From fb2a792b3bde44f9cb2d0ef293ed648200c766aa Mon Sep 17 00:00:00 2001
From: Michael Staib <michael@chillicream.com>
Date: Wed, 25 Feb 2026 12:12:49 +0000
Subject: [PATCH 1/2] Fix IsProjected optimizer for composite fields

---
 .../IsProjectedProjectionOptimizer.cs         |  7 +-
 .../Issue6329ReproTests.cs                    | 71 +++++++++++++++++++
 2 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 src/HotChocolate/Data/test/Data.Projections.SqlServer.Tests/Issue6329ReproTests.cs

diff --git a/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs b/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs
index 36a108fe8a9..ca1d88160ef 100644
--- a/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs
+++ b/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs
@@ -1,5 +1,6 @@
 using HotChocolate.Execution.Processing;
 using HotChocolate.Language;
+using HotChocolate.Types;
 
 namespace HotChocolate.Data.Projections.Optimizers;
 
@@ -38,13 +39,17 @@ public Selection RewriteSelection(
             }
 
             var field = context.TypeContext.Fields[fieldName];
+            var selectionSet = field.Type.NamedType().IsCompositeType()
+                ? new SelectionSetNode([])
+                : null;
+
             var fieldNode = new FieldNode(
                 null,
                 new NameNode(fieldName),
                 new NameNode(alias),
                 [],
                 [],
-                null);
+                selectionSet);
 
             var nodesPipeline = context.CompileResolverPipeline(field, fieldNode);
 
diff --git a/src/HotChocolate/Data/test/Data.Projections.SqlServer.Tests/Issue6329ReproTests.cs b/src/HotChocolate/Data/test/Data.Projections.SqlServer.Tests/Issue6329ReproTests.cs
new file mode 100644
index 00000000000..262f183232d
--- /dev/null
+++ b/src/HotChocolate/Data/test/Data.Projections.SqlServer.Tests/Issue6329ReproTests.cs
@@ -0,0 +1,71 @@
+using HotChocolate.Execution;
+using Microsoft.EntityFrameworkCore;
+
+namespace HotChocolate.Data.Projections;
+
+public class Issue6329ReproTests
+{
+    private readonly SchemaCache _cache = new();
+
+    private readonly BookWithProjectedAuthor[] _books =
+    [
+        new()
+        {
+            Id = 1,
+            Title = "Book",
+            Author = new AuthorWithProjectedId
+            {
+                Id = 10,
+                Name = "Author"
+            }
+        }
+    ];
+
+    [Fact]
+    public async Task IsProjected_SubObject_Can_Be_Omitted_From_Selection()
+    {
+        var tester = _cache.CreateSchema(
+            _books,
+            onModelCreating: modelBuilder =>
+                modelBuilder.Entity<BookWithProjectedAuthor>().OwnsOne(x => x.Author),
+            usePaging: true);
+
+        var result = await tester.ExecuteAsync(
+            OperationRequestBuilder.New()
+                .SetDocument(
+                    """
+                    {
+                      root {
+                        edges {
+                          node {
+                            id
+                          }
+                        }
+                      }
+                    }
+                    """)
+                .Build());
+
+        var operationResult = result.ExpectOperationResult();
+        Assert.Empty(operationResult.Errors ?? []);
+    }
+
+    public class BookWithProjectedAuthor
+    {
+        public int Id { get; set; }
+
+        public string Title { get; set; } = string.Empty;
+
+        [IsProjected(true)]
+        public AuthorWithProjectedId Author { get; set; } = new();
+    }
+
+    [Owned]
+    public class AuthorWithProjectedId
+    {
+        [IsProjected(true)]
+        public int Id { get; set; }
+
+        public string Name { get; set; } = string.Empty;
+    }
+}

From 0443ac47c32b31639fe93c3b91870ce4ea84cd8a Mon Sep 17 00:00:00 2001
From: Michael Staib <michael@chillicream.com>
Date: Fri, 27 Feb 2026 12:29:32 +0100
Subject: [PATCH 2/2] fix

---
 .../Optimizers/IsProjectedProjectionOptimizer.cs     | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs b/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs
index ca1d88160ef..8a9aceb0583 100644
--- a/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs
+++ b/src/HotChocolate/Data/src/Data/Projections/Optimizers/IsProjectedProjectionOptimizer.cs
@@ -39,9 +39,13 @@ public Selection RewriteSelection(
             }
 
             var field = context.TypeContext.Fields[fieldName];
-            var selectionSet = field.Type.NamedType().IsCompositeType()
-                ? new SelectionSetNode([])
-                : null;
+
+            // Only inject leaf fields. Forcing internal object projections can create
+            // invalid EF Core tracking shapes (e.g. owned entities without owner materialization).
+            if (field.Type.NamedType().IsCompositeType())
+            {
+                continue;
+            }
 
             var fieldNode = new FieldNode(
                 null,
@@ -49,7 +53,7 @@ public Selection RewriteSelection(
                 new NameNode(alias),
                 [],
                 [],
-                selectionSet);
+                null);
 
             var nodesPipeline = context.CompileResolverPipeline(field, fieldNode);