fix(tests): record progress events synchronously to remove flake

tests/BSPLocalizationTools.Tests/BatchLocalizationRunnerTests.cs

@@ -19,7 +19,7 @@ public async Task RunAsyncContinuesAfterSkippedItem()
                     new LocalizationRequest(first, "schinese", null, CreateOptions()),
                     new LocalizationRequest(second, "schinese", null, CreateOptions()),
                 ]),
-            new Progress<TranslationProgress>(progressEvents.Add),
+            new ListProgress(progressEvents),
             CancellationToken.None);
 
         Assert.True(results[0].Succeeded);
@@ -119,14 +119,6 @@ public Task<string> CompleteTextAsync(
         }
     }
 
-    private sealed class ListProgress(List<TranslationProgress> events) : IProgress<TranslationProgress>
-    {
-        public void Report(TranslationProgress value)
-        {
-            events.Add(value);
-        }
-    }
-
     private sealed class QueuingSynchronizationContext : SynchronizationContext
     {
         public override void Post(SendOrPostCallback d, object? state)

tests/BSPLocalizationTools.Tests/ListProgress.cs

@@ -0,0 +1,12 @@
+namespace BSPLocalizationTools.Tests;
+
+// Synchronous IProgress so progress events are recorded before the awaited call returns.
+// Progress<T> posts callbacks to the captured SynchronizationContext, which under xUnit can
+// deliver them after the test's assertions have already run.
+internal sealed class ListProgress(List<TranslationProgress> events) : IProgress<TranslationProgress>
+{
+    public void Report(TranslationProgress value)
+    {
+        events.Add(value);
+    }
+}

tests/BSPLocalizationTools.Tests/LocalizationRunnerProgressTests.cs

@@ -19,7 +19,7 @@ public async Task RunAsyncReportsStagesAndOutputPath()
                 "schinese",
                 null,
                 new LLMOptions("gpt-test", "sk-", null, null, "medium", null)),
-            new Progress<TranslationProgress>(progressEvents.Add),
+            new ListProgress(progressEvents),
             CancellationToken.None);
 
         Assert.Equal(Path.Combine(temp.Path, "fake_map_dictionary_schinese.csv"), result.OutputPath);