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backend/F9WebAiTest.Api/Services/BusinessChangedEventHandler.cs

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+using F9WebAiTest.Api.Hubs;
+using F9WebAiTest.Application.Services;
+using MediatR;
+using Microsoft.AspNetCore.SignalR;
+
+namespace F9WebAiTest.Api.Services;
+
+/// <summary>
+/// 业务状态变更事件的 SignalR 推送处理器。
+/// 业务服务发布 BusinessChangedEvent 后，推送给所有在线客户端，
+/// 各端监听 "BusinessChanged" 后刷新已打开的相关页面，实现多端实时同步。
+/// </summary>
+public class BusinessChangedEventHandler : INotificationHandler<BusinessChangedEvent>
+{
+    private readonly IHubContext<NotificationHub> _hubContext;
+
+    public BusinessChangedEventHandler(IHubContext<NotificationHub> hubContext)
+        => _hubContext = hubContext;
+
+    public Task Handle(BusinessChangedEvent e, CancellationToken ct)
+        => _hubContext.Clients.All.SendAsync("BusinessChanged", e, ct);
+}