Added more robust extensibility to extend mutation errors.

src/HotChocolate/ApolloFederation/src/ApolloFederation/FederationTypeInterceptor.cs

@@ -42,6 +42,7 @@ internal sealed class FederationTypeInterceptor : TypeInterceptor
     private readonly List<ObjectType> _entityTypes = new();
     private IDescriptorContext _context = default!;
     private ITypeInspector _typeInspector = default!;
+    private ObjectType _queryType = default!;
 
     internal override void InitializeContext(
         IDescriptorContext context,
@@ -84,6 +85,17 @@ public override void OnTypesInitialized()
         }
     }
 
+    internal override void OnAfterResolveRootType(
+        ITypeCompletionContext completionContext,
+        ObjectTypeDefinition definition,
+        OperationType operationType)
+    {
+        if (operationType is OperationType.Query)
+        {
+            _queryType = (ObjectType) completionContext.Type;
+        }
+    }
+
     public override void OnBeforeCompleteType(
         ITypeCompletionContext completionContext,
         DefinitionBase definition)
@@ -159,7 +171,7 @@ private void AddServiceTypeToQueryType(
         ITypeCompletionContext completionContext,
         DefinitionBase? definition)
     {
-        if (completionContext.IsQueryType == true &&
+        if (ReferenceEquals(completionContext.Type, _queryType) &&
             definition is ObjectTypeDefinition objectTypeDefinition)
         {
             var serviceFieldDescriptor = ObjectFieldDescriptor.New(

src/HotChocolate/Caching/src/Caching/CacheControlValidationTypeInterceptor.cs

@@ -1,12 +1,28 @@
 using HotChocolate.Configuration;
+using HotChocolate.Language;
 using HotChocolate.Types;
 using HotChocolate.Types.Descriptors.Definitions;
+using IHasDirectives = HotChocolate.Types.IHasDirectives;
 
 namespace HotChocolate.Caching;
 
 internal sealed class CacheControlValidationTypeInterceptor : TypeInterceptor
 {
-    public override void OnValidateType(ITypeSystemObjectContext validationContext,
+    private ITypeCompletionContext _queryContext = default!;
+
+    internal override void OnAfterResolveRootType(
+        ITypeCompletionContext completionContext,
+        ObjectTypeDefinition definition,
+        OperationType operationType)
+    {
+        if (operationType is OperationType.Query)
+        {
+            _queryContext = completionContext;
+        }
+    }
+
+    public override void OnValidateType(
+        ITypeSystemObjectContext validationContext,
         DefinitionBase definition)
     {
         if (validationContext.IsIntrospectionType)
@@ -18,7 +34,7 @@ public override void OnValidateType(ITypeSystemObjectContext validationContext,
         {
             case ObjectType objectType:
             {
-                var isQueryType = validationContext is ITypeCompletionContext { IsQueryType: true };
+                var isQueryType = ReferenceEquals(validationContext, _queryContext);
 
                 ValidateCacheControlOnType(validationContext, objectType);
 

src/HotChocolate/Core/src/Authorization/AuthorizationTypeInterceptor.cs

@@ -31,6 +31,7 @@ internal sealed partial class AuthorizationTypeInterceptor : TypeInterceptor
     private TypeRegistry _typeRegistry = default!;
     private TypeLookup _typeLookup = default!;
     private ExtensionData _schemaContextData = default!;
+    private ITypeCompletionContext _queryContext = default!;
 
     internal override uint Position => uint.MaxValue;
 
@@ -102,13 +103,24 @@ public override void OnBeforeCompleteTypes()
         FindFieldsAndApplyAuthMiddleware(state);
     }
 
+    internal override void OnAfterResolveRootType(
+        ITypeCompletionContext completionContext,
+        ObjectTypeDefinition definition,
+        OperationType operationType)
+    {
+        if (operationType is OperationType.Query)
+        {
+            _queryContext = completionContext;
+        }
+    }
+
     public override void OnBeforeCompleteType(
         ITypeCompletionContext completionContext,
         DefinitionBase definition)
     {
         // last in the initialization we need to intercept the query type and ensure that
         // authorization configuration is applied to the special introspection and node fields.
-        if ((completionContext.IsQueryType ?? false) &&
+        if (ReferenceEquals(_queryContext, completionContext) &&
             definition is ObjectTypeDefinition typeDef)
         {
             var state = _state ?? throw ThrowHelper.StateNotInitialized();

src/HotChocolate/Core/src/Types.Mutations/MutationConventionTypeInterceptor.cs

@@ -55,25 +55,17 @@ public override void OnBeforeRegisterDependencies(
     public override void OnAfterCompleteTypeNames()
         => _mutations = _context.ContextData.GetMutationFields();
 
-    internal override void OnAfterResolveRootType(
-        ITypeCompletionContext completionContext,
-        DefinitionBase? definition,
-        OperationType operationType)
+    internal override void OnBeforeCompleteMutation(
+        ITypeCompletionContext completionContext, 
+        ObjectTypeDefinition definition)
     {
-        // if the type initialization resolved the root type we will capture its definition
-        // so we can use it after the type extensions are merged into this type.
-        if (operationType is OperationType.Mutation)
-        {
-            _mutationTypeDef = (ObjectTypeDefinition)definition!;
-        }
-
         // we need to capture a completion context to resolve types.
         // any context will do.
         _completionContext ??= completionContext;
-    }
-
-    public override void OnAfterMergeTypeExtensions()
-    {
+        _mutationTypeDef = definition;
+        
+        base.OnBeforeCompleteMutation(completionContext, definition);
+        
         // if we have found a mutation type we will start applying the mutation conventions
         // on the mutations.
         if (_mutationTypeDef is not null)

src/HotChocolate/Core/src/Types/Configuration/AggregateTypeInterceptor.cs

@@ -259,7 +259,7 @@ public override void OnAfterCompleteName(
 
     internal override void OnAfterResolveRootType(
         ITypeCompletionContext completionContext,
-        DefinitionBase definition,
+        ObjectTypeDefinition definition,
         OperationType operationType)
     {
         ref var first = ref GetReference();
@@ -307,6 +307,19 @@ public override void OnAfterMergeTypeExtensions()
         }
     }
 
+    internal override void OnBeforeCompleteMutation(
+        ITypeCompletionContext completionContext,
+        ObjectTypeDefinition definition)
+    {
+        ref var first = ref GetReference();
+        var length = _typeInterceptors.Length;
+
+        for (var i = 0; i < length; i++)
+        {
+            Unsafe.Add(ref first, i).OnBeforeCompleteMutation(completionContext, definition);
+        }
+    }
+
     public override void OnBeforeCompleteTypes()
     {
         ref var first = ref GetReference();

src/HotChocolate/Core/src/Types/Configuration/Contracts/ITypeCompletionContext.cs

@@ -14,21 +14,6 @@ namespace HotChocolate.Configuration;
 /// </summary>
 public interface ITypeCompletionContext : ITypeSystemObjectContext
 {
-    /// <summary>
-    /// Defines if the type that is being completed is the query type.
-    /// </summary>
-    bool? IsQueryType { get; }
-
-    /// <summary>
-    /// Defines if the type that is being completed is the mutation type.
-    /// </summary>
-    bool? IsMutationType { get; }
-
-    /// <summary>
-    /// Defines if the type that is being completed is the subscription type.
-    /// </summary>
-    bool? IsSubscriptionType { get; }
-
     /// <summary>
     /// Global middleware components.
     /// </summary>

src/HotChocolate/Core/src/Types/Configuration/TypeInitializer.cs

@@ -373,6 +373,15 @@ t.Type is INamedType n &&
         }
 
         _interceptor.OnAfterMergeTypeExtensions();
+
+        var mutationType = _rootTypes.FirstOrDefault(t => t.Kind == OperationType.Mutation);
+
+        if (mutationType.IsInitialized)
+        {
+            _interceptor.OnBeforeCompleteMutation(
+                mutationType.Type, 
+                ((ObjectType)mutationType.Type.Type).Definition!);
+        }
     }
 
     private void MergeTypeExtension(
@@ -658,12 +667,15 @@ public RegisteredRootType(
             Context = context;
             Type = type;
             Kind = kind;
+            IsInitialized = true;
         }
 
         public ITypeCompletionContext Context { get; }
 
         public RegisteredType Type { get; }
 
         public OperationType Kind { get; }
+
+        public bool IsInitialized { get; }
     }
 }

src/HotChocolate/Core/src/Types/Configuration/TypeInterceptor.cs

@@ -10,21 +10,22 @@
 
 namespace HotChocolate.Configuration;
 
+// note: this type is considered internal and should not be used by users.
 /// <summary>
 /// A type initialization interceptors can hook into the various initialization events
 /// of type system members and change / rewrite them. This is useful in order to transform
 /// specified types.
 /// </summary>
 public abstract class TypeInterceptor
 {
-    private const uint _position = uint.MaxValue / 2;
+    private const uint _defaultPosition = uint.MaxValue / 2;
 
     /// <summary>
     /// A weight to order interceptors.
     /// </summary>
-    internal virtual uint Position => _position;
+    internal virtual uint Position => _defaultPosition;
 
-    public virtual bool IsEnabled(IDescriptorContext context) => true;
+    internal virtual bool IsEnabled(IDescriptorContext context) => true;
 
     /// <summary>
     /// This hook is invoked before anything else any allows for additional modification
@@ -169,9 +170,10 @@ public virtual void OnAfterCompleteName(
 
     internal virtual void OnAfterResolveRootType(
         ITypeCompletionContext completionContext,
-        DefinitionBase definition,
-        OperationType operationType) { }
-
+        ObjectTypeDefinition definition,
+        OperationType operationType)
+    { }
+
     public virtual void OnTypesCompletedName() { }
 
     /// <summary>
@@ -183,6 +185,23 @@ public virtual void OnBeforeMergeTypeExtensions() { }
     /// This method is called after the type extensions are merged.
     /// </summary>
     public virtual void OnAfterMergeTypeExtensions() { }
+
+    internal virtual void OnBeforeCompleteMutation(
+        ITypeCompletionContext completionContext,
+        ObjectTypeDefinition definition)
+    {
+        foreach (var field in definition.Fields)
+        {
+            OnBeforeCompleteMutationField(completionContext, field);
+        }
+    }
+
+    public virtual void OnBeforeCompleteMutationField(
+        ITypeCompletionContext completionContext,
+        ObjectFieldDefinition mutationField)
+    {
+    }
+
 
     /// <summary>
     /// This method is called before the types are completed.

src/HotChocolate/Core/src/Types/HotChocolate.Types.csproj

@@ -31,6 +31,7 @@
     <InternalsVisibleTo Include="HotChocolate.Types.Filters" />
     <InternalsVisibleTo Include="HotChocolate.Types.Sorting" />
     <InternalsVisibleTo Include="HotChocolate.Types.Selections" />
+    <InternalsVisibleTo Include="HotChocolate.Stitching" />
 
     <!--Tests-->
     <InternalsVisibleTo Include="HotChocolate.Types.Filters.Tests" />

src/HotChocolate/Core/src/Types/Types/Interceptors/MiddlewareValidationTypeInterceptor.cs

@@ -177,7 +177,7 @@ void PrintOther()
 
 internal sealed class EnableTrueNullabilityTypeInterceptor : TypeInterceptor
 {
-    public override bool IsEnabled(IDescriptorContext context)
+    internal override bool IsEnabled(IDescriptorContext context)
         => context.Options.EnableTrueNullability;
 
     public override void OnBeforeCreateSchema(IDescriptorContext context, ISchemaBuilder schemaBuilder)

src/HotChocolate/Core/src/Types/Types/Introspection/IntrospectionTypeInterceptor.cs

@@ -39,12 +39,12 @@ public override void OnAfterCompleteName(
 
     internal override void OnAfterResolveRootType(
         ITypeCompletionContext completionContext,
-        DefinitionBase definition,
+        ObjectTypeDefinition definition,
         OperationType operationType)
     {
-        if (operationType is OperationType.Query && definition is ObjectTypeDefinition typeDef)
+        if (operationType is OperationType.Query)
         {
-            _queryTypeDefinition = typeDef;
+            _queryTypeDefinition = definition;
         }
     }
 

src/HotChocolate/Core/src/Types/Types/ObjectType.Initialization.cs

@@ -71,7 +71,7 @@ protected virtual FieldCollection<ObjectField> OnCompleteFields(
         ITypeCompletionContext context,
         ObjectTypeDefinition definition)
     {
-        if (context.IsMutationType ?? false)
+        if (((RegisteredType)context).IsMutationType ?? false)
         {
             // if this type represents the mutation type we flag all fields as serially executable
             // so that the operation compiler and execution engine will uphold the spec

src/HotChocolate/Core/src/Types/Types/Relay/NodeFieldTypeInterceptor.cs

@@ -27,13 +27,13 @@ internal sealed class NodeFieldTypeInterceptor : TypeInterceptor
 
     internal override void OnAfterResolveRootType(
         ITypeCompletionContext completionContext,
-        DefinitionBase definition,
+        ObjectTypeDefinition definition,
         OperationType operationType)
     {
-        if (operationType is OperationType.Query && definition is ObjectTypeDefinition typeDef)
+        if (operationType is OperationType.Query)
         {
             _queryContext = completionContext;
-            _queryTypeDefinition = typeDef;
+            _queryTypeDefinition = definition;
         }
     }
 

src/HotChocolate/Core/src/Types/Types/Relay/NodeResolverTypeInterceptor.cs

@@ -42,16 +42,15 @@ TypeDef is not null &&
 
     internal override void OnAfterResolveRootType(
         ITypeCompletionContext completionContext,
-        DefinitionBase definition,
+        ObjectTypeDefinition definition,
         OperationType operationType)
     {
         // we are only interested in the query type to infer node resolvers.
         if (operationType is OperationType.Query &&
-            definition is ObjectTypeDefinition typeDef &&
             completionContext.Type is ObjectType queryType)
         {
             CompletionContext = completionContext;
-            TypeDef = typeDef;
+            TypeDef = definition;
             QueryType = queryType;
         }
     }

src/HotChocolate/Core/src/Types/Types/Relay/QueryFieldTypeInterceptor.cs

@@ -23,7 +23,7 @@ internal sealed class QueryFieldTypeInterceptor : TypeInterceptor
 
     internal override void OnAfterResolveRootType(
         ITypeCompletionContext completionContext,
-        DefinitionBase definition,
+        ObjectTypeDefinition definition,
         OperationType operationType)
     {
         _context ??= completionContext;