[Fusion] Fix deferred plans rejecting nested lookups below the defer anchor

src/HotChocolate/Fusion/src/Fusion.Execution/Planning/OperationPlanner.Defer.cs

@@ -741,10 +741,11 @@ is not { } providerStep
             lifted,
             droppedStepIds);
 
-        // Record the parent-scope requirements on the descriptor.
+        // Record the parent-scope requirements on the descriptor. A step without a
+        // parent dependency is served entirely by other steps in this incremental plan.
         foreach (var step in rewrittenIncrementalPlan)
         {
-            if (step is not OperationPlanStep operationStep)
+            if (step is not OperationPlanStep operationStep || operationStep.ParentDependencies.IsEmpty)
             {
                 continue;
             }
@@ -1541,7 +1542,8 @@ private static (OperationPlanStep? ConsumingStep, OperationRequirement Requireme
     /// <summary>
     /// Finds every step in <paramref name="incrementalPlanSteps"/> that targets either
     /// <paramref name="anchorPath"/> or the operation root and whose every selected field
-    /// is consumed as a requirement by one of its dependents.
+    /// is consumed as a requirement at or above <paramref name="anchorPath"/> by one of
+    /// its dependents.
     /// </summary>
     private static ImmutableArray<OperationPlanStep> FindDeferRequirementProducers(
         ImmutableList<PlanStep> incrementalPlanSteps,
@@ -1555,7 +1557,7 @@ private static ImmutableArray<OperationPlanStep> FindDeferRequirementProducers(
                 && operationStep.SchemaName is not null
                 && !operationStep.Dependents.IsEmpty
                 && (operationStep.Target.Equals(anchorPath) || operationStep.Target.IsRoot)
-                && IsPureRequirementProducer(operationStep, incrementalPlanSteps))
+                && IsPureRequirementProducer(operationStep, incrementalPlanSteps, anchorPath))
             {
                 producers.Add(operationStep);
             }
@@ -1566,12 +1568,13 @@ private static ImmutableArray<OperationPlanStep> FindDeferRequirementProducers(
 
     /// <summary>
     /// Determines whether every field <paramref name="step"/> selects is consumed as a
-    /// requirement by one of its dependents, meaning the step carries no output of its
-    /// own beyond what those dependents need from it.
+    /// requirement at or above <paramref name="anchorPath"/> by one of its dependents,
+    /// meaning the step carries no output of its own beyond what the enclosing scope can supply.
     /// </summary>
     private static bool IsPureRequirementProducer(
         OperationPlanStep step,
-        ImmutableList<PlanStep> incrementalPlanSteps)
+        ImmutableList<PlanStep> incrementalPlanSteps,
+        SelectionPath anchorPath)
     {
         var ownFields = new HashSet<string>(StringComparer.Ordinal);
         CollectLeafFieldNames(step.Definition.SelectionSet, ownFields);
@@ -1591,6 +1594,13 @@ private static bool IsPureRequirementProducer(
 
             foreach (var (_, requirement) in dependentStep.Requirements)
             {
+                // A requirement below the anchor reads a value this step fetches as
+                // deferred output, which the enclosing scope does not reach.
+                if (!requirement.Path.IsParentOfOrSame(anchorPath))
+                {
+                    continue;
+                }
+
                 var fieldName = requirement.InternalAlias ?? ExtractRootFieldName(requirement.Map.ToString());
 
                 if (fieldName is not null)

src/HotChocolate/Fusion/src/Fusion.Execution/Planning/OperationPlanner.cs

@@ -56,7 +56,7 @@ public OperationPlanner(
         _options = options;
     }
 
-    public static Version Version { get; } = new(2, 2, 0);
+    public static Version Version { get; } = new(2, 3, 0);
 
     internal OperationPlannerOptions Options => _options;
 

src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/DeferTests.cs

@@ -2221,6 +2221,99 @@ ... @defer {
         await MatchSnapshotAsync(gateway, request, result, stableStream: true);
     }
 
+    [Fact]
+    public async Task Defer_Should_ResolveNestedLookupInDeferredPayload_When_DeferredFieldTraversesSubgraphs()
+    {
+        // arrange
+        using var server1 = CreateSourceSchema(
+            "A",
+            b => b.AddQueryType<NestedLookupSourceA.Query>());
+
+        using var server2 = CreateSourceSchema(
+            "B",
+            b => b.AddQueryType<NestedLookupSourceB.Query>());
+
+        using var server3 = CreateSourceSchema(
+            "C",
+            b => b.AddQueryType<NestedLookupSourceC.Query>());
+
+        using var gateway = await CreateCompositeSchemaAsync(
+        [
+            ("A", server1),
+            ("B", server2),
+            ("C", server3)
+        ]);
+
+        // act
+        using var client = GraphQLHttpClient.Create(gateway.CreateClient());
+
+        var request = new OperationRequest(
+            """
+            {
+                products {
+                    name
+                    ... @defer(label: "deeper") {
+                        related {
+                            name
+                        }
+                    }
+                }
+            }
+            """);
+
+        using var result = await client.PostAsync(
+            request,
+            new Uri("http://localhost:5000/graphql"),
+            TestContext.Current.CancellationToken);
+
+        // assert
+        await MatchSnapshotAsync(gateway, request, result, stableStream: true);
+    }
+
+    private static class NestedLookupSourceA
+    {
+        public class Query
+        {
+            public Product[] GetProducts() => [new(1), new(2)];
+
+            [Lookup]
+            [Internal]
+            public Product? GetProductById([ID] int id) => new(id);
+        }
+
+        public record Product([property: ID] int Id);
+    }
+
+    private static class NestedLookupSourceB
+    {
+        public class Query
+        {
+            [Lookup]
+            [Internal]
+            public Product? GetProductById([ID] int id) => new(id);
+        }
+
+        public record Product([property: ID] int Id)
+        {
+            public Product Related => new(Id + 10);
+        }
+    }
+
+    private static class NestedLookupSourceC
+    {
+        public class Query
+        {
+            [Lookup]
+            [Internal]
+            public Product? GetProductById([ID] int id) => new(id);
+        }
+
+        public record Product([property: ID] int Id)
+        {
+            public string Name => $"Product {Id}";
+        }
+    }
+
     private static class MixedRequirementSourceA
     {
         public class Query

src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/DeferTests.Defer_Nested_With_Forwarded_Variable_At_Each_Level.yaml

@@ -514,9 +514,6 @@ operationPlan:
         - 1
       parentNodeId: 1
       requirements:
-        - name: __fusion_1_id
-          selectionMap: >-
-            id
         - name: __fusion_2_id
           selectionMap: >-
             id