridProctor: React.FC<ExamGridProctorProps> = ({
    const wsUrl = getWsUrl('/ws?role=teacher');
    let closed = false;
    let retryTimer: ReturnType<typeof setTimeout> | null = null;
+    let pingTimer: ReturnType<typeof setInterval> | null = null;
+    let attempt = 0;
+
+    const clearPing = () => {
+      if (pingTimer) {
+        clearInterval(pingTimer);
+        pingTimer = null;
+      }
+    };

    const connect = () => {
      if (closed) return;
@@ -64,11 +73,21 @@ export const ExamGridProctor: React.FC<ExamGridProctorProps> = ({
      wsRef.current = ws;
      subscribedRef.current = new Set();

-      ws.onopen = () => syncSubscriptions(ws);
+      ws.onopen = () => {
+        attempt = 0;
+        syncSubscriptions(ws);
+        clearPing();
+        pingTimer = setInterval(() => {
+          if (ws.readyState === WebSocket.OPEN) {
+            ws.send(JSON.stringify({ event: 'client:ping', data: {} }));
+          }
+        }, 15000);
+      };

      ws.onmessage = (event) => {
        try {
          const msg = JSON.parse(event.data);
+          if (msg.event === 'client:pong') return;
          if (msg.event === 'teacher:screenshot-stream-frame') {
            const { studentId, imageBuffer } = msg.data;
            setScreenFrames((prev) => ({ ...prev, [studentId]: imageBuffer }));
@@ -94,9 +113,11 @@ export const ExamGridProctor: React.FC<ExamGridProctorProps> = ({
      };

      ws.onclose = () => {
+        clearPing();
        subscribedRef.current = new Set();
        if (!closed) {
-          retryTimer = setTimeout(connect, 3000);
+          const delay = Math.min(1000 * 2 ** Math.min(attempt++, 4), 10000);
+          retryTimer = setTimeout(connect, delay);
        }
      };
    };
@@ -105,6 +126,7 @@ export const ExamGridProctor: React.FC<ExamGridProctorProps> = ({

    return () => {
      closed = true;
+      clearPing();
      if (retryTimer) clearTimeout(retryTimer);
      const ws = wsRef.current;
      if (ws?.readyState === WebSocket.OPEN) {
--- a/management/src/components/ExamRoomWorkspace.tsx
+++ b/management/src/components/ExamRoomWorkspace.tsx
@@ -20,6 +20,8 @@ import { StudentDetailModal } from './StudentDetailModal';
 import { fmtTime, localInputToISO, toLocalInput } from './ExamsTab';
 import { ExamGridProctor } from './ExamGridProctor';
 import { WorkspaceSeatingChart } from './WorkspaceSeatingChart';
+import { onStudentPresence } from '../hooks/useStaffChatSocket';
+import { ViolationsPanel } from './ViolationsPanel';

 const EXAM_APP_SUGGESTIONS = [...new Set([...BASE_APP_SUGGESTIONS, 'msedge', 'edge', 'acrobat', 'foxit'])];

@@ -88,7 +90,7 @@ export const ExamRoomWorkspace: React.FC<Props> = ({ examId, onBack }) => {
  const [onlineIds, setOnlineIds] = useState<number[]>([]);
  const [searchQuery, setSearchQuery] = useState('');
  const [selectedStudent, setSelectedStudent] = useState<StudentItem | null>(null);
-  const [activeSubTab, setActiveSubTab] = useState<'roster' | 'detail' | 'submissions' | 'grid'>('roster');
+  const [activeSubTab, setActiveSubTab] = useState<'roster' | 'detail' | 'submissions' | 'grid' | 'violations'>('roster');
  const [configOpen, setConfigOpen] = useState(false);
  const [configTab, setConfigTab] = useState<'info' | 'apps' | 'papers'>('info');
  const [papersModalOpen, setPapersModalOpen] = useState(false);
@@ -163,10 +165,23 @@ export const ExamRoomWorkspace: React.FC<Props> = ({ examId, onBack }) => {

  useEffect(() => {
    fetchOnline();
-    const t = setInterval(fetchOnline, 5000);
+    const t = setInterval(fetchOnline, 8000);
    return () => clearInterval(t);
  }, [fetchOnline]);

+  useEffect(() => {
+    const roster = new Set(students.map((s) => s.studentRkId));
+    return onStudentPresence(({ studentId, online }) => {
+      if (!roster.has(studentId)) return;
+      setOnlineIds((prev) => {
+        const has = prev.includes(studentId);
+        if (online && !has) return [...prev, studentId];
+        if (!online && has) return prev.filter((id) => id !== studentId);
+        return prev;
+      });
+    });
+  }, [students]);
+
  useEffect(() => {
    if (!studentPickerOpen || !searchQ.trim()) {
      if (!studentPickerOpen) setSearchHits([]);
@@ -448,6 +463,12 @@ export const ExamRoomWorkspace: React.FC<Props> = ({ examId, onBack }) => {
  };

  const handlePublish = async () => {
+    if (!quizUrl.trim()) {
+      const ok = confirm(
+        'Phòng thi chưa có link trắc nghiệm.\n\nBạn có chắc chắn muốn đẩy phòng thi không có phần thi trắc nghiệm không?'
+      );
+      if (!ok) return;
+    }
    setErr(''); setMsg('');
    try {
      await apiExam.publish(examId);
@@ -880,11 +901,18 @@ export const ExamRoomWorkspace: React.FC<Props> = ({ examId, onBack }) => {
                  >
                    Bài nộp ({submissions.length})
                  </button>
+                  <button
+                    type="button"
+                    className={`tab-sub-btn ${activeSubTab === 'violations' ? 'active' : ''}`}
+                    onClick={() => setActiveSubTab('violations')}
+                  >
+                    Vi phạm
+                  </button>
                </div>
              </div>

              <div style={{ display: 'flex', alignItems: 'center', gap: '0.5rem', flexWrap: 'wrap' }}>
-                {activeSubTab !== 'submissions' && activeSubTab !== 'grid' && (
+                {activeSubTab !== 'submissions' && activeSubTab !== 'grid' && activeSubTab !== 'violations' && (
                  <div className="search-input-wrapper">
                    <input
                      type="text"
@@ -1014,6 +1042,8 @@ export const ExamRoomWorkspace: React.FC<Props> = ({ examId, onBack }) => {
                  )}
                </div>
              </div>
+            ) : activeSubTab === 'violations' ? (
+              <ViolationsPanel mode="exam" examId={examId} />
            ) : (
              <div className="session-logs-panel">
                {submissions.length > 0 && (
--- a/management/src/components/ProctorStreamPanels.tsx
+++ b/management/src/components/ProctorStreamPanels.tsx
@@ -33,6 +33,8 @@ export const ProctorStreamPanels: React.FC<ProctorStreamPanelsProps> = ({
  useEffect(() => {
    const wsUrl = getWsUrl('/ws?role=teacher');
    let retryTimer: ReturnType<typeof setTimeout> | null = null;
+    let pingTimer: ReturnType<typeof setInterval> | null = null;
+    let attempt = 0;

    intentionalClose.current = false;
    hasOpened.current = false;
@@ -50,6 +52,13 @@ export const ProctorStreamPanels: React.FC<ProctorStreamPanelsProps> = ({
      }
    };

+    const clearPing = () => {
+      if (pingTimer) {
+        clearInterval(pingTimer);
+        pingTimer = null;
+      }
+    };
+
    const connect = () => {
      if (intentionalClose.current) return;

@@ -57,15 +66,23 @@ export const ProctorStreamPanels: React.FC<ProctorStreamPanelsProps> = ({
      wsRef.current = ws;

      ws.onopen = () => {
+        attempt = 0;
        hasOpened.current = true;
        setStreaming(true);
        setErrorMessage(null);
        ws.send(JSON.stringify({ event: 'teacher:subscribe', data: { studentId } }));
+        clearPing();
+        pingTimer = setInterval(() => {
+          if (ws.readyState === WebSocket.OPEN) {
+            ws.send(JSON.stringify({ event: 'client:ping', data: {} }));
+          }
+        }, 15000);
      };

      ws.onmessage = (event) => {
        try {
          const msg = JSON.parse(event.data);
+          if (msg.event === 'client:pong') return;
          if (msg.event === 'teacher:screenshot-stream-frame' && msg.data.studentId === studentId) {
            setScreenFrame(msg.data.imageBuffer);
            markStreaming();
@@ -86,6 +103,7 @@ export const ProctorStreamPanels: React.FC<ProctorStreamPanelsProps> = ({
      ws.onerror = () => {};

      ws.onclose = () => {
+        clearPing();
        if (intentionalClose.current) return;
        setStreaming(false);
        if (!hasOpened.current && !hasFrames.current) {
@@ -93,7 +111,8 @@ export const ProctorStreamPanels: React.FC<ProctorStreamPanelsProps> = ({
        } else {
          setErrorMessage('Mất kết nối giám sát — đang thử lại...');
        }
-        retryTimer = setTimeout(connect, 3000);
+        const delay = Math.min(1000 * 2 ** Math.min(attempt++, 4), 10000);
+        retryTimer = setTimeout(connect, delay);
      };
    };

@@ -101,6 +120,7 @@ export const ProctorStreamPanels: React.FC<ProctorStreamPanelsProps> = ({

    return () => {
      intentionalClose.current = true;
+      clearPing();
      if (retryTimer) clearTimeout(retryTimer);
      if (wsRef.current?.readyState === WebSocket.OPEN) {
        wsRef.current.send(JSON.stringify({ event: 'teacher:unsubscribe', data: { studentId } }));
--- a/management/src/components/ViolationsPanel.tsx
+++ b/management/src/components/ViolationsPanel.tsx
@@ -0,0 +1,127 @@
+import React, { useCallback, useEffect, useState } from 'react';
+import {
+  apiFetchClassViolations,
+  apiFetchExamViolations,
+  VIOLATION_KIND_OPTIONS,
+  type StudentViolationItem,
+} from '../api';
+import { kindLabel } from '../hooks/useStaffChatSocket';
+
+type Props =
+  | { mode: 'class'; classId: number }
+  | { mode: 'exam'; examId: number };
+
+function todayLocal(): string {
+  const d = new Date();
+  const pad = (n: number) => String(n).padStart(2, '0');
+  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
+}
+
+function formatTime(iso?: string): string {
+  if (!iso) return '—';
+  const d = new Date(iso);
+  if (Number.isNaN(d.getTime())) return iso;
+  return d.toLocaleString('vi-VN');
+}
+
+export const ViolationsPanel: React.FC<Props> = (props) => {
+  const [date, setDate] = useState(todayLocal);
+  const [kind, setKind] = useState('');
+  const [rows, setRows] = useState<StudentViolationItem[]>([]);
+  const [loading, setLoading] = useState(false);
+  const [err, setErr] = useState('');
+
+  const load = useCallback(async () => {
+    setLoading(true);
+    setErr('');
+    try {
+      const res =
+        props.mode === 'class'
+          ? await apiFetchClassViolations(props.classId, date, kind)
+          : await apiFetchExamViolations(props.examId, date, kind);
+      setRows(res.data || []);
+    } catch (e: any) {
+      setErr(e?.message || 'Không tải được danh sách vi phạm');
+      setRows([]);
+    } finally {
+      setLoading(false);
+    }
+  }, [props, date, kind]);
+
+  useEffect(() => {
+    void load();
+  }, [load]);
+
+  return (
+    <div className="session-logs-panel" style={{ display: 'flex', flexDirection: 'column', gap: '0.75rem', height: '100%' }}>
+      <div className="attendance-toolbar" style={{ marginBottom: 0, flexWrap: 'wrap' }}>
+        <label className="attendance-field">
+          <span>Ngày</span>
+          <input type="date" className="search-input" style={{ padding: '0.5rem 0.75rem' }} value={date} onChange={(e) => setDate(e.target.value)} />
+        </label>
+        <label className="attendance-field">
+          <span>Loại</span>
+          <select className="select-filter" value={kind} onChange={(e) => setKind(e.target.value)}>
+            {VIOLATION_KIND_OPTIONS.map((o) => (
+              <option key={o.value || 'all'} value={o.value}>{o.label}</option>
+            ))}
+          </select>
+        </label>
+        <button type="button" className="btn btn-secondary btn-sm" onClick={() => void load()} disabled={loading}>
+          {loading ? 'Đang tải...' : 'Làm mới'}
+        </button>
+        <span style={{ marginLeft: 'auto', fontSize: '0.82rem', color: 'var(--text-muted)', fontWeight: 600 }}>
+          {rows.length} vi phạm
+        </span>
+      </div>
+
+      {err && <div className="form-error" style={{ margin: 0 }}>{err}</div>}
+
+      <div className="attendance-table-scroll table-wrapper" style={{ border: 'none', flex: 1, overflowY: 'auto' }}>
+        {loading && rows.length === 0 ? (
+          <div className="empty-state" style={{ minHeight: '220px' }}>
+            <div className="sync-spinner" style={{ width: '32px', height: '32px' }} />
+            <p style={{ marginTop: '0.5rem' }}>Đang tải vi phạm...</p>
+          </div>
+        ) : rows.length === 0 ? (
+          <div className="empty-state" style={{ minHeight: '220px' }}>
+            <p>Không có vi phạm trong ngày đã chọn.</p>
+          </div>
+        ) : (
+          <table className="data-table">
+            <thead>
+              <tr>
+                <th>Thời gian</th>
+                <th>Sinh viên</th>
+                <th>Mã SV</th>
+                <th>Loại</th>
+                <th>Chi tiết</th>
+                <th>Chế độ</th>
+              </tr>
+            </thead>
+            <tbody>
+              {rows.map((r) => (
+                <tr key={r.id}>
+                  <td style={{ whiteSpace: 'nowrap', fontFamily: 'monospace', fontSize: '0.8rem' }}>
+                    {formatTime(r.createdAt || r.clientAt)}
+                  </td>
+                  <td style={{ fontWeight: 600 }}>{r.fullName || '—'}</td>
+                  <td><code>{r.studentCode || r.studentRkId}</code></td>
+                  <td>
+                    <span className="badge badge-warning" style={{ fontSize: '0.72rem' }}>
+                      {kindLabel(r.kind)}
+                    </span>
+                  </td>
+                  <td style={{ maxWidth: 360, fontSize: '0.85rem' }} title={r.reason}>
+                    {r.reason}
+                  </td>
+                  <td style={{ fontSize: '0.8rem', color: 'var(--text-muted)' }}>{r.monitorMode || '—'}</td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        )}
+      </div>
+    </div>
+  );
+};
--- a/management/src/hooks/useStaffChatSocket.ts
+++ b/management/src/hooks/useStaffChatSocket.ts
@@ -1,18 +1,59 @@
 import { useCallback, useEffect, useRef } from 'react';
 import { type ChatMessage, getWsUrl } from '../api';
 import { useAuth } from '../auth/AuthContext';
-import { playChatSound } from '../utils/notifySound';
+import { playChatSound, playAlertSound } from '../utils/notifySound';

 type ChatIncomingHandler = (msg: ChatMessage) => void;
+export type PresenceUpdate = { studentId: number; online: boolean; classId?: number };
+export type StudentViolationEvent = {
+  studentId: number;
+  studentName?: string;
+  studentCode?: string;
+  kind: string;
+  reason: string;
+  monitorMode?: string;
+  classId?: number;
+};

-const handlers = new Set<ChatIncomingHandler>();
+const chatHandlers = new Set<ChatIncomingHandler>();
+const presenceHandlers = new Set<(p: PresenceUpdate) => void>();
+const violationHandlers = new Set<(v: StudentViolationEvent) => void>();

 export function onStaffChatMessage(handler: ChatIncomingHandler): () => void {
-  handlers.add(handler);
-  return () => { handlers.delete(handler); };
+  chatHandlers.add(handler);
+  return () => { chatHandlers.delete(handler); };
 }

-/** WebSocket luôn bật khi đã login — nhận tin sinh viên realtime */
+export function onStudentPresence(handler: (p: PresenceUpdate) => void): () => void {
+  presenceHandlers.add(handler);
+  return () => { presenceHandlers.delete(handler); };
+}
+
+export function onStudentViolation(handler: (v: StudentViolationEvent) => void): () => void {
+  violationHandlers.add(handler);
+  return () => { violationHandlers.delete(handler); };
+}
+
+function scheduleBackoff(attempt: number): number {
+  const base = Math.min(1000 * 2 ** Math.min(attempt, 4), 10000);
+  return base + Math.floor(Math.random() * 250);
+}
+
+export function kindLabel(kind: string): string {
+  switch (kind) {
+    case 'app_closed': return 'Tự đóng app';
+    case 'unclean_shutdown': return 'Tắt đột ngột';
+    case 'multi_monitor': return 'Nhiều màn hình';
+    case 'user_switch': return 'Đổi user';
+    case 'session_change': return 'Khóa / đổi phiên';
+    case 'virtual_desktop': return 'Desktop ảo';
+    case 'wifi': return 'WiFi trái phép';
+    case 'guard': return 'Vi phạm môi trường';
+    default: return kind || 'Vi phạm';
+  }
+}
+
+/** WebSocket luôn bật khi đã login — chat + presence + violation + keepalive. */
 export function StaffChatSocket() {
  const { staff, token } = useAuth();
  const staffIdRef = useRef(0);
@@ -21,8 +62,8 @@ export function StaffChatSocket() {
    staffIdRef.current = staff?.id ?? 0;
  }, [staff?.id]);

-  const dispatch = useCallback((msg: ChatMessage) => {
-    handlers.forEach((h) => h(msg));
+  const dispatchChat = useCallback((msg: ChatMessage) => {
+    chatHandlers.forEach((h) => h(msg));
  }, []);

  useEffect(() => {
@@ -31,26 +72,74 @@ export function StaffChatSocket() {
    const wsUrl = getWsUrl(`/ws?role=teacher&staffId=${staff.id}`);
    let ws: WebSocket | null = null;
    let retryTimer: ReturnType<typeof setTimeout> | null = null;
+    let pingTimer: ReturnType<typeof setInterval> | null = null;
    let closed = false;
+    let attempt = 0;
+
+    const clearPing = () => {
+      if (pingTimer) {
+        clearInterval(pingTimer);
+        pingTimer = null;
+      }
+    };

    const connect = () => {
      if (closed) return;
      ws = new WebSocket(wsUrl);
+
+      ws.onopen = () => {
+        attempt = 0;
+        clearPing();
+        pingTimer = setInterval(() => {
+          if (ws?.readyState === WebSocket.OPEN) {
+            ws.send(JSON.stringify({ event: 'client:ping', data: {} }));
+          }
+        }, 15000);
+      };
+
      ws.onmessage = (ev) => {
        try {
          const payload = JSON.parse(ev.data);
+          if (payload.event === 'client:pong') return;
+          if (payload.event === 'presence:update') {
+            const studentId = Number(payload.data?.studentId ?? 0);
+            if (!studentId) return;
+            presenceHandlers.forEach((h) => h({
+              studentId,
+              online: !!payload.data?.online,
+              classId: Number(payload.data?.classId ?? 0) || undefined,
+            }));
+            return;
+          }
+          if (payload.event === 'teacher:student-violation') {
+            const studentId = Number(payload.data?.studentId ?? 0);
+            if (!studentId) return;
+            playAlertSound();
+            violationHandlers.forEach((h) => h({
+              studentId,
+              studentName: payload.data?.studentName || '',
+              studentCode: payload.data?.studentCode || '',
+              kind: String(payload.data?.kind || ''),
+              reason: String(payload.data?.reason || ''),
+              monitorMode: payload.data?.monitorMode || '',
+              classId: Number(payload.data?.classId ?? 0) || undefined,
+            }));
+            return;
+          }
          if (payload.event !== 'chat:message') return;
          const msg = payload.data as ChatMessage;
          const targetStaff = Number(msg.targetStaffId ?? msg.staffId ?? 0);
          if (targetStaff > 0 && targetStaff !== staffIdRef.current) return;
-          dispatch(msg);
+          dispatchChat(msg);
        } catch {
          /* ignore */
        }
      };
+
      ws.onclose = () => {
+        clearPing();
        if (!closed) {
-          retryTimer = setTimeout(connect, 3000);
+          retryTimer = setTimeout(connect, scheduleBackoff(attempt++));
        }
      };
    };
@@ -59,12 +148,13 @@ export function StaffChatSocket() {

    return () => {
      closed = true;
+      clearPing();
      if (retryTimer) clearTimeout(retryTimer);
      ws?.close();
    };
-  }, [token, staff?.id, dispatch]);
+  }, [token, staff?.id, dispatchChat]);

  return null;
 }

-export { playChatSound };
+export { playChatSound, playAlertSound };
--- a/management/src/index.css
+++ b/management/src/index.css
@@ -3874,6 +3874,15 @@ input:checked + .slider:before {
  color: #93c5fd;
 }

+.chat-toast-alert {
+  background: #7f1d1d;
+  border: 1px solid #f87171;
+}
+
+.chat-toast-alert strong {
+  color: #fecaca;
+}
+
@keyframes chat-toast-in {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
--- a/management/src/utils/notifySound.ts
+++ b/management/src/utils/notifySound.ts
@@ -35,3 +35,29 @@ export function playChatSound() {
  playTone(880, t, 0.12);
  playTone(1174, t + 0.14, 0.14);
 }
+
+/** Louder alert for student violations (quit / kill app) */
+export function playAlertSound() {
+  const ctx = getAudioCtx();
+  if (!ctx) return;
+  if (ctx.state === 'suspended') {
+    void ctx.resume();
+  }
+  const playTone = (freq: number, start: number, duration: number) => {
+    const osc = ctx.createOscillator();
+    const gain = ctx.createGain();
+    osc.type = 'square';
+    osc.frequency.value = freq;
+    gain.gain.setValueAtTime(0.0001, start);
+    gain.gain.exponentialRampToValueAtTime(0.1, start + 0.02);
+    gain.gain.exponentialRampToValueAtTime(0.0001, start + duration);
+    osc.connect(gain);
+    gain.connect(ctx.destination);
+    osc.start(start);
+    osc.stop(start + duration + 0.02);
+  };
+  const t = ctx.currentTime;
+  playTone(520, t, 0.16);
+  playTone(390, t + 0.18, 0.2);
+  playTone(520, t + 0.4, 0.18);
+}
--- a/server/internal/db/db.go
+++ b/server/internal/db/db.go
@@ -53,6 +53,7 @@ func AutoMigrate(db *gorm.DB) error {
 		&models.WifiPoolEntry{},
 		&models.AcceptedWifi{},
 		&models.StudentSession{},
+		&models.StudentViolation{},
 		&models.AttendanceResult{},
 		&models.StaffAccount{},
 		&models.EmailDomain{},
--- a/server/internal/handlers/handlers_learning.go
+++ b/server/internal/handlers/handlers_learning.go
@@ -735,6 +735,227 @@ func ReportBlockedAppHandler(db *gorm.DB) fiber.Handler {
 	}
 }

+// POST /api/student/report-violation — SV tắt app / vi phạm khi đang giám sát
+func ReportViolationHandler(db *gorm.DB) fiber.Handler {
+	return func(c *fiber.Ctx) error {
+		var req struct {
+			StudentRkID int64  `json:"studentRkId"`
+			Kind        string `json:"kind"`
+			Reason      string `json:"reason"`
+			MonitorMode string `json:"monitorMode"`
+			ClientAt    string `json:"clientAt"` // RFC3339 optional
+		}
+		if err := c.BodyParser(&req); err != nil {
+			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "Invalid payload format"})
+		}
+		if req.StudentRkID <= 0 || strings.TrimSpace(req.Kind) == "" {
+			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "studentRkId and kind are required"})
+		}
+
+		kind := strings.ToLower(strings.TrimSpace(req.Kind))
+		reason := strings.TrimSpace(req.Reason)
+		if reason == "" {
+			reason = kind
+		}
+		classID := internalDb.FindActiveClassForStudent(db, req.StudentRkID)
+		clientAt := time.Now()
+		if t, err := time.Parse(time.RFC3339, strings.TrimSpace(req.ClientAt)); err == nil {
+			clientAt = t
+		}
+
+		row := models.StudentViolation{
+			StudentRkID: req.StudentRkID,
+			ClassRkID:   classID,
+			Kind:        kind,
+			Reason:      reason,
+			MonitorMode: strings.TrimSpace(req.MonitorMode),
+			ClientAt:    clientAt,
+		}
+		if err := db.Create(&row).Error; err != nil {
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
+		}
+
+		studentName := ""
+		studentCode := ""
+		var st models.Student
+		if err := db.Where("rk_id = ?", req.StudentRkID).First(&st).Error; err == nil {
+			studentName = st.FullName
+			studentCode = st.StudentCode
+		}
+
+		// Cố ý tắt / crash / môi trường → offline ngay, không dùng grace 8s
+		switch kind {
+		case "app_closed", "unclean_shutdown", "wifi",
+			"guard", "multi_monitor", "user_switch", "session_change", "virtual_desktop":
+			internalWs.Hub.ForceStudentOffline(req.StudentRkID)
+		}
+
+		internalWs.Hub.BroadcastStudentViolation(map[string]any{
+			"id":           row.ID,
+			"studentId":    req.StudentRkID,
+			"studentName":  studentName,
+			"studentCode":  studentCode,
+			"classId":      classID,
+			"kind":         kind,
+			"reason":       reason,
+			"monitorMode":  row.MonitorMode,
+			"clientAt":     clientAt.Format(time.RFC3339),
+			"createdAt":    row.CreatedAt.Format(time.RFC3339),
+		})
+
+		return c.JSON(fiber.Map{"ok": true, "id": row.ID})
+	}
+}
+
+type studentViolationItem struct {
+	ID          uint      `json:"id"`
+	StudentRkID int64     `json:"studentRkId"`
+	StudentCode string    `json:"studentCode"`
+	FullName    string    `json:"fullName"`
+	ClassRkID   int64     `json:"classRkId"`
+	Kind        string    `json:"kind"`
+	Reason      string    `json:"reason"`
+	MonitorMode string    `json:"monitorMode"`
+	ClientAt    time.Time `json:"clientAt"`
+	CreatedAt   time.Time `json:"createdAt"`
+}
+
+// GET /api/classes/:rkId/violations?date=YYYY-MM-DD&kind=
+func ListClassViolationsHandler(db *gorm.DB) fiber.Handler {
+	return func(c *fiber.Ctx) error {
+		classRkID, err := strconv.ParseInt(c.Params("rkId"), 10, 64)
+		if err != nil {
+			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "Invalid class rkId"})
+		}
+		date := c.Query("date")
+		if date == "" {
+			date = time.Now().Format("2006-01-02")
+		}
+		kindFilter := strings.TrimSpace(c.Query("kind", ""))
+
+		var mappings []models.ClassStudent
+		if err := db.Where("class_rk_id = ?", classRkID).Find(&mappings).Error; err != nil {
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
+		}
+		if len(mappings) == 0 {
+			return c.JSON(fiber.Map{"data": []any{}})
+		}
+		studentIDs := make([]int64, 0, len(mappings))
+		for _, m := range mappings {
+			studentIDs = append(studentIDs, m.StudentRkID)
+		}
+
+		var students []models.Student
+		if err := db.Where("rk_id IN ?", studentIDs).Find(&students).Error; err != nil {
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
+		}
+		nameByID := map[int64]models.Student{}
+		for _, st := range students {
+			nameByID[st.RkID] = st
+		}
+
+		dayStart, err := time.ParseInLocation("2006-01-02", date, time.Local)
+		if err != nil {
+			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "Invalid date"})
+		}
+		dayEnd := dayStart.Add(24 * time.Hour)
+
+		q := db.Where("student_rk_id IN ? AND created_at >= ? AND created_at < ?", studentIDs, dayStart, dayEnd)
+		if kindFilter != "" {
+			q = q.Where("kind = ?", kindFilter)
+		}
+		var rows []models.StudentViolation
+		if err := q.Order("created_at desc").Limit(500).Find(&rows).Error; err != nil {
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
+		}
+
+		out := make([]studentViolationItem, 0, len(rows))
+		for _, r := range rows {
+			st := nameByID[r.StudentRkID]
+			out = append(out, studentViolationItem{
+				ID:          r.ID,
+				StudentRkID: r.StudentRkID,
+				StudentCode: st.StudentCode,
+				FullName:    st.FullName,
+				ClassRkID:   r.ClassRkID,
+				Kind:        r.Kind,
+				Reason:      r.Reason,
+				MonitorMode: r.MonitorMode,
+				ClientAt:    r.ClientAt,
+				CreatedAt:   r.CreatedAt,
+			})
+		}
+		return c.JSON(fiber.Map{"data": out, "date": date})
+	}
+}
+
+// GET /api/exam-rooms/:id/violations?date=YYYY-MM-DD
+func ListExamRoomViolationsHandler(db *gorm.DB) fiber.Handler {
+	return func(c *fiber.Ctx) error {
+		id, err := strconv.ParseUint(c.Params("id"), 10, 64)
+		if err != nil {
+			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "Invalid exam room id"})
+		}
+		date := c.Query("date")
+		if date == "" {
+			date = time.Now().Format("2006-01-02")
+		}
+		kindFilter := strings.TrimSpace(c.Query("kind", ""))
+
+		var roster []models.ExamRoomStudent
+		if err := db.Where("exam_room_id = ?", id).Find(&roster).Error; err != nil {
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
+		}
+		if len(roster) == 0 {
+			return c.JSON(fiber.Map{"data": []any{}})
+		}
+		studentIDs := make([]int64, 0, len(roster))
+		for _, s := range roster {
+			studentIDs = append(studentIDs, s.StudentRkID)
+		}
+
+		var students []models.Student
+		_ = db.Where("rk_id IN ?", studentIDs).Find(&students)
+		nameByID := map[int64]models.Student{}
+		for _, st := range students {
+			nameByID[st.RkID] = st
+		}
+
+		dayStart, err := time.ParseInLocation("2006-01-02", date, time.Local)
+		if err != nil {
+			return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "Invalid date"})
+		}
+		dayEnd := dayStart.Add(24 * time.Hour)
+
+		q := db.Where("student_rk_id IN ? AND created_at >= ? AND created_at < ?", studentIDs, dayStart, dayEnd)
+		if kindFilter != "" {
+			q = q.Where("kind = ?", kindFilter)
+		}
+		var rows []models.StudentViolation
+		if err := q.Order("created_at desc").Limit(500).Find(&rows).Error; err != nil {
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
+		}
+
+		out := make([]studentViolationItem, 0, len(rows))
+		for _, r := range rows {
+			st := nameByID[r.StudentRkID]
+			out = append(out, studentViolationItem{
+				ID:          r.ID,
+				StudentRkID: r.StudentRkID,
+				StudentCode: st.StudentCode,
+				FullName:    st.FullName,
+				ClassRkID:   r.ClassRkID,
+				Kind:        r.Kind,
+				Reason:      r.Reason,
+				MonitorMode: r.MonitorMode,
+				ClientAt:    r.ClientAt,
+				CreatedAt:   r.CreatedAt,
+			})
+		}
+		return c.JSON(fiber.Map{"data": out, "date": date})
+	}
+}
+
 // GET /api/app-pool — kho app bị chặn toàn hệ thống (?q= tìm kiếm, limit= mặc định 50)
 func ListAppPoolHandler(db *gorm.DB) fiber.Handler {
 	return func(c *fiber.Ctx) error {
--- a/server/internal/models/models.go
+++ b/server/internal/models/models.go
@@ -179,6 +179,20 @@ type StudentSession struct {

 func (StudentSession) TableName() string { return "student_sessions" }

+// StudentViolation — ghi nhận SV tắt app / vi phạm môi trường khi đang giám sát
+type StudentViolation struct {
+	ID          uint      `gorm:"primaryKey" json:"id"`
+	CreatedAt   time.Time `json:"createdAt"`
+	StudentRkID int64     `gorm:"column:student_rk_id;not null;index" json:"studentRkId"`
+	ClassRkID   int64     `gorm:"column:class_rk_id;index" json:"classRkId"`
+	Kind        string    `gorm:"column:kind;size:64;not null;index" json:"kind"` // app_closed | unclean_shutdown | multi_monitor | user_switch | session_change | virtual_desktop | wifi | guard
+	Reason      string    `gorm:"column:reason;type:text" json:"reason"`
+	MonitorMode string    `gorm:"column:monitor_mode;size:32" json:"monitorMode"`
+	ClientAt    time.Time `gorm:"column:client_at" json:"clientAt"`
+}
+
+func (StudentViolation) TableName() string { return "student_violations" }
+
 // SystemSetting lưu các cấu hình hệ thống động
 type SystemSetting struct {
 	SettingKey   string    `gorm:"primaryKey;column:setting_key;size:128" json:"settingKey"`
--- a/server/internal/websocket/websocket.go
+++ b/server/internal/websocket/websocket.go
@@ -13,8 +13,11 @@ import (
 )

 const (
-	wsPingInterval = 30 * time.Second
-	wsPongWait     = 60 * time.Second
+	// Heartbeat kiểu game: phát hiện mất kết nối trong ~30–45s.
+	wsPingInterval = 15 * time.Second
+	wsPongWait     = 45 * time.Second
+	// Grace khi SV reconnect — tránh nhấp nháy online/offline.
+	studentOfflineGrace = 8 * time.Second
 )

 type SocketMsg struct {
@@ -44,6 +47,10 @@ func (c *SocketClient) WriteRaw(msg []byte) error {
 	return c.Conn.WriteMessage(websocket.TextMessage, msg)
 }

+type offlineGrace struct {
+	until   time.Time
+	classID int64
+}

 type WsHub struct {
 	mu              sync.RWMutex
@@ -51,6 +58,8 @@ type WsHub struct {
 	teachers        map[string]*SocketClient
 	teachersByStaff map[uint][]string // staffId -> teacher connection addresses
 	subscribers     map[int64][]string // studentId -> list of teacher connection addresses
+	grace           map[int64]offlineGrace
+	graceTimers     map[int64]*time.Timer
 }

 var Hub = &WsHub{
@@ -58,13 +67,18 @@ var Hub = &WsHub{
 	teachers:        make(map[string]*SocketClient),
 	teachersByStaff: make(map[uint][]string),
 	subscribers:     make(map[int64][]string),
+	grace:           make(map[int64]offlineGrace),
+	graceTimers:     make(map[int64]*time.Timer),
 }

 func (h *WsHub) IsStudentOnline(studentRkID int64) bool {
 	h.mu.RLock()
 	defer h.mu.RUnlock()
-	_, ok := h.students[studentRkID]
-	return ok
+	if _, ok := h.students[studentRkID]; ok {
+		return true
+	}
+	g, ok := h.grace[studentRkID]
+	return ok && time.Now().Before(g.until)
 }

 func (h *WsHub) PushExamToStudent(studentRkID int64, data map[string]any) {
@@ -102,16 +116,126 @@ func (h *WsHub) PushChatToStaff(staffID uint, data map[string]any) {
 	}
 }

+func (h *WsHub) BroadcastStudentViolation(data map[string]any) {
+	msg := SocketMsg{Event: "teacher:student-violation", Data: data}
+	msgBytes, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	for _, t := range h.teachers {
+		if t != nil {
+			_ = t.WriteRaw(msgBytes)
+		}
+	}
+}
+
+func (h *WsHub) broadcastPresence(studentID int64, online bool, classID int64) {
+	msg := SocketMsg{
+		Event: "presence:update",
+		Data: map[string]any{
+			"studentId": studentID,
+			"online":    online,
+			"classId":   classID,
+		},
+	}
+	msgBytes, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	for _, t := range h.teachers {
+		if t != nil {
+			_ = t.WriteRaw(msgBytes)
+		}
+	}
+}
+
+// ForceStudentOffline — tắt ngay (không chờ grace), dùng khi SV cố ý đóng app / vi phạm.
+func (h *WsHub) ForceStudentOffline(studentID int64) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	classID := int64(0)
+	if client, ok := h.students[studentID]; ok && client != nil {
+		classID = client.ClassID
+		delete(h.students, studentID)
+	}
+	if g, ok := h.grace[studentID]; ok {
+		if classID == 0 {
+			classID = g.classID
+		}
+	}
+	h.cancelGraceLocked(studentID)
+
+	log.Printf("[WS] Student %d force offline (intentional quit/violation)", studentID)
+	h.broadcastPresence(studentID, false, classID)
+	if teachers, exists := h.subscribers[studentID]; exists {
+		for _, tAddr := range teachers {
+			if t, found := h.teachers[tAddr]; found {
+				_ = t.WriteJSON(SocketMsg{
+					Event: "teacher:stream-stopped",
+					Data:  map[string]any{"studentId": studentID},
+				})
+			}
+		}
+	}
+}
+
+func (h *WsHub) cancelGraceLocked(studentID int64) {
+	if t, ok := h.graceTimers[studentID]; ok {
+		t.Stop()
+		delete(h.graceTimers, studentID)
+	}
+	delete(h.grace, studentID)
+}
+
+func (h *WsHub) finalizeStudentOffline(studentID int64, classID int64) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	if _, online := h.students[studentID]; online {
+		return
+	}
+	if _, ok := h.grace[studentID]; !ok {
+		return
+	}
+	delete(h.grace, studentID)
+	delete(h.graceTimers, studentID)
+
+	log.Printf("[WS] Student %d offline after grace", studentID)
+	h.broadcastPresence(studentID, false, classID)
+
+	if teachers, exists := h.subscribers[studentID]; exists {
+		for _, tAddr := range teachers {
+			if t, found := h.teachers[tAddr]; found {
+				_ = t.WriteJSON(SocketMsg{
+					Event: "teacher:stream-stopped",
+					Data:  map[string]any{"studentId": studentID},
+				})
+			}
+		}
+	}
+}
+
 func (h *WsHub) GetOnlineStudentIDs(classID int64) []int64 {
 	h.mu.RLock()
 	defer h.mu.RUnlock()

+	seen := map[int64]bool{}
 	var ids []int64
+	now := time.Now()
 	for _, client := range h.students {
 		if client.ClassID == classID {
+			seen[client.StudentID] = true
 			ids = append(ids, client.StudentID)
 		}
 	}
+	for sid, g := range h.grace {
+		if now.Before(g.until) && g.classID == classID && !seen[sid] {
+			ids = append(ids, sid)
+		}
+	}
 	if ids == nil {
 		return []int64{}
 	}
@@ -124,8 +248,14 @@ func (h *WsHub) Register(c *SocketClient) {

 	c.Addr = c.Conn.RemoteAddr().String()
 	if c.Role == "student" {
+		wasInGrace := false
+		if _, ok := h.grace[c.StudentID]; ok {
+			wasInGrace = true
+		}
+		h.cancelGraceLocked(c.StudentID)
 		h.students[c.StudentID] = c
-		log.Printf("[WS] Student %d registered (Address: %s, Class: %d)", c.StudentID, c.Addr, c.ClassID)
+		log.Printf("[WS] Student %d registered (Address: %s, Class: %d, reconnectGrace=%v)", c.StudentID, c.Addr, c.ClassID, wasInGrace)
+		h.broadcastPresence(c.StudentID, true, c.ClassID)
 		if subs, exists := h.subscribers[c.StudentID]; exists && len(subs) > 0 {
 			_ = c.WriteJSON(SocketMsg{Event: "start_screenshot_stream"})
 			_ = c.WriteJSON(SocketMsg{Event: "start_webcam_stream"})
@@ -151,19 +281,17 @@ func (h *WsHub) Unregister(c *SocketClient) {
 			return
 		}
 		delete(h.students, c.StudentID)
-		log.Printf("[WS] Student %d disconnected", c.StudentID)
+		classID := c.ClassID
+		studentID := c.StudentID

-		// Báo cho các giáo viên đang xem là stream của học sinh đã dừng
-		if teachers, exists := h.subscribers[c.StudentID]; exists {
-			for _, tAddr := range teachers {
-				if t, found := h.teachers[tAddr]; found {
-					_ = t.WriteJSON(SocketMsg{
-						Event: "teacher:stream-stopped",
-						Data:  map[string]any{"studentId": c.StudentID},
+		h.cancelGraceLocked(studentID)
+		deadline := time.Now().Add(studentOfflineGrace)
+		h.grace[studentID] = offlineGrace{until: deadline, classID: classID}
+		h.graceTimers[studentID] = time.AfterFunc(studentOfflineGrace, func() {
+			h.finalizeStudentOffline(studentID, classID)
 		})
-				}
-			}
-		}
+		log.Printf("[WS] Student %d disconnected — grace %v before offline", studentID, studentOfflineGrace)
+		// Chưa broadcast offline / stream-stopped — chờ grace (reconnect nhanh như game).
 	} else if c.Role == "teacher" {
 		delete(h.teachers, c.Addr)
 		if c.StaffID > 0 {
@@ -182,7 +310,6 @@ func (h *WsHub) Unregister(c *SocketClient) {
 		}
 		log.Printf("[WS] Teacher %s disconnected", c.Addr)

-		// Dọn dẹp subscriptions của giáo viên này
 		for sID, teachersList := range h.subscribers {
 			newList := []string{}
 			for _, addr := range teachersList {
@@ -192,7 +319,6 @@ func (h *WsHub) Unregister(c *SocketClient) {
 			}
 			if len(newList) == 0 {
 				delete(h.subscribers, sID)
-				// Nếu không còn ai xem học sinh này, gửi lệnh tắt camera/screen cho client học sinh
 				if student, exists := h.students[sID]; exists {
 					_ = student.WriteJSON(SocketMsg{Event: "stop_screenshot_stream"})
 					_ = student.WriteJSON(SocketMsg{Event: "stop_webcam_stream"})
@@ -204,12 +330,10 @@ func (h *WsHub) Unregister(c *SocketClient) {
 	}
 }

-// Teacher bắt đầu xem stream của Student
 func (h *WsHub) Subscribe(teacherAddr string, studentID int64) {
 	h.mu.Lock()
 	defer h.mu.Unlock()

-	// Thêm giáo viên vào list người xem của học sinh
 	teachersList := h.subscribers[studentID]
 	alreadySubscribed := false
 	for _, addr := range teachersList {
@@ -223,14 +347,12 @@ func (h *WsHub) Subscribe(teacherAddr string, studentID int64) {
 		log.Printf("[WS] Teacher %s subscribed to student %d stream", teacherAddr, studentID)
 	}

-	// Phát lệnh cho máy học sinh bật stream (nếu học sinh đang online)
 	if student, exists := h.students[studentID]; exists {
 		_ = student.WriteJSON(SocketMsg{Event: "start_screenshot_stream"})
 		_ = student.WriteJSON(SocketMsg{Event: "start_webcam_stream"})
 	}
 }

-// Teacher dừng xem stream của Student
 func (h *WsHub) Unsubscribe(teacherAddr string, studentID int64) {
 	h.mu.Lock()
 	defer h.mu.Unlock()
@@ -250,8 +372,6 @@ func (h *WsHub) Unsubscribe(teacherAddr string, studentID int64) {
 	if len(newList) == 0 {
 		delete(h.subscribers, studentID)
 		log.Printf("[WS] Student %d has no more proctor subscribers. Stopping streams.", studentID)
-
-		// Báo học sinh tắt camera & screen stream để tiết kiệm mạng và CPU
 		if student, exists := h.students[studentID]; exists {
 			_ = student.WriteJSON(SocketMsg{Event: "stop_screenshot_stream"})
 			_ = student.WriteJSON(SocketMsg{Event: "stop_webcam_stream"})
@@ -261,7 +381,6 @@ func (h *WsHub) Unsubscribe(teacherAddr string, studentID int64) {
 	}
 }

-// Chuyển tiếp frame ảnh từ Student đến các Teacher đã subscribe
 func (h *WsHub) RelayFrame(studentID int64, event string, data map[string]any) {
 	h.mu.RLock()
 	teachersList, exists := h.subscribers[studentID]
@@ -269,7 +388,6 @@ func (h *WsHub) RelayFrame(studentID int64, event string, data map[string]any) {
 		h.mu.RUnlock()
 		return
 	}
-	// Snapshot subscriber addresses while holding read lock
 	addrs := make([]string, len(teachersList))
 	copy(addrs, teachersList)
 	h.mu.RUnlock()
@@ -291,18 +409,30 @@ func (h *WsHub) RelayFrame(studentID int64, event string, data map[string]any) {
 		return
 	}

+	var dead []string
 	h.mu.RLock()
-	defer h.mu.RUnlock()
 	for _, addr := range addrs {
 		if t, found := h.teachers[addr]; found {
 			if err := t.WriteRaw(msgBytes); err != nil {
 				log.Printf("[WS] Relay to teacher %s failed: %v", addr, err)
+				dead = append(dead, addr)
 			}
 		}
 	}
+	h.mu.RUnlock()
+
+	for _, addr := range dead {
+		if t, ok := func() (*SocketClient, bool) {
+			h.mu.RLock()
+			defer h.mu.RUnlock()
+			t, ok := h.teachers[addr]
+			return t, ok
+		}(); ok && t != nil {
+			_ = t.Conn.Close()
+		}
+	}
 }

-// WebSocket handler cho Fiber route
 func WebSocketHandler(db *gorm.DB) func(*websocket.Conn) {
 	return func(c *websocket.Conn) {
 		role := c.Query("role", "student")
@@ -351,7 +481,7 @@ func WebSocketHandler(db *gorm.DB) func(*websocket.Conn) {
 					return
 				case <-ticker.C:
 					client.writeMu.Lock()
-					err := c.WriteMessage(websocket.PingMessage, nil)
+					err := c.WriteControl(websocket.PingMessage, []byte("ping"), time.Now().Add(5*time.Second))
 					client.writeMu.Unlock()
 					if err != nil {
 						return
@@ -372,14 +502,14 @@ func WebSocketHandler(db *gorm.DB) func(*websocket.Conn) {
 				continue
 			}

-			// Xử lý các sự kiện
 			switch msg.Event {
+			case "client:ping":
+				_ = client.WriteJSON(SocketMsg{Event: "client:pong", Data: map[string]any{"t": time.Now().UnixMilli()}})
+
 			case "screenshot_stream_frame", "webcam_stream_frame":
-				// Nhận frame từ học sinh, chuyển tiếp về các thầy cô
 				Hub.RelayFrame(client.StudentID, msg.Event, msg.Data)

 			case "teacher:subscribe":
-				// Giáo viên đăng ký xem học sinh cụ thể
 				if client.Role == "teacher" {
 					if sIDVal, ok := msg.Data["studentId"]; ok {
 						var sID int64
@@ -396,7 +526,6 @@ func WebSocketHandler(db *gorm.DB) func(*websocket.Conn) {
 				}

 			case "teacher:unsubscribe":
-				// Giáo viên hủy đăng ký
 				if client.Role == "teacher" {
 					if sIDVal, ok := msg.Data["studentId"]; ok {
 						var sID int64
--- a/server/main.go
+++ b/server/main.go
@@ -93,6 +93,7 @@ func main() {
 	api.Get("/student/wifi-policy", handlers.GetStudentWifiPolicyHandler(gormDB))
 	api.Post("/student/report-wifi", handlers.ReportWifiHandler(gormDB))
 	api.Post("/student/report-blocked-app", handlers.ReportBlockedAppHandler(gormDB))
+	api.Post("/student/report-violation", handlers.ReportViolationHandler(gormDB))
 	api.Get("/student/chat/messages", handlers.StudentListChatHandler(gormDB))
 	api.Post("/student/chat/messages", handlers.StudentSendChatHandler(gormDB))
 	api.Get("/student/chat/conversations", handlers.StudentListChatConversationsHandler(gormDB))
@@ -156,6 +157,7 @@ func main() {
 	staff.Post("/network/accepted-wifis/add", handlers.AddAcceptedWifiHandler(gormDB))
 	staff.Delete("/network/accepted-wifis/:id", handlers.DeleteAcceptedWifiHandler(gormDB))
 	staff.Get("/classes/:rkId/session-logs", handlers.ListClassSessionLogsHandler(gormDB))
+	staff.Get("/classes/:rkId/violations", handlers.ListClassViolationsHandler(gormDB))
 	staff.Get("/classes/:rkId/online-students", handlers.GetOnlineStudentsHandler(gormDB))
 	staff.Get("/classes/:rkId/schedule-conflicts", handlers.GetClassScheduleConflictsHandler(gormDB))

@@ -187,6 +189,7 @@ func main() {
 	staff.Get("/exam-rooms/search-students", handlers.SearchExamStudentsHandler(gormDB))
 	staff.Get("/exam-rooms/:id", handlers.GetExamRoomHandler(gormDB))
 	staff.Get("/exam-rooms/:id/online-students", handlers.GetExamRoomOnlineStudentsHandler(gormDB))
+	staff.Get("/exam-rooms/:id/violations", handlers.ListExamRoomViolationsHandler(gormDB))
 	staff.Patch("/exam-rooms/:id", handlers.UpdateExamRoomHandler(gormDB))
 	staff.Delete("/exam-rooms/:id", handlers.DeleteExamRoomHandler(gormDB))
 	staff.Post("/exam-rooms/:id/students", handlers.AddExamRoomStudentsHandler(gormDB))