diff --git a/src/modules/persistence/Elsa.Persistence.MongoDb/Assembly.cs b/src/modules/persistence/Elsa.Persistence.MongoDb/Assembly.cs
new file mode 100644
index 00000000..37aa2a17
--- /dev/null
+++ b/src/modules/persistence/Elsa.Persistence.MongoDb/Assembly.cs
@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Elsa.MongoDb.UnitTests")]
diff --git a/src/modules/persistence/Elsa.Persistence.MongoDb/Common/MongoDbStore.cs b/src/modules/persistence/Elsa.Persistence.MongoDb/Common/MongoDbStore.cs
index af4371a0..98819401 100644
--- a/src/modules/persistence/Elsa.Persistence.MongoDb/Common/MongoDbStore.cs
+++ b/src/modules/persistence/Elsa.Persistence.MongoDb/Common/MongoDbStore.cs
@@ -437,19 +437,24 @@ private IQueryable<TDocument> GetQueryableCollection(bool tenantAgnostic = false
         {
             var tenant = tenantAccessor.Tenant;
             var tenantId = tenant?.Id.EmptyToNull();
-            queryable = queryable.Where(x => (x as Entity)!.TenantId == tenantId);
+            queryable = ApplyTenantFilter(queryable, tenantId);
         }
 
         return queryable;
     }
 
+    internal static IQueryable<TDocument> ApplyTenantFilter(IQueryable<TDocument> queryable, string? tenantId)
+    {
+        return queryable.Where(x => (x as Entity)!.TenantId == tenantId || (x as Entity)!.TenantId == Tenant.AgnosticTenantId);
+    }
+
     private void ApplyTenantId(TDocument document)
     {
         var tenant = tenantAccessor.Tenant;
         var tenantId = tenant?.Id;
 
         if (document is Entity tenantDocument)
-            tenantDocument.TenantId = tenantId.EmptyToNull();
+            ApplyTenantId(tenantDocument, tenantId);
     }
 
     private void ApplyTenantId(IEnumerable<TDocument> documents)
@@ -460,7 +465,19 @@ private void ApplyTenantId(IEnumerable<TDocument> documents)
         foreach (var document in documents)
         {
             if (document is Entity tenantDocument)
-                tenantDocument.TenantId = tenantId.EmptyToNull();
+                ApplyTenantId(tenantDocument, tenantId);
         }
     }
+
+    private static void ApplyTenantId(Entity tenantDocument, string? tenantId)
+    {
+        if (tenantDocument.TenantId == Tenant.AgnosticTenantId)
+            return;
+
+        // Preserve explicitly scoped entities and only stamp ambient tenant IDs on unscoped entities.
+        if (tenantDocument.TenantId != null)
+            return;
+
+        tenantDocument.TenantId = tenantId.EmptyToNull();
+    }
 }
diff --git a/test/modules/persistence/Elsa.MongoDb.UnitTests/MongoKeyValueStoreTests.cs b/test/modules/persistence/Elsa.MongoDb.UnitTests/MongoKeyValueStoreTests.cs
index 904b7972..f826fd86 100644
--- a/test/modules/persistence/Elsa.MongoDb.UnitTests/MongoKeyValueStoreTests.cs
+++ b/test/modules/persistence/Elsa.MongoDb.UnitTests/MongoKeyValueStoreTests.cs
@@ -1,4 +1,5 @@
 using Elsa.Common.Multitenancy;
+using Elsa.Common.Entities;
 using Elsa.KeyValues.Entities;
 using Elsa.Persistence.MongoDb.Common;
 using Elsa.Persistence.MongoDb.Modules.Runtime;
@@ -35,4 +36,89 @@ public async Task SaveAsync_WithSerializedKeyValuePairDocument_DoesNotThrowExcep
 
         Assert.Null(exception);
     }
+}
+
+public class MongoDbStoreTenantTests
+{
+    [Fact(DisplayName = "When saving an agnostic entity, preserve the agnostic tenant marker")]
+    public async Task SaveAsync_WithAgnosticTenant_PreservesAgnosticMarker()
+    {
+        var mongoCollectionMock = Substitute.For<IMongoCollection<TestEntity>>();
+        mongoCollectionMock.FindOneAndReplaceAsync(
+                Arg.Any<FilterDefinition<TestEntity>>(),
+                Arg.Any<TestEntity>(),
+                Arg.Any<FindOneAndReplaceOptions<TestEntity>>()
+            )
+            .Returns(callInfo => callInfo.Arg<TestEntity>());
+
+        var tenantAccessorMock = Substitute.For<ITenantAccessor>();
+        tenantAccessorMock.Tenant.Returns(new Tenant { Id = "tenant-a", Name = "tenant-a" });
+        var store = new MongoDbStore<TestEntity>(mongoCollectionMock, tenantAccessorMock);
+        var entity = new TestEntity { Id = "1", TenantId = Tenant.AgnosticTenantId };
+
+        await store.SaveAsync(entity);
+
+        Assert.Equal(Tenant.AgnosticTenantId, entity.TenantId);
+    }
+
+    [Fact(DisplayName = "When saving an unscoped entity under a tenant, stamp ambient tenant")]
+    public async Task SaveAsync_WithNullTenant_StampsAmbientTenant()
+    {
+        var mongoCollectionMock = Substitute.For<IMongoCollection<TestEntity>>();
+        mongoCollectionMock.FindOneAndReplaceAsync(
+                Arg.Any<FilterDefinition<TestEntity>>(),
+                Arg.Any<TestEntity>(),
+                Arg.Any<FindOneAndReplaceOptions<TestEntity>>()
+            )
+            .Returns(callInfo => callInfo.Arg<TestEntity>());
+
+        var tenantAccessorMock = Substitute.For<ITenantAccessor>();
+        tenantAccessorMock.Tenant.Returns(new Tenant { Id = "tenant-a", Name = "tenant-a" });
+        var store = new MongoDbStore<TestEntity>(mongoCollectionMock, tenantAccessorMock);
+        var entity = new TestEntity { Id = "1", TenantId = null };
+
+        await store.SaveAsync(entity);
+
+        Assert.Equal("tenant-a", entity.TenantId);
+    }
+
+    [Fact(DisplayName = "Tenant filter includes tenant-specific and agnostic records")]
+    public void ApplyTenantFilter_WithConcreteTenant_IncludesAgnostic()
+    {
+        var documents = new[]
+        {
+            new TestEntity { Id = "specific", TenantId = "tenant-a" },
+            new TestEntity { Id = "agnostic", TenantId = Tenant.AgnosticTenantId },
+            new TestEntity { Id = "other", TenantId = "tenant-b" },
+            new TestEntity { Id = "null", TenantId = null }
+        }.AsQueryable();
+
+        var filtered = MongoDbStore<TestEntity>.ApplyTenantFilter(documents, "tenant-a");
+        var ids = filtered.Select(x => x.Id).ToList();
+
+        Assert.Contains("specific", ids);
+        Assert.Contains("agnostic", ids);
+        Assert.DoesNotContain("other", ids);
+        Assert.DoesNotContain("null", ids);
+    }
+
+    [Fact(DisplayName = "Tenant filter includes null and agnostic when ambient tenant is agnostic")]
+    public void ApplyTenantFilter_WithAgnosticTenant_IncludesNullAndAgnostic()
+    {
+        var documents = new[]
+        {
+            new TestEntity { Id = "specific", TenantId = "tenant-a" },
+            new TestEntity { Id = "agnostic", TenantId = Tenant.AgnosticTenantId },
+            new TestEntity { Id = "null", TenantId = null }
+        }.AsQueryable();
+
+        var filtered = MongoDbStore<TestEntity>.ApplyTenantFilter(documents, null);
+        var ids = filtered.Select(x => x.Id).ToList();
+
+        Assert.Contains("agnostic", ids);
+        Assert.Contains("null", ids);
+        Assert.DoesNotContain("specific", ids);
+    }
+
+    public class TestEntity : Entity;
 }
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