feat(notification-outbox): add outbox KPI tiles to Health dashboard

src/ScadaLink.CentralUI/Components/Pages/Monitoring/Health.razor

@@ -4,9 +4,12 @@
 @using ScadaLink.Commons.Entities.Sites
 @using ScadaLink.Commons.Interfaces.Repositories
 @using ScadaLink.HealthMonitoring
+@using ScadaLink.Commons.Messages.Notification
+@using ScadaLink.Communication
 @implements IDisposable
 @inject ICentralHealthAggregator HealthAggregator
 @inject ISiteRepository SiteRepository
+@inject CommunicationService CommunicationService
 
 <div class="container-fluid mt-3">
     <div class="d-flex justify-content-between align-items-center mb-3">
@@ -17,6 +20,39 @@
         </div>
     </div>
 
+    @* Notification Outbox headline KPIs — a central concern, shown regardless of site reports *@
+    <h6 class="text-muted mb-2">Notification Outbox</h6>
+    <div class="row g-3 mb-3">
+        <div class="col-lg-4 col-md-6 col-12">
+            <div class="card h-100">
+                <div class="card-body text-center">
+                    <h3 class="mb-0">@OutboxTileValue(_outboxKpi.QueueDepth)</h3>
+                    <small class="text-muted">Queue Depth</small>
+                </div>
+            </div>
+        </div>
+        <div class="col-lg-4 col-md-6 col-12">
+            <div class="card h-100 @(_outboxKpiAvailable && _outboxKpi.StuckCount > 0 ? "border-warning" : "")">
+                <div class="card-body text-center">
+                    <h3 class="mb-0 @(_outboxKpiAvailable && _outboxKpi.StuckCount > 0 ? "text-warning" : "")">@OutboxTileValue(_outboxKpi.StuckCount)</h3>
+                    <small class="text-muted">Stuck</small>
+                </div>
+            </div>
+        </div>
+        <div class="col-lg-4 col-md-6 col-12">
+            <div class="card h-100 @(_outboxKpiAvailable && _outboxKpi.ParkedCount > 0 ? "border-danger" : "")">
+                <div class="card-body text-center">
+                    <h3 class="mb-0 @(_outboxKpiAvailable && _outboxKpi.ParkedCount > 0 ? "text-danger" : "")">@OutboxTileValue(_outboxKpi.ParkedCount)</h3>
+                    <small class="text-muted">Parked</small>
+                </div>
+            </div>
+        </div>
+    </div>
+    @if (!_outboxKpiAvailable && _outboxKpiError != null)
+    {
+        <div class="text-muted small mb-3">Notification Outbox KPIs unavailable: @_outboxKpiError</div>
+    }
+
     @if (_siteStates.Count == 0)
     {
         <div class="alert alert-info">No site health reports received yet.</div>
@@ -294,6 +330,12 @@
     private Timer? _refreshTimer;
     private int _autoRefreshSeconds = 10;
 
+    // Notification Outbox headline KPIs, refreshed alongside the site states.
+    private NotificationKpiResponse _outboxKpi =
+        new(string.Empty, true, null, 0, 0, 0, 0, null);
+    private bool _outboxKpiAvailable;
+    private string? _outboxKpiError;
+
     private static bool SiteHasActiveErrors(SiteHealthState state)
     {
         var report = state.LatestReport;
@@ -316,22 +358,53 @@
             // Non-fatal — fall back to showing siteId only
         }
 
-        RefreshNow();
+        await RefreshNow();
         _refreshTimer = new Timer(_ =>
         {
-            InvokeAsync(() =>
+            InvokeAsync(async () =>
             {
-                RefreshNow();
+                await RefreshNow();
                 StateHasChanged();
             });
         }, null, TimeSpan.FromSeconds(_autoRefreshSeconds), TimeSpan.FromSeconds(_autoRefreshSeconds));
     }
 
-    private void RefreshNow()
+    private async Task RefreshNow()
     {
         _siteStates = HealthAggregator.GetAllSiteStates();
+        await LoadOutboxKpis();
     }
 
+    private async Task LoadOutboxKpis()
+    {
+        try
+        {
+            var response = await CommunicationService.GetNotificationKpisAsync(
+                new NotificationKpiRequest(Guid.NewGuid().ToString("N")));
+            if (response.Success)
+            {
+                _outboxKpi = response;
+                _outboxKpiAvailable = true;
+                _outboxKpiError = null;
+            }
+            else
+            {
+                _outboxKpiAvailable = false;
+                _outboxKpiError = response.ErrorMessage ?? "KPI query failed.";
+            }
+        }
+        catch (Exception ex)
+        {
+            _outboxKpiAvailable = false;
+            _outboxKpiError = $"KPI query failed: {ex.Message}";
+        }
+    }
+
+    // Tiles show the numeric KPI when available, or an em dash when the outbox
+    // KPI query failed — matching how the page renders other unavailable data.
+    private string OutboxTileValue(int value) =>
+        _outboxKpiAvailable ? value.ToString() : "—";
+
     private string GetSiteName(string siteId)
     {
         return _siteNames.GetValueOrDefault(siteId, siteId);

tests/ScadaLink.CentralUI.Tests/Pages/HealthPageTests.cs

@@ -0,0 +1,124 @@
+using System.Security.Claims;
+using Akka.Actor;
+using Bunit;
+using Microsoft.AspNetCore.Components.Authorization;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using NSubstitute;
+using ScadaLink.Commons.Entities.Sites;
+using ScadaLink.Commons.Interfaces.Repositories;
+using ScadaLink.Commons.Messages.Notification;
+using ScadaLink.Communication;
+using ScadaLink.HealthMonitoring;
+using HealthPage = ScadaLink.CentralUI.Components.Pages.Monitoring.Health;
+
+namespace ScadaLink.CentralUI.Tests.Pages;
+
+/// <summary>
+/// bUnit rendering tests for the Health Monitoring dashboard (Task 24).
+///
+/// Scope: the Notification Outbox KPI tile row added to the Health dashboard.
+/// <see cref="ICentralHealthAggregator"/> is an interface (mockable), but
+/// <see cref="CommunicationService"/> is a concrete class whose outbox calls
+/// route through an injected notification-outbox <see cref="IActorRef"/>; the
+/// tests reuse the scripted-actor seam established by the Notification Outbox
+/// page tests (see <c>NotificationOutboxPageTests</c>).
+/// </summary>
+public class HealthPageTests : BunitContext
+{
+    private readonly ActorSystem _system = ActorSystem.Create("health-page-tests");
+    private readonly CommunicationService _comms;
+
+    // Mutable scripted reply — individual tests can override before rendering.
+    private NotificationKpiResponse _kpiReply =
+        new("k", true, null, QueueDepth: 12, StuckCount: 4, ParkedCount: 3,
+            DeliveredLastInterval: 88, OldestPendingAge: TimeSpan.FromMinutes(6));
+
+    public HealthPageTests()
+    {
+        _comms = new CommunicationService(
+            Options.Create(new CommunicationOptions()),
+            NullLogger<CommunicationService>.Instance);
+
+        var outbox = _system.ActorOf(Props.Create(() => new ScriptedOutboxActor(this)));
+        _comms.SetNotificationOutbox(outbox);
+        Services.AddSingleton(_comms);
+
+        var aggregator = Substitute.For<ICentralHealthAggregator>();
+        aggregator.GetAllSiteStates()
+            .Returns(new Dictionary<string, SiteHealthState>());
+        Services.AddSingleton(aggregator);
+
+        var siteRepo = Substitute.For<ISiteRepository>();
+        siteRepo.GetAllSitesAsync(Arg.Any<CancellationToken>())
+            .Returns(Task.FromResult<IReadOnlyList<Site>>(new List<Site>()));
+        Services.AddSingleton(siteRepo);
+
+        var claims = new[]
+        {
+            new Claim("Username", "tester"),
+            new Claim(ClaimTypes.Role, "Admin"),
+        };
+        var user = new ClaimsPrincipal(new ClaimsIdentity(claims, "TestAuth"));
+        Services.AddSingleton<AuthenticationStateProvider>(new TestAuthStateProvider(user));
+        Services.AddAuthorizationCore();
+    }
+
+    [Fact]
+    public void Renders_OutboxKpiTiles_WithValues()
+    {
+        var cut = Render<HealthPage>();
+
+        // KPI data arrives via an async actor Ask after first render.
+        cut.WaitForAssertion(() =>
+        {
+            Assert.Contains("Notification Outbox", cut.Markup);
+            Assert.Contains("Queue Depth", cut.Markup);
+            Assert.Contains("Stuck", cut.Markup);
+            Assert.Contains("Parked", cut.Markup);
+            // KPI numeric values surface in the tiles.
+            Assert.Contains(">12<", cut.Markup);  // QueueDepth
+            Assert.Contains(">4<", cut.Markup);   // StuckCount
+            Assert.Contains(">3<", cut.Markup);   // ParkedCount
+        });
+    }
+
+    [Fact]
+    public void OutboxKpiFailure_ShowsGracefulFallback()
+    {
+        _kpiReply = new NotificationKpiResponse(
+            "k", false, "outbox repository unavailable", 0, 0, 0, 0, null);
+
+        var cut = Render<HealthPage>();
+
+        cut.WaitForAssertion(() =>
+        {
+            // Failure must not crash the page; tiles fall back to a dash.
+            Assert.Contains("Notification Outbox", cut.Markup);
+            Assert.Contains("Queue Depth", cut.Markup);
+            Assert.Contains(">—<", cut.Markup);
+        });
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (disposing)
+        {
+            _system.Terminate().Wait(TimeSpan.FromSeconds(5));
+        }
+        base.Dispose(disposing);
+    }
+
+    /// <summary>
+    /// Stand-in for the notification-outbox actor. Replies to the KPI request
+    /// with the test's currently-scripted response.
+    /// </summary>
+    private sealed class ScriptedOutboxActor : ReceiveActor
+    {
+        public ScriptedOutboxActor(HealthPageTests test)
+        {
+            Receive<NotificationKpiRequest>(_ => Sender.Tell(test._kpiReply));
+        }
+    }
+}