From 3d2e95b83710a94e78933ed35cb349cf87187cca Mon Sep 17 00:00:00 2001
From: Adam Ratzman <adam@adamratzman.com>
Date: Mon, 14 Apr 2025 14:02:07 -0400
Subject: [PATCH 1/2] Ensure visible trace spans stay sorted by start time

---
 src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs b/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs
index 195ff568cf9..1ecbb812f0f 100644
--- a/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs
+++ b/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs
@@ -80,7 +80,7 @@ private ValueTask<GridItemsProviderResult<SpanWaterfallViewModel>> GetData(GridI
     {
         Debug.Assert(_spanWaterfallViewModels != null);
 
-        var visibleViewModels = new HashSet<SpanWaterfallViewModel>();
+        var visibleViewModels = new SortedSet<SpanWaterfallViewModel>(Comparer<SpanWaterfallViewModel>.Create((a, b) => a.Span.StartTime.CompareTo(b.Span.StartTime)));
         foreach (var viewModel in _spanWaterfallViewModels)
         {
             if (!viewModel.IsHidden && viewModel.MatchesFilter(_filter, GetResourceName, out var matchedDescendents))

From 3ef09984514f5461a8c250b45729f54e00e9201b Mon Sep 17 00:00:00 2001
From: Adam Ratzman <adam@adamratzman.com>
Date: Tue, 15 Apr 2025 12:01:06 -0400
Subject: [PATCH 2/2] Add grid sort order test

---
 .../Components/Pages/TraceDetail.razor.cs     |  3 +-
 .../Pages/TraceDetailsTests.cs                | 56 +++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs b/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs
index 1ecbb812f0f..48218220e22 100644
--- a/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs
+++ b/src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs
@@ -76,7 +76,8 @@ protected override void OnInitialized()
         }
     }
 
-    private ValueTask<GridItemsProviderResult<SpanWaterfallViewModel>> GetData(GridItemsProviderRequest<SpanWaterfallViewModel> request)
+    // Internal to be used in unit tests
+    internal ValueTask<GridItemsProviderResult<SpanWaterfallViewModel>> GetData(GridItemsProviderRequest<SpanWaterfallViewModel> request)
     {
         Debug.Assert(_spanWaterfallViewModels != null);
 
diff --git a/tests/Aspire.Dashboard.Components.Tests/Pages/TraceDetailsTests.cs b/tests/Aspire.Dashboard.Components.Tests/Pages/TraceDetailsTests.cs
index 9e6ea12175a..53d9f4c64b1 100644
--- a/tests/Aspire.Dashboard.Components.Tests/Pages/TraceDetailsTests.cs
+++ b/tests/Aspire.Dashboard.Components.Tests/Pages/TraceDetailsTests.cs
@@ -137,6 +137,62 @@ public async Task Render_ChangeTrace_RowsRendered()
         await AsyncTestHelpers.AssertIsTrueRetryAsync(() => rows.Count == 2, "Expected rows to be rendered.");
     }
 
+    [Fact]
+    public async Task Render_SpansOrderedByStartTime_RowsRenderedInCorrectOrder()
+    {
+        // Arrange
+        SetupTraceDetailsServices();
+
+        var viewport = new ViewportInformation(IsDesktop: true, IsUltraLowHeight: false, IsUltraLowWidth: false);
+
+        var dimensionManager = Services.GetRequiredService<DimensionManager>();
+        dimensionManager.InvokeOnViewportInformationChanged(viewport);
+
+        var telemetryRepository = Services.GetRequiredService<TelemetryRepository>();
+        telemetryRepository.AddTraces(new AddContext(),
+            new RepeatedField<ResourceSpans>
+            {
+                new ResourceSpans
+                {
+                    Resource = CreateResource(),
+                    ScopeSpans =
+                    {
+                        new ScopeSpans
+                        {
+                            Scope = CreateScope(),
+                            Spans =
+                            {
+                                CreateSpan(traceId: "1", spanId: "1-1",
+                                    startTime: s_testTime.AddMinutes(1),
+                                    endTime: s_testTime.AddMinutes(10)),
+                                CreateSpan(traceId: "1", spanId: "1-2",
+                                    startTime: s_testTime.AddMinutes(5),
+                                    endTime: s_testTime.AddMinutes(10), parentSpanId: "1-1"),
+                                CreateSpan(traceId: "1", spanId: "1-3",
+                                    startTime: s_testTime.AddMinutes(2),
+                                    endTime: s_testTime.AddMinutes(6), parentSpanId: "1-1")
+                            }
+                        }
+                    }
+                }
+            });
+
+        // Act
+        var traceId = Convert.ToHexString(Encoding.UTF8.GetBytes("1"));
+        var cut = RenderComponent<TraceDetail>(builder =>
+        {
+            builder.Add(p => p.TraceId, traceId);
+            builder.AddCascadingValue(viewport);
+        });
+
+        var data = await cut.Instance.GetData(new GridItemsProviderRequest<SpanWaterfallViewModel>());
+
+        Assert.Collection(data.Items,
+            item => Assert.Equal("Test span. Id: 1-1", item.Span.Name),
+            item => Assert.Equal("Test span. Id: 1-3", item.Span.Name),
+            item => Assert.Equal("Test span. Id: 1-2", item.Span.Name));
+    }
+
     private void SetupTraceDetailsServices()
     {
         var version = typeof(FluentMain).Assembly.GetName().Version!;