feat(notification): 新增全部标记已读接口

internal/service/notification.go

@@ -108,6 +108,26 @@ func (s *NotificationService) Read(ctx context.Context, userID int64, request *d
 	return &dto.NotificationUnreadResponse{UnreadCount: cnt}, nil
 }
 
+// ReadAll 将当前用户全部未读通知标记为已读，并回填未读数缓存。
+// 与单条已读一致：以 MySQL 为权威重新统计后返回，避免 Redis 计数偏差。
+func (s *NotificationService) ReadAll(ctx context.Context, userID int64) (*dto.NotificationUnreadResponse, *errcode.Error) {
+	ctx, span := global.Tracer.Start(ctx, "svc.NotificationReadAll")
+	defer span.End()
+
+	affected, err := s.notificationDao.NotificationUpdateReadAllByUserID(ctx, userID)
+	if err != nil {
+		slog.ErrorContext(ctx, "mark all notifications read failed", "user_id", userID, "error", err)
+		return nil, errcode.DatabaseError
+	}
+	slog.InfoContext(ctx, "mark all notifications read", "user_id", userID, "affected", affected)
+
+	cnt, cerr := s.unreadCount(ctx, userID)
+	if cerr != nil {
+		return nil, cerr
+	}
+	return &dto.NotificationUnreadResponse{UnreadCount: cnt}, nil
+}
+
 // Unread 获取当前用户未读数（以 MySQL 为权威）。
 func (s *NotificationService) Unread(ctx context.Context, userID int64) (*dto.NotificationUnreadResponse, *errcode.Error) {
 	ctx, span := global.Tracer.Start(ctx, "svc.NotificationUnread")