dashboard(alarms): provider-status badge (alarmmgr vs degraded subtag)

src/ZB.MOM.WW.MxGateway.Server/Dashboard/Components/Pages/AlarmsPage.razor

@@ -1,7 +1,10 @@
 @page "/alarms"
 @implements IAsyncDisposable
+@using Microsoft.AspNetCore.SignalR.Client
+@using ZB.MOM.WW.MxGateway.Server.Dashboard.Hubs
 @inject IDashboardLiveDataService LiveData
 @inject IOptions<GatewayOptions> GatewayOptions
+@inject DashboardHubConnectionFactory HubFactory
 
 <PageTitle>Dashboard Alarms</PageTitle>
 
@@ -10,6 +13,12 @@
         <h1>Alarms</h1>
         <div class="text-secondary">@HeaderLine()</div>
     </div>
+    <div class="d-flex align-items-center gap-2">
+        <span class="badge @_providerStatus.BadgeCssClass"
+              title="@ProviderStatusTitle()">
+            @_providerStatus.Label
+        </span>
+    </div>
 </div>
 
 @if (!GatewayOptions.Value.Alarms.Enabled)
@@ -163,10 +172,44 @@
     private readonly CancellationTokenSource _cts = new();
     private Task? _pollTask;
 
+    private DashboardAlarmProviderStatus _providerStatus = DashboardAlarmProviderStatus.Healthy;
+    private HubConnection? _alarmsHub;
+
     /// <inheritdoc />
     protected override void OnInitialized()
     {
         _pollTask = PollLoopAsync();
+        _ = AttachAlarmsHubAsync();
+    }
+
+    private string? ProviderStatusTitle()
+    {
+        return _providerStatus.IsDegraded && !string.IsNullOrWhiteSpace(_providerStatus.Reason)
+            ? _providerStatus.Reason
+            : null;
+    }
+
+    private async Task AttachAlarmsHubAsync()
+    {
+        _alarmsHub = HubFactory.Create("/hubs/alarms");
+        _alarmsHub.On<AlarmFeedMessage>(AlarmsHub.AlarmMessage, async message =>
+        {
+            if (message.PayloadCase == AlarmFeedMessage.PayloadOneofCase.ProviderStatus)
+            {
+                _providerStatus = DashboardAlarmProviderStatus.FromFeed(message);
+                await InvokeAsync(StateHasChanged).ConfigureAwait(false);
+            }
+        });
+
+        try
+        {
+            await _alarmsHub.StartAsync(_cts.Token).ConfigureAwait(false);
+        }
+        catch
+        {
+            // The badge is best-effort; it stays at the healthy default until
+            // the hub reconnects and delivers a fresh provider-status message.
+        }
     }
 
     private string HeaderLine()
@@ -268,6 +311,19 @@
     public async ValueTask DisposeAsync()
     {
         await _cts.CancelAsync();
+
+        if (_alarmsHub is not null)
+        {
+            try
+            {
+                await _alarmsHub.DisposeAsync();
+            }
+            catch
+            {
+                // Disposal-time errors are best-effort.
+            }
+        }
+
         if (_pollTask is not null)
         {
             try