Merge all changes

src/Orchestrator/StellaOps.Orchestrator/StellaOps.Orchestrator.Tests/Domain/Mirror/MirrorOperationRecorderTests.cs

@@ -450,7 +450,7 @@ public sealed class InMemoryMirrorEvidenceStoreTests
 
         await store.StoreAsync(evidence);
 
-        Assert.Equal(1, store.Count);
+        Assert.Single(store);
     }
 
     [Fact]
@@ -502,7 +502,7 @@ public sealed class InMemoryMirrorEvidenceStoreTests
 
         store.Clear();
 
-        Assert.Equal(0, store.Count);
+        Assert.Empty(store);
     }
 }
 
@@ -731,7 +731,7 @@ public sealed class MirrorOperationRecorderTests
         Assert.NotNull(result.EvidencePointer);
 
         // Verify evidence was stored
-        Assert.Equal(1, _evidenceStore.Count);
+        Assert.Single(_evidenceStore);
         var evidence = await _evidenceStore.GetAsync(context.OperationId);
         Assert.NotNull(evidence);
         Assert.Equal(MirrorOperationType.BundleExport, evidence.OperationType);

src/Orchestrator/StellaOps.Orchestrator/StellaOps.Orchestrator.Tests/Events/EventPublishingTests.cs

@@ -417,7 +417,7 @@ public class EventPublishingTests
         var result = await store.TryMarkAsync("key-1", TimeSpan.FromMinutes(5), CT);
 
         Assert.True(result);
-        Assert.Equal(1, store.Count);
+        Assert.Single(store);
     }
 
     [Fact]
@@ -429,7 +429,7 @@ public class EventPublishingTests
         var result = await store.TryMarkAsync("key-1", TimeSpan.FromMinutes(5), CT);
 
         Assert.False(result);
-        Assert.Equal(1, store.Count);
+        Assert.Single(store);
     }
 
     [Fact]
@@ -451,7 +451,7 @@ public class EventPublishingTests
         await store.RemoveAsync("key-1", CT);
 
         Assert.False(await store.ExistsAsync("key-1", CT));
-        Assert.Equal(0, store.Count);
+        Assert.Empty(store);
     }
 
     [Fact]
@@ -463,7 +463,7 @@ public class EventPublishingTests
 
         store.Clear();
 
-        Assert.Equal(0, store.Count);
+        Assert.Empty(store);
     }
 
     [Fact]

src/Orchestrator/StellaOps.Orchestrator/StellaOps.Orchestrator.Tests/Events/TimelineEventTests.cs

@@ -243,7 +243,7 @@ public sealed class TimelineEventTests
         // Assert
         Assert.True(result.Success);
         Assert.False(result.Deduplicated);
-        Assert.Equal(1, sink.Count);
+        Assert.Single(sink);
 
         var stored = sink.GetEvents()[0];
         Assert.Equal(evt.EventId, stored.EventId);
@@ -281,7 +281,7 @@ public sealed class TimelineEventTests
         Assert.True(result2.Success);
         Assert.True(result2.Deduplicated);
 
-        Assert.Equal(1, sink.Count);
+        Assert.Single(sink);
     }
 
     [Fact]

src/Orchestrator/StellaOps.Orchestrator/StellaOps.Orchestrator.Tests/Evidence/JobAttestationTests.cs

@@ -414,7 +414,7 @@ public sealed class InMemoryJobAttestationStoreTests
 
         await store.StoreAsync(attestation);
 
-        Assert.Equal(1, store.Count);
+        Assert.Single(store);
     }
 
     [Fact]
@@ -482,7 +482,7 @@ public sealed class InMemoryJobAttestationStoreTests
 
         store.Clear();
 
-        Assert.Equal(0, store.Count);
+        Assert.Empty(store);
     }
 }
 
@@ -552,7 +552,7 @@ public sealed class JobAttestationServiceTests
 
         var result = await _service.GenerateJobCompletionAttestationAsync(request);
 
-        Assert.Equal(1, _store.Count);
+        Assert.Single(_store);
         var stored = await _store.GetAsync(result.Attestation!.AttestationId);
         Assert.NotNull(stored);
     }

src/Orchestrator/StellaOps.Orchestrator/StellaOps.Orchestrator.Tests/Evidence/JobCapsuleTests.cs

@@ -302,7 +302,7 @@ public sealed class InMemoryJobCapsuleStoreTests
 
         await store.StoreAsync(capsule, CancellationToken.None);
 
-        Assert.Equal(1, store.Count);
+        Assert.Single(store);
     }
 
     [Fact]
@@ -358,10 +358,10 @@ public sealed class InMemoryJobCapsuleStoreTests
         var capsule = JobCapsule.Create("tenant-1", Guid.NewGuid(), "test.job", JobCapsuleKind.JobScheduling, inputs);
 
         await store.StoreAsync(capsule, CancellationToken.None);
-        Assert.Equal(1, store.Count);
+        Assert.Single(store);
 
         store.Clear();
 
-        Assert.Equal(0, store.Count);
+        Assert.Empty(store);
     }
 }

src/Orchestrator/StellaOps.Orchestrator/StellaOps.Orchestrator.Tests/Scale/ScaleMetricsTests.cs

@@ -18,7 +18,7 @@ public sealed class ScaleMetricsTests
 
         // Assert
         var percentiles = metrics.GetDispatchLatencyPercentiles("tenant-1");
-        Assert.Equal(1, percentiles.Count);
+        Assert.Single(percentiles);
         Assert.Equal(100, percentiles.P95);
     }
 
@@ -58,7 +58,7 @@ public sealed class ScaleMetricsTests
         var percentiles = metrics.GetDispatchLatencyPercentiles();
 
         // Assert
-        Assert.Equal(0, percentiles.Count);
+        Assert.Empty(percentiles);
         Assert.Equal(0, percentiles.P95);
     }
 
@@ -77,7 +77,7 @@ public sealed class ScaleMetricsTests
 
         // Assert
         Assert.Equal(2, tenant1Percentiles.Count);
-        Assert.Equal(1, tenant2Percentiles.Count);
+        Assert.Single(tenant2Percentiles);
         Assert.Equal(100, tenant2Percentiles.P95);
     }
 
@@ -95,7 +95,7 @@ public sealed class ScaleMetricsTests
 
         // Assert
         var percentiles = metrics.GetDispatchLatencyPercentiles("tenant-1");
-        Assert.Equal(1, percentiles.Count);
+        Assert.Single(percentiles);
         Assert.True(percentiles.P95 >= 10);
     }
 
@@ -210,7 +210,7 @@ public sealed class ScaleMetricsTests
         // Assert
         Assert.Equal(50, snapshot.TotalQueueDepth);
         Assert.Equal(10, snapshot.TotalActiveJobs);
-        Assert.Equal(1, snapshot.DispatchLatency.Count);
+        Assert.Single(snapshot.DispatchLatency);
         Assert.Single(snapshot.QueueDepthByKey);
         Assert.Single(snapshot.ActiveJobsByKey);
     }
@@ -229,7 +229,7 @@ public sealed class ScaleMetricsTests
         // Assert
         var snapshot = metrics.GetSnapshot();
         Assert.Equal(0, snapshot.TotalQueueDepth);
-        Assert.Equal(0, snapshot.DispatchLatency.Count);
+        Assert.Empty(snapshot.DispatchLatency);
     }
 
     [Fact]