[Fusion] Fix conditionals below shared field

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Execution/Nodes/OperationCompiler.cs

@@ -337,7 +337,8 @@ private bool DoesTypeApply(NamedTypeNode? typeCondition, IObjectTypeDefinition t
 
     private static bool IsInternal(FieldNode fieldNode)
     {
-        const string isInternal = "fusion__requirement";
+        const string requirementDirective = "fusion__requirement";
+        const string emptyDirective = "fusion__empty";
         var directives = fieldNode.Directives;
 
         if (directives.Count == 0)
@@ -347,27 +348,41 @@ private static bool IsInternal(FieldNode fieldNode)
 
         if (directives.Count == 1)
         {
-            return directives[0].Name.Value.Equals(isInternal, StringComparison.Ordinal);
+            var name = directives[0].Name.Value;
+            return name.Equals(requirementDirective, StringComparison.Ordinal)
+                || name.Equals(emptyDirective, StringComparison.Ordinal);
         }
 
         if (directives.Count == 2)
         {
-            return directives[0].Name.Value.Equals(isInternal, StringComparison.Ordinal)
-                || directives[1].Name.Value.Equals(isInternal, StringComparison.Ordinal);
+            var name1 = directives[0].Name.Value;
+            var name2 = directives[1].Name.Value;
+            return name1.Equals(requirementDirective, StringComparison.Ordinal)
+                || name1.Equals(emptyDirective, StringComparison.Ordinal)
+                || name2.Equals(requirementDirective, StringComparison.Ordinal)
+                || name2.Equals(emptyDirective, StringComparison.Ordinal);
         }
 
         if (directives.Count == 3)
         {
-            return directives[0].Name.Value.Equals(isInternal, StringComparison.Ordinal)
-                || directives[1].Name.Value.Equals(isInternal, StringComparison.Ordinal)
-                || directives[2].Name.Value.Equals(isInternal, StringComparison.Ordinal);
+            var name1 = directives[0].Name.Value;
+            var name2 = directives[1].Name.Value;
+            var name3 = directives[2].Name.Value;
+            return name1.Equals(requirementDirective, StringComparison.Ordinal)
+                || name1.Equals(emptyDirective, StringComparison.Ordinal)
+                || name2.Equals(requirementDirective, StringComparison.Ordinal)
+                || name2.Equals(emptyDirective, StringComparison.Ordinal)
+                || name3.Equals(requirementDirective, StringComparison.Ordinal)
+                || name3.Equals(emptyDirective, StringComparison.Ordinal);
         }
 
         for (var i = 0; i < directives.Count; i++)
         {
             var directive = directives[i];
+            var name = directive.Name.Value;
 
-            if (directive.Name.Value.Equals(isInternal, StringComparison.Ordinal))
+            if (name.Equals(requirementDirective, StringComparison.Ordinal)
+                || name.Equals(emptyDirective, StringComparison.Ordinal))
             {
                 return true;
             }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Planning/Backlog.cs

@@ -1,4 +1,5 @@
 using System.Collections.Immutable;
+using HotChocolate.Fusion.Planning.Partitioners;
 
 namespace HotChocolate.Fusion.Planning;
 
@@ -52,7 +53,7 @@ public Backlog Pop(out WorkItem workItem)
     /// their own operation steps on other schemas.
     /// </summary>
     public Backlog PushUnresolvable(
-        ImmutableStack<SelectionSet> unresolvable,
+        ImmutableStack<ConditionedSelectionSet> unresolvable,
         string fromSchema,
         int parentDepth)
     {
@@ -63,16 +64,18 @@ public Backlog PushUnresolvable(
 
         var backlog = this;
 
-        foreach (var selectionSet in unresolvable.Reverse())
+        foreach (var entry in unresolvable.Reverse())
         {
+            var selectionSet = entry.SelectionSet;
             var workItem = new OperationWorkItem(
                 selectionSet.Path.IsRoot
                     ? OperationWorkItemKind.Root
                     : OperationWorkItemKind.Lookup,
                 selectionSet,
                 FromSchema: fromSchema)
             {
-                ParentDepth = parentDepth
+                ParentDepth = parentDepth,
+                Conditions = entry.Conditions
             };
             backlog = backlog.Push(workItem);
         }
@@ -85,7 +88,7 @@ public Backlog PushUnresolvable(
     /// which may need lookup steps to satisfy.
     /// </summary>
     public Backlog PushRequirements(
-        ImmutableStack<FieldSelection> fieldsWithRequirements,
+        ImmutableStack<ConditionedFieldSelection> fieldsWithRequirements,
         int stepId,
         int parentDepth)
     {
@@ -96,11 +99,12 @@ public Backlog PushRequirements(
 
         var backlog = this;
 
-        foreach (var selection in fieldsWithRequirements.Reverse())
+        foreach (var entry in fieldsWithRequirements.Reverse())
         {
-            var workItem = new FieldRequirementWorkItem(selection, stepId)
+            var workItem = new FieldRequirementWorkItem(entry.FieldSelection, stepId)
             {
-                ParentDepth = parentDepth
+                ParentDepth = parentDepth,
+                Conditions = entry.Conditions
             };
             backlog = backlog.Push(workItem);
         }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Planning/FieldWithRequirementWorkItem.cs

@@ -1,3 +1,4 @@
+using HotChocolate.Fusion.Execution.Nodes;
 using HotChocolate.Fusion.Types.Metadata;
 
 namespace HotChocolate.Fusion.Planning;
@@ -8,6 +9,8 @@ internal sealed record FieldRequirementWorkItem(
     Lookup? Lookup = null)
     : WorkItem
 {
+    public ExecutionNodeCondition[] Conditions { get; init; } = [];
+
     public int StepIndex => StepId - 1;
 
     public override double Cost => Lookup is null ? 1 : 2;