完善契约与客户端、服务端的收发代码

SHH.CameraDashboard/Services/ServerStateManager.cs

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+using System.Collections.ObjectModel;
+using System.Windows; // 如果是 WPF
+using SHH.Contracts;
+
+namespace SHH.CameraDashboard
+{
+    /// <summary>
+    /// 服务端状态管理器
+    /// <para>职责：维护在线设备列表，供 UI 绑定</para>
+    /// </summary>
+    public class ServerStateManager
+    {
+        // UI 绑定的集合
+        public ObservableCollection<ServerNodeInfo> OnlineServers { get; }
+            = new ObservableCollection<ServerNodeInfo>();
+
+        /// <summary>
+        /// 处理注册/心跳包，更新列表
+        /// </summary>
+        public void RegisterOrUpdate(ServerRegistrationDto info)
+        {
+            // 确保在 UI 线程执行 (WPF 必须)
+            Application.Current.Dispatcher.Invoke(() =>
+            {
+                var existing = OnlineServers.FirstOrDefault(x => x.InstanceId == info.InstanceId);
+
+                if (existing != null)
+                {
+                    // 更新已有节点状态
+                    existing.IpAddress = info.ServerIp;
+                    existing.WebApiPort = info.WebApiPort;
+                    existing.LastHeartbeat = DateTime.Now;
+                    existing.Status = "在线";
+                    // 触发属性变更通知...
+                }
+                else
+                {
+                    // 新增节点
+                    OnlineServers.Add(new ServerNodeInfo
+                    {
+                        InstanceId = info.InstanceId,
+                        IpAddress = info.ServerIp,
+                        WebApiPort = info.WebApiPort,
+                        ProcessId = info.ProcessId,
+                        LastHeartbeat = DateTime.Now,
+                        Status = "在线"
+                    });
+                }
+            });
+        }
+    }
+
+    /// <summary>
+    /// UI 显示用的模型
+    /// </summary>
+    public class ServerNodeInfo
+    {
+        public string InstanceId { get; set; }
+        public string IpAddress { get; set; }
+        public int WebApiPort { get; set; }
+        public int ProcessId { get; set; }
+        public string Status { get; set; }
+        public DateTime LastHeartbeat { get; set; }
+
+        // 方便 UI 显示的字符串
+        public string DisplayName => $"{InstanceId} ({IpAddress}:{WebApiPort})";
+    }
+}