backend/src/main/java/com/petshop/backend/controller/RefundController.java

@@ -30,7 +30,7 @@ public class RefundController {
     }
 
     @PostMapping
-    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF')")
     public ResponseEntity<RefundResponse> createRefund(@Valid @RequestBody RefundRequest request) {
         Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
         String role = authentication.getAuthorities().stream()
@@ -85,7 +85,7 @@ public class RefundController {
     }
 
     @PutMapping("/{id}")
-    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    @PreAuthorize("hasRole('STAFF')")
     public ResponseEntity<RefundResponse> updateRefund(@PathVariable Long id, @Valid @RequestBody RefundUpdateRequest request) {
         return ResponseEntity.ok(refundService.updateRefundStatus(id, request.getStatus()));
     }

backend/src/main/java/com/petshop/backend/controller/SaleController.java

@@ -40,7 +40,7 @@ public class SaleController {
     }
 
     @PostMapping
-    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    @PreAuthorize("hasRole('STAFF')")
     public ResponseEntity<SaleResponse> createSale(@Valid @RequestBody SaleRequest request) {
         return ResponseEntity.status(HttpStatus.CREATED).body(saleService.createSale(request));
     }

backend/src/main/java/com/petshop/backend/exception/GlobalExceptionHandler.java

@@ -42,9 +42,10 @@ public class GlobalExceptionHandler {
             errors.put(fieldName, errorMessage);
         });
 
+        String firstMessage = errors.values().stream().findFirst().orElse("Validation failed");
         Map<String, Object> response = new HashMap<>();
         response.put("status", HttpStatus.BAD_REQUEST.value());
-        response.put("message", "Validation failed");
+        response.put("message", firstMessage);
         response.put("errors", errors);
         response.put("details", buildDetails(ex));
         response.put("path", request.getRequestURI());

backend/src/main/java/com/petshop/backend/repository/ProductRepository.java

@@ -11,6 +11,10 @@ import org.springframework.stereotype.Repository;
 @Repository
 public interface ProductRepository extends JpaRepository<Product, Long> {
 
+    boolean existsByProdNameIgnoreCase(String prodName);
+
+    boolean existsByProdNameIgnoreCaseAndProdIdNot(String prodName, Long prodId);
+
     @Query("SELECT p FROM Product p WHERE " +
            "(:q IS NULL OR LOWER(p.prodName) LIKE LOWER(CONCAT('%', :q, '%')) OR LOWER(COALESCE(p.prodDesc, '')) LIKE LOWER(CONCAT('%', :q, '%'))) AND " +
            "(:categoryId IS NULL OR p.category.categoryId = :categoryId)")

backend/src/main/java/com/petshop/backend/service/ProductService.java

@@ -5,6 +5,7 @@ import com.petshop.backend.dto.product.ProductRequest;
 import com.petshop.backend.dto.product.ProductResponse;
 import com.petshop.backend.entity.Category;
 import com.petshop.backend.entity.Product;
+import com.petshop.backend.exception.BusinessException;
 import com.petshop.backend.exception.ResourceNotFoundException;
 import com.petshop.backend.repository.CategoryRepository;
 import com.petshop.backend.repository.ProductRepository;
@@ -45,6 +46,10 @@ public class ProductService {
 
     @Transactional
     public ProductResponse createProduct(ProductRequest request) {
+        if (productRepository.existsByProdNameIgnoreCase(request.getProdName())) {
+            throw new BusinessException("A product with this name already exists");
+        }
+
         Category category = categoryRepository.findById(request.getCategoryId())
                 .orElseThrow(() -> new ResourceNotFoundException("Category not found with id: " + request.getCategoryId()));
 
@@ -63,6 +68,10 @@ public class ProductService {
         Product product = productRepository.findById(id)
                 .orElseThrow(() -> new ResourceNotFoundException("Product not found with id: " + id));
 
+        if (productRepository.existsByProdNameIgnoreCaseAndProdIdNot(request.getProdName(), id)) {
+            throw new BusinessException("A product with this name already exists");
+        }
+
         Category category = categoryRepository.findById(request.getCategoryId())
                 .orElseThrow(() -> new ResourceNotFoundException("Category not found with id: " + request.getCategoryId()));
 

backend/src/main/resources/application.yml

@@ -68,6 +68,8 @@ openrouter:
   model: ${OPENROUTER_MODEL:openrouter/free}
 
 logging:
+  file:
+    name: ${LOG_FILE:log.txt}
   level:
     com.petshop: ${LOG_LEVEL:INFO}
     org.springframework.security: ${LOG_LEVEL_SECURITY:WARN}

desktop/src/main/java/org/example/petshopdesktop/PetShopApplication.java

@@ -5,6 +5,7 @@ import javafx.fxml.FXMLLoader;
 import javafx.scene.Scene;
 import javafx.scene.image.Image;
 import javafx.stage.Stage;
+import org.example.petshopdesktop.util.DesktopNotificationService;
 
 import java.io.IOException;
 import java.util.Objects;
@@ -26,5 +27,9 @@ public class PetShopApplication extends Application {
 
         stage.setScene(scene);
         stage.show();
+
+        DesktopNotificationService.getInstance().init(
+                stage.getIcons().isEmpty() ? null : stage.getIcons().get(0)
+        );
     }
 }

desktop/src/main/java/org/example/petshopdesktop/api/ChatRealtimeClient.java

@@ -4,6 +4,7 @@ import org.example.petshopdesktop.api.dto.chat.ConversationResponse;
 import org.example.petshopdesktop.api.dto.chat.MessageRequest;
 import org.example.petshopdesktop.api.dto.chat.MessageResponse;
 import org.example.petshopdesktop.auth.UserSession;
+import org.example.petshopdesktop.util.DesktopNotificationService;
 
 import java.net.URI;
 import java.net.http.HttpClient;
@@ -72,6 +73,16 @@ public class ChatRealtimeClient implements WebSocket.Listener {
         updateNotificationState();
     }
 
+    public void markConversationReplied(Long conversationId, Long senderId) {
+        synchronized (lock) {
+            ConversationResponse conv = globalConversations.get(conversationId);
+            if (conv != null) {
+                conv.setLastSenderId(senderId);
+            }
+        }
+        updateNotificationState();
+    }
+
     public boolean hasActionableChats() {
         synchronized (lock) {
             UserSession session = UserSession.getInstance();
@@ -333,7 +344,13 @@ public class ChatRealtimeClient implements WebSocket.Listener {
                     if (messageListener != null) {
                         messageListener.accept(message);
                     }
-                    
+
+                    Long currentUserId = UserSession.getInstance().getUserId();
+                    if (message.getSenderId() != null && !message.getSenderId().equals(currentUserId)) {
+                        DesktopNotificationService.getInstance()
+                                .notifyNewMessage(message.getSenderDisplayName(), message.getContent());
+                    }
+
                     // Also update globalConversation last sender if this is the active conversation
                     synchronized (lock) {
                         ConversationResponse conv = globalConversations.get(message.getConversationId());

desktop/src/main/java/org/example/petshopdesktop/controllers/ChatController.java

@@ -196,6 +196,7 @@ public class ChatController {
                 MessageResponse response = ChatApi.getInstance().sendMessage(convId, request);
                 Platform.runLater(() -> {
                     btnSend.setDisable(false);
+                    realtimeClient.markConversationReplied(convId, UserSession.getInstance().getUserId());
                     appendMessageIfSelected(response);
                     if (selectedAttachmentFile != null) {
                         clearLocalAttachment();
@@ -380,6 +381,7 @@ public class ChatController {
                 List<ConversationResponse> response = ChatApi.getInstance().listConversations();
                 response.sort(Comparator.comparing(ChatController::conversationSortTime, Comparator.nullsLast(Comparator.reverseOrder())));
                 Platform.runLater(() -> {
+                    realtimeClient.initializeState(response);
                     conversations.setAll(response);
                     refreshSections();
                     restoreSelection();
@@ -471,6 +473,7 @@ public class ChatController {
                 .findFirst()
                 .ifPresent(conversation -> {
                     conversation.setLastMessage(message.getContent());
+                    conversation.setLastSenderId(message.getSenderId());
                     conversation.setUpdatedAt(message.getTimestamp());
                     conversations.sort(Comparator.comparing(ChatController::conversationSortTime, Comparator.nullsLast(Comparator.reverseOrder())));
                     refreshSections();

desktop/src/main/java/org/example/petshopdesktop/util/DesktopNotificationService.java

@@ -0,0 +1,63 @@
+package org.example.petshopdesktop.util;
+
+import javafx.embed.swing.SwingFXUtils;
+import javafx.scene.image.Image;
+
+import java.awt.SystemTray;
+import java.awt.Toolkit;
+import java.awt.TrayIcon;
+import java.awt.image.BufferedImage;
+
+public class DesktopNotificationService {
+    private static final DesktopNotificationService INSTANCE = new DesktopNotificationService();
+
+    private TrayIcon trayIcon;
+    private boolean trayInitialized = false;
+
+    private DesktopNotificationService() {}
+
+    public static DesktopNotificationService getInstance() {
+        return INSTANCE;
+    }
+
+    public void init(Image appIcon) {
+        if (!SystemTray.isSupported()) return;
+        try {
+            BufferedImage image;
+            if (appIcon != null) {
+                image = SwingFXUtils.fromFXImage(appIcon, null);
+            } else {
+                image = new BufferedImage(16, 16, BufferedImage.TYPE_INT_ARGB);
+            }
+            trayIcon = new TrayIcon(image, "Leon's Pet Store");
+            trayIcon.setImageAutoSize(true);
+            SystemTray.getSystemTray().add(trayIcon);
+            trayInitialized = true;
+        } catch (Exception ignored) {}
+    }
+
+    public void notifyNewMessage(String senderName, String content) {
+        Thread t = new Thread(() -> {
+            Toolkit.getDefaultToolkit().beep();
+            showNotification(senderName, content);
+        });
+        t.setDaemon(true);
+        t.start();
+    }
+
+    private void showNotification(String senderName, String content) {
+        String title = senderName != null ? senderName : "New Message";
+        String body = content != null
+                ? (content.length() > 100 ? content.substring(0, 100) + "..." : content)
+                : "Attachment";
+
+        if (trayInitialized && trayIcon != null) {
+            trayIcon.displayMessage(title, body, TrayIcon.MessageType.INFO);
+            return;
+        }
+
+        try {
+            new ProcessBuilder("notify-send", title, body).start();
+        } catch (Exception ignored) {}
+    }
+}