Implement in-process multi-dataset sync isolation across core, network, persistence, and tests

tests/ZB.MOM.WW.CBDDC.Core.Tests/OplogEntryTests.cs

@@ -63,11 +63,35 @@ public class OplogEntryTests
     ///     Verifies that an entry is valid when its stored hash matches computed content.
     /// </summary>
     [Fact]
-    public void IsValid_ShouldReturnTrue_WhenHashMatches()
-    {
-        var timestamp = new HlcTimestamp(100, 0, "node-1");
-        var entry = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev");
-
-        entry.IsValid().ShouldBeTrue();
-    }
-}
+    public void IsValid_ShouldReturnTrue_WhenHashMatches()
+    {
+        var timestamp = new HlcTimestamp(100, 0, "node-1");
+        var entry = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev");
+
+        entry.IsValid().ShouldBeTrue();
+    }
+
+    /// <summary>
+    ///     Verifies that entries default to the primary dataset when dataset is omitted.
+    /// </summary>
+    [Fact]
+    public void Constructor_ShouldDefaultDatasetId_ToPrimary()
+    {
+        var entry = new OplogEntry("col", "key", OperationType.Put, null, new HlcTimestamp(1, 0, "node"), "prev");
+
+        entry.DatasetId.ShouldBe(DatasetId.Primary);
+    }
+
+    /// <summary>
+    ///     Verifies that hash computation includes dataset identity to prevent cross-dataset collisions.
+    /// </summary>
+    [Fact]
+    public void ComputeHash_ShouldDiffer_WhenDatasetDiffers()
+    {
+        var timestamp = new HlcTimestamp(100, 0, "node-1");
+        var primary = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev", datasetId: "primary");
+        var logs = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev", datasetId: "logs");
+
+        logs.Hash.ShouldNotBe(primary.Hash);
+    }
+}