feat(ui): add Node column + filter to NotificationOutbox grid

src/ScadaLink.CentralUI/Components/Pages/Notifications/NotificationReport.razor

@@ -60,6 +60,16 @@
                     <input id="no-list" type="text" class="form-control form-control-sm"
                            style="min-width: 140px;" placeholder="Any" @bind="_listFilter" />
                 </div>
+                @* Task 16: free-text Node filter — exact match against the
+                   notification's SourceNode column. Sites + central nodes
+                   both flow through this single input. *@
+                <div class="col-auto">
+                    <label class="form-label small mb-1" for="no-node">Node</label>
+                    <input id="no-node" type="text" class="form-control form-control-sm"
+                           style="min-width: 140px;" placeholder="Any"
+                           data-test="notif-filter-node"
+                           @bind="_nodeFilter" />
+                </div>
                 <div class="col-auto">
                     <label class="form-label small mb-1" for="no-from">From</label>
                     <input id="no-from" type="datetime-local" class="form-control form-control-sm"
@@ -131,6 +141,7 @@
                         <th>Status</th>
                         <th class="text-end">Retries</th>
                         <th>Source site</th>
+                        <th>Node</th>
                         <th>Created</th>
                         <th>Delivered</th>
                         <th class="text-end">Actions</th>
@@ -162,6 +173,7 @@
                             </td>
                             <td class="text-end font-monospace">@n.RetryCount</td>
                             <td><span class="small">@SiteName(n.SourceSiteId)</span></td>
+                            <td><span class="small">@(n.SourceNode ?? "—")</span></td>
                             <td><TimestampDisplay Value="@n.CreatedAt" Format="yyyy-MM-dd HH:mm" /></td>
                             <td><TimestampDisplay Value="@n.DeliveredAt" Format="yyyy-MM-dd HH:mm" NullText="—" /></td>
                             <td class="text-end" @ondblclick:stopPropagation="true">
@@ -253,6 +265,9 @@
                         <dt class="col-sm-3">Source site</dt>
                         <dd class="col-sm-9">@SiteName(d.SourceSiteId)</dd>
 
+                        <dt class="col-sm-3">Source node</dt>
+                        <dd class="col-sm-9">@(string.IsNullOrEmpty(d.SourceNode) ? "—" : d.SourceNode)</dd>
+
                         <dt class="col-sm-3">Source instance</dt>
                         <dd class="col-sm-9">@(string.IsNullOrEmpty(d.SourceInstanceId) ? "—" : d.SourceInstanceId)</dd>
 
@@ -372,6 +387,7 @@
     private string _siteFilter = string.Empty;
     private string _listFilter = string.Empty;
     private string _subjectFilter = string.Empty;
+    private string _nodeFilter = string.Empty;
     private bool _stuckOnly;
     private DateTime? _fromFilter;
     private DateTime? _toFilter;
@@ -422,7 +438,8 @@
                 From: ToUtc(_fromFilter),
                 To: ToUtc(_toFilter),
                 PageNumber: _pageNumber,
-                PageSize: _pageSize);
+                PageSize: _pageSize,
+                SourceNodeFilter: NullIfEmpty(_nodeFilter));
 
             var response = await CommunicationService.QueryNotificationOutboxAsync(request);
             if (response.Success)
@@ -597,6 +614,7 @@
         _siteFilter = string.Empty;
         _listFilter = string.Empty;
         _subjectFilter = string.Empty;
+        _nodeFilter = string.Empty;
         _stuckOnly = false;
         _fromFilter = null;
         _toFilter = null;
@@ -608,6 +626,7 @@
         !string.IsNullOrEmpty(_siteFilter) ||
         !string.IsNullOrEmpty(_listFilter) ||
         !string.IsNullOrEmpty(_subjectFilter) ||
+        !string.IsNullOrEmpty(_nodeFilter) ||
         _stuckOnly ||
         _fromFilter != null ||
         _toFilter != null;

src/ScadaLink.Commons/Messages/Notification/NotificationOutboxQueries.cs

@@ -17,7 +17,8 @@ public record NotificationOutboxQueryRequest(
     DateTimeOffset? From,
     DateTimeOffset? To,
     int PageNumber,
-    int PageSize);
+    int PageSize,
+    string? SourceNodeFilter = null);
 
 /// <summary>
 /// A single notification row summarised for outbox UI display.
@@ -34,7 +35,8 @@ public record NotificationSummary(
     string? SourceInstanceId,
     DateTimeOffset CreatedAt,
     DateTimeOffset? DeliveredAt,
-    bool IsStuck);
+    bool IsStuck,
+    string? SourceNode = null);
 
 /// <summary>
 /// Central -> Outbox UI: paginated response for a <see cref="NotificationOutboxQueryRequest"/>.

src/ScadaLink.Commons/Types/Notifications/NotificationOutboxFilter.cs

@@ -18,6 +18,11 @@ namespace ScadaLink.Commons.Types.Notifications;
 /// <param name="StuckCutoff">Rows with <c>CreatedAt</c> older than this count as stuck.</param>
 /// <param name="From">Inclusive lower bound on <c>CreatedAt</c>.</param>
 /// <param name="To">Inclusive upper bound on <c>CreatedAt</c>.</param>
+/// <param name="SourceNode">
+/// Restrict to notifications originating at a specific cluster node (e.g.
+/// <c>"central-a"</c>, <c>"site-plant-a-node-a"</c>). Exact match; <c>null</c>
+/// means "do not constrain".
+/// </param>
 public record NotificationOutboxFilter(
     NotificationStatus? Status = null,
     NotificationType? Type = null,
@@ -27,4 +32,5 @@ public record NotificationOutboxFilter(
     bool StuckOnly = false,
     DateTimeOffset? StuckCutoff = null,
     DateTimeOffset? From = null,
-    DateTimeOffset? To = null);
+    DateTimeOffset? To = null,
+    string? SourceNode = null);

src/ScadaLink.ConfigurationDatabase/Repositories/NotificationOutboxRepository.cs

@@ -83,6 +83,13 @@ public class NotificationOutboxRepository : INotificationOutboxRepository
             query = query.Where(n => n.SourceSiteId == filter.SourceSiteId);
         }
 
+        // Task 16: SourceNode is exact-match like SourceSiteId. Rows with NULL
+        // SourceNode (legacy / unconfigured) are excluded when the filter is set.
+        if (!string.IsNullOrEmpty(filter.SourceNode))
+        {
+            query = query.Where(n => n.SourceNode == filter.SourceNode);
+        }
+
         if (!string.IsNullOrEmpty(filter.ListName))
         {
             query = query.Where(n => n.ListName == filter.ListName);

src/ScadaLink.NotificationOutbox/NotificationOutboxActor.cs

@@ -626,7 +626,8 @@ public class NotificationOutboxActor : ReceiveActor, IWithTimers
             StuckOnly: request.StuckOnly,
             StuckCutoff: request.StuckOnly ? StuckCutoff(now) : null,
             From: request.From,
-            To: request.To);
+            To: request.To,
+            SourceNode: request.SourceNodeFilter);
 
         using var scope = _serviceProvider.CreateScope();
         var repository = scope.ServiceProvider.GetRequiredService<INotificationOutboxRepository>();
@@ -646,7 +647,8 @@ public class NotificationOutboxActor : ReceiveActor, IWithTimers
                 row.SourceInstanceId,
                 row.CreatedAt,
                 row.DeliveredAt,
-                IsStuck: IsStuck(row, stuckCutoff)))
+                IsStuck: IsStuck(row, stuckCutoff),
+                SourceNode: row.SourceNode))
             .ToList();
 
         return new NotificationOutboxQueryResponse(

tests/ScadaLink.NotificationOutbox.Tests/NotificationOutboxActorQueryTests.cs

@@ -149,6 +149,45 @@ public class NotificationOutboxActorQueryTests : TestKit
             1, 50, Arg.Any<CancellationToken>());
     }
 
+    [Fact]
+    public void Query_PassesSourceNodeFilter_AndProjectsSourceNodeOntoSummary()
+    {
+        // Task 16: the Notifications page's new Node filter input pushes a
+        // value into NotificationOutboxQueryRequest.SourceNodeFilter; the actor
+        // must thread it onto NotificationOutboxFilter.SourceNode AND mirror
+        // the row's SourceNode column onto the response summaries.
+        var row = MakeNotification(status: NotificationStatus.Pending);
+        row.SourceNode = "central-a";
+        _repository.QueryAsync(
+                Arg.Any<NotificationOutboxFilter>(), Arg.Any<int>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
+            .Returns(((IReadOnlyList<Notification>)new[] { row }, 1));
+        var actor = CreateActor();
+
+        actor.Tell(
+            new NotificationOutboxQueryRequest(
+                CorrelationId: "corr-node",
+                StatusFilter: null,
+                TypeFilter: null,
+                SourceSiteFilter: null,
+                ListNameFilter: null,
+                StuckOnly: false,
+                SubjectKeyword: null,
+                From: null,
+                To: null,
+                PageNumber: 1,
+                PageSize: 50,
+                SourceNodeFilter: "central-a"),
+            TestActor);
+
+        var response = ExpectMsg<NotificationOutboxQueryResponse>();
+        Assert.True(response.Success);
+        Assert.Equal("central-a", response.Notifications.Single().SourceNode);
+
+        _repository.Received(1).QueryAsync(
+            Arg.Is<NotificationOutboxFilter>(f => f.SourceNode == "central-a"),
+            1, 50, Arg.Any<CancellationToken>());
+    }
+
     [Fact]
     public void Query_RepositoryThrows_RepliesFailureWithEmptyList()
     {