diff --git a/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorBuilderExtensions.Composite.cs b/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorBuilderExtensions.Composite.cs
index 23d923d66ba..c0c17479f6d 100644
--- a/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorBuilderExtensions.Composite.cs
+++ b/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorBuilderExtensions.Composite.cs
@@ -33,6 +33,7 @@ public static IRequestExecutorBuilder AddSourceSchemaDefaults(
             o.ApplyShareableToPageInfo = true;
             o.ApplyShareableToNodeFields = true;
             o.ApplySerializeAsToScalars = true;
+            o.InferKeysFromLookups = true;
         });
     }
 }
diff --git a/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorServiceCollectionExtensions.cs b/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorServiceCollectionExtensions.cs
index e0532f05e47..919009582b6 100644
--- a/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorServiceCollectionExtensions.cs
+++ b/src/HotChocolate/Core/src/Types/Execution/DependencyInjection/RequestExecutorServiceCollectionExtensions.cs
@@ -9,6 +9,7 @@
 using HotChocolate.Fetching;
 using HotChocolate.Language;
 using HotChocolate.Resolvers;
+using HotChocolate.Types.Composite;
 using HotChocolate.Validation;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.ObjectPool;
@@ -144,6 +145,7 @@ private static DefaultRequestExecutorBuilder CreateBuilder(
 
         builder.TryAddTypeInterceptor<DataLoaderRootFieldTypeInterceptor>();
         builder.TryAddTypeInterceptor<RequirementsTypeInterceptor>();
+        builder.TryAddTypeInterceptor<SourceSchemaKeyInferenceTypeInterceptor>();
 
         builder.AddDocumentCache();
 
diff --git a/src/HotChocolate/Core/src/Types/IReadOnlySchemaOptions.cs b/src/HotChocolate/Core/src/Types/IReadOnlySchemaOptions.cs
index 27c0685c11d..ea4f5e7f812 100644
--- a/src/HotChocolate/Core/src/Types/IReadOnlySchemaOptions.cs
+++ b/src/HotChocolate/Core/src/Types/IReadOnlySchemaOptions.cs
@@ -244,4 +244,10 @@ public interface IReadOnlySchemaOptions
     /// Applies the @serializeAs directive to scalar types that specify a serialization format.
     /// </summary>
     bool ApplySerializeAsToScalars { get; }
+
+    /// <summary>
+    /// Infers @key directives from the arguments of @lookup fields so that the published
+    /// source schema describes the entity keys that the lookups resolve.
+    /// </summary>
+    bool InferKeysFromLookups { get; }
 }
diff --git a/src/HotChocolate/Core/src/Types/SchemaOptions.cs b/src/HotChocolate/Core/src/Types/SchemaOptions.cs
index f00708c0ad5..219f3dfe07c 100644
--- a/src/HotChocolate/Core/src/Types/SchemaOptions.cs
+++ b/src/HotChocolate/Core/src/Types/SchemaOptions.cs
@@ -195,6 +195,9 @@ public int OperationDocumentCacheSize
     /// <inheritdoc cref="IReadOnlySchemaOptions.ApplySerializeAsToScalars"/>
     public bool ApplySerializeAsToScalars { get; set; }
 
+    /// <inheritdoc cref="IReadOnlySchemaOptions.InferKeysFromLookups"/>
+    public bool InferKeysFromLookups { get; set; }
+
     /// <summary>
     /// Creates a mutable options object from a read-only options object.
     /// </summary>
@@ -238,6 +241,7 @@ public static SchemaOptions FromOptions(IReadOnlySchemaOptions options)
             ApplyShareableToPageInfo = options.ApplyShareableToPageInfo,
             ApplyShareableToConnections = options.ApplyShareableToConnections,
             ApplyShareableToNodeFields = options.ApplyShareableToNodeFields,
-            ApplySerializeAsToScalars = options.ApplySerializeAsToScalars
+            ApplySerializeAsToScalars = options.ApplySerializeAsToScalars,
+            InferKeysFromLookups = options.InferKeysFromLookups
         };
 }
diff --git a/src/HotChocolate/Core/src/Types/Types/Composite/Directives/EntityKey.cs b/src/HotChocolate/Core/src/Types/Types/Composite/Directives/EntityKey.cs
index 085e491f481..ab32ddd81b7 100644
--- a/src/HotChocolate/Core/src/Types/Types/Composite/Directives/EntityKey.cs
+++ b/src/HotChocolate/Core/src/Types/Types/Composite/Directives/EntityKey.cs
@@ -9,7 +9,7 @@ namespace HotChocolate.Types.Composite;
 /// an entity across different source schemas.
 /// </para>
 /// <para>
-/// directive @key(fields: FieldSelectionSet!) on OBJECT | INTERFACE
+/// directive @key(fields: FieldSelectionSet!) repeatable on OBJECT | INTERFACE
 /// </para>
 /// <para>
 /// <see href="https://graphql.github.io/composite-schemas-spec/draft/#sec--key"/>
@@ -19,7 +19,7 @@ namespace HotChocolate.Types.Composite;
     DirectiveNames.Key.Name,
     DirectiveLocation.Object
     | DirectiveLocation.Interface,
-    IsRepeatable = false)]
+    IsRepeatable = true)]
 [GraphQLDescription(
     """
     The @key directive is used to designate an entity's unique key,
diff --git a/src/HotChocolate/Core/src/Types/Types/Composite/SourceSchemaKeyInferenceTypeInterceptor.cs b/src/HotChocolate/Core/src/Types/Types/Composite/SourceSchemaKeyInferenceTypeInterceptor.cs
new file mode 100644
index 00000000000..b6617e259e8
--- /dev/null
+++ b/src/HotChocolate/Core/src/Types/Types/Composite/SourceSchemaKeyInferenceTypeInterceptor.cs
@@ -0,0 +1,496 @@
+using HotChocolate.Configuration;
+using HotChocolate.Fusion.Language;
+using HotChocolate.Fusion.Rewriters;
+using HotChocolate.Internal;
+using HotChocolate.Language;
+using HotChocolate.Types.Descriptors;
+using HotChocolate.Types.Descriptors.Configurations;
+
+namespace HotChocolate.Types.Composite;
+
+/// <summary>
+/// Infers @key directives from the arguments of @lookup fields and applies them to the
+/// types that the lookups resolve so that the published source schema describes the
+/// entity keys.
+/// </summary>
+internal sealed class SourceSchemaKeyInferenceTypeInterceptor : TypeInterceptor
+{
+    private const string IsFieldArgumentName = "field";
+
+    private readonly List<LookupInfo> _lookups = [];
+    private readonly Dictionary<string, TypeConfiguration> _typesByName = new(StringComparer.Ordinal);
+    private readonly Dictionary<string, List<TypeConfiguration>> _implementersByInterface =
+        new(StringComparer.Ordinal);
+    private readonly Dictionary<string, List<TypeConfiguration>> _membersByUnion =
+        new(StringComparer.Ordinal);
+    private ITypeCompletionContext? _completionContext;
+    private TypeReference _entityKeyRef = null!;
+
+    public override bool IsEnabled(IDescriptorContext context)
+        => context.Options.InferKeysFromLookups;
+
+    public override void OnBeforeRegisterDependencies(
+        ITypeDiscoveryContext discoveryContext,
+        TypeSystemConfiguration configuration)
+    {
+        // If a lookup is present we make sure that the @key directive type is registered,
+        // so that the inferred directive can be resolved even when no @key was declared manually.
+        if (configuration is not (ObjectTypeConfiguration or InterfaceTypeConfiguration))
+        {
+            return;
+        }
+
+        if (!HasInferableLookupField((TypeConfiguration)configuration))
+        {
+            return;
+        }
+
+        _entityKeyRef ??= discoveryContext.TypeInspector.GetTypeRef(typeof(EntityKey));
+        discoveryContext.Dependencies.Add(new TypeDependency(_entityKeyRef));
+    }
+
+    public override void OnAfterCompleteName(
+        ITypeCompletionContext completionContext,
+        TypeSystemConfiguration configuration)
+    {
+        // We capture a completion context so that we can resolve type references once all
+        // type names are completed.
+        _completionContext ??= completionContext;
+
+        switch (configuration)
+        {
+            case ObjectTypeConfiguration objectType:
+                // We only index the base type, not type extensions. Extensions are merged into the
+                // base before keys are applied, so the indexed base carries the merged directives
+                // that the deduplication relies on. Lookups declared on an extension are still
+                // collected below.
+                if (!objectType.IsExtension)
+                {
+                    _typesByName[objectType.Name] = objectType;
+                }
+                CollectLookups(objectType.Fields);
+                break;
+
+            case InterfaceTypeConfiguration interfaceType:
+                _typesByName[interfaceType.Name] = interfaceType;
+                CollectLookups(interfaceType.Fields);
+                break;
+
+            case UnionTypeConfiguration unionType:
+                _typesByName[unionType.Name] = unionType;
+                break;
+        }
+    }
+
+    public override void OnBeforeCompleteTypes()
+    {
+        if (_lookups.Count == 0 || _completionContext is null)
+        {
+            return;
+        }
+
+        var context = _completionContext;
+
+        BuildImplementerIndex(context);
+
+        foreach (var lookup in _lookups)
+        {
+            if (!context.TryGetType<IType>(lookup.ReturnTypeRef, out var returnType))
+            {
+                continue;
+            }
+
+            var namedType = returnType.NamedType();
+
+            // We only infer keys for nullable, non-list lookups, mirroring the composer.
+            if (returnType.IsNonNullType() || returnType.IsListType())
+            {
+                continue;
+            }
+
+            var targets = ResolveTargets(namedType);
+
+            if (targets.Count == 0)
+            {
+                continue;
+            }
+
+            foreach (var keyFields in BuildKeySelectionSets(lookup))
+            {
+                foreach (var target in targets)
+                {
+                    ApplyKey(context, target, keyFields);
+                }
+            }
+        }
+    }
+
+    private void CollectLookups<TField>(IEnumerable<TField> fields)
+        where TField : OutputFieldConfiguration
+    {
+        foreach (var field in fields)
+        {
+            if (field.Type is null || !HasDirective(field.GetDirectives(), DirectiveNames.Lookup.Name))
+            {
+                continue;
+            }
+
+            // We exclude lookups without arguments, mirroring the composer which cannot derive any
+            // key fields from an argument-less lookup.
+            if (!field.HasArguments)
+            {
+                continue;
+            }
+
+            _lookups.Add(new LookupInfo(field, field.Type));
+        }
+    }
+
+    private void BuildImplementerIndex(ITypeCompletionContext context)
+    {
+        foreach (var (_, configuration) in _typesByName)
+        {
+            switch (configuration)
+            {
+                // We only index object types as interface implementers, mirroring the composer's
+                // inference pass which applies inferred keys to the possible (object) types of an
+                // interface and the interface itself. Sub-interfaces are intentionally excluded.
+                case ObjectTypeConfiguration objectType:
+                    foreach (var interfaceRef in objectType.GetInterfaces())
+                    {
+                        if (context.TryGetType<IType>(interfaceRef, out var interfaceType)
+                            && interfaceType.NamedType() is IInterfaceTypeDefinition i)
+                        {
+                            AddToIndex(_implementersByInterface, i.Name, objectType);
+                        }
+                    }
+                    break;
+
+                case UnionTypeConfiguration unionType:
+                    foreach (var memberRef in unionType.Types)
+                    {
+                        if (context.TryGetType<IType>(memberRef, out var memberType)
+                            && memberType.NamedType() is IObjectTypeDefinition o
+                            && _typesByName.TryGetValue(o.Name, out var memberConfig))
+                        {
+                            AddToIndex(_membersByUnion, unionType.Name, memberConfig);
+                        }
+                    }
+                    break;
+            }
+        }
+    }
+
+    private List<TypeConfiguration> ResolveTargets(ITypeDefinition namedType)
+    {
+        var targets = new List<TypeConfiguration>();
+
+        switch (namedType)
+        {
+            case IObjectTypeDefinition objectType:
+                if (_typesByName.TryGetValue(objectType.Name, out var objectConfig))
+                {
+                    targets.Add(objectConfig);
+                }
+                break;
+
+            case IInterfaceTypeDefinition interfaceType:
+                if (_typesByName.TryGetValue(interfaceType.Name, out var interfaceConfig))
+                {
+                    targets.Add(interfaceConfig);
+                }
+
+                if (_implementersByInterface.TryGetValue(interfaceType.Name, out var implementers))
+                {
+                    targets.AddRange(implementers);
+                }
+                break;
+
+            case IUnionTypeDefinition unionType:
+                // The @key directive is only valid on OBJECT and INTERFACE, so we apply it to the
+                // members of the union and not to the union itself.
+                if (_membersByUnion.TryGetValue(unionType.Name, out var members))
+                {
+                    targets.AddRange(members);
+                }
+                break;
+        }
+
+        return targets;
+    }
+
+    private static IEnumerable<SelectionSetNode> BuildKeySelectionSets(LookupInfo lookup)
+    {
+        // We convert the @is value selections into @key selection sets purely syntactically so
+        // that the conversion does not depend on the completed type graph. This lets nested @is
+        // paths (for example "address.id") be turned into nested selection sets ("address { id }")
+        // even though the referenced child type is not yet completed at this phase. Malformed
+        // value selections are filtered out earlier while parsing, so genuine bugs surface here
+        // instead of being silently dropped.
+        foreach (var group in GetValueSelectionGroups(lookup.Field))
+        {
+            yield return ValueSelectionToSelectionSetRewriter.Rewrite(group);
+        }
+    }
+
+    private static List<List<IValueSelectionNode>> GetValueSelectionGroups(OutputFieldConfiguration field)
+    {
+        var arrays = new List<IValueSelectionNode[]>();
+
+        foreach (var argument in field.GetArguments())
+        {
+            var selectionMap = GetIsFieldSelectionMap(argument) ?? argument.Name;
+
+            IValueSelectionNode parsed;
+
+            try
+            {
+                parsed = FieldSelectionMapParser.Parse(selectionMap);
+            }
+            catch (FieldSelectionMapSyntaxException)
+            {
+                return [];
+            }
+
+            if (parsed is ChoiceValueSelectionNode choice)
+            {
+                arrays.Add([.. choice.Branches]);
+            }
+            else
+            {
+                arrays.Add([parsed]);
+            }
+        }
+
+        return GetAllCombinations(arrays);
+    }
+
+    private static string? GetIsFieldSelectionMap(ArgumentConfiguration argument)
+    {
+        foreach (var directive in argument.GetDirectives())
+        {
+            switch (directive.Value)
+            {
+                case Is @is:
+                    return @is.Field.ToString(false);
+
+                case DirectiveNode { Name.Value: DirectiveNames.Is.Name } node:
+                    var fieldArgument = node.Arguments
+                        .FirstOrDefault(a => a.Name.Value == IsFieldArgumentName);
+
+                    if (fieldArgument?.Value is StringValueNode stringValue)
+                    {
+                        return stringValue.Value;
+                    }
+                    break;
+            }
+        }
+
+        return null;
+    }
+
+    private static void ApplyKey(
+        ITypeCompletionContext context,
+        TypeConfiguration target,
+        SelectionSetNode keyFields)
+    {
+        // We deduplicate keys order-insensitively and structurally (so "id sku" equals "sku id"
+        // and "address { id }" is compared by shape). This also suppresses an inferred key when an
+        // equivalent key was declared manually, which keeps the interceptor idempotent against
+        // manually authored keys.
+        var normalizedKey = NormalizeSelectionSet(keyFields);
+
+        foreach (var directive in target.GetDirectives())
+        {
+            if (TryGetKeySelectionSet(directive.Value, out var existing)
+                && string.Equals(NormalizeSelectionSet(existing), normalizedKey, StringComparison.Ordinal))
+            {
+                return;
+            }
+        }
+
+        target.AddDirective(new EntityKey(keyFields), context.TypeInspector);
+    }
+
+    private static bool TryGetKeySelectionSet(object value, out SelectionSetNode selectionSet)
+    {
+        switch (value)
+        {
+            case EntityKey entityKey:
+                selectionSet = entityKey.Fields;
+                return true;
+
+            case DirectiveNode { Name.Value: DirectiveNames.Key.Name } node:
+                var fieldsArgument = node.Arguments
+                    .FirstOrDefault(a => a.Name.Value == DirectiveNames.Key.Arguments.Fields);
+
+                if (fieldsArgument?.Value is StringValueNode stringValue)
+                {
+                    try
+                    {
+                        selectionSet = FieldSelectionSetType.ParseSelectionSet(stringValue.Value);
+                        return true;
+                    }
+                    catch (SyntaxException)
+                    {
+                        // ignore invalid manual key syntax for deduplication purposes.
+                    }
+                }
+                break;
+        }
+
+        selectionSet = null!;
+        return false;
+    }
+
+    private static string NormalizeSelectionSet(SelectionSetNode selectionSet)
+    {
+        var entries = new List<string>();
+
+        foreach (var selection in selectionSet.Selections)
+        {
+            switch (selection)
+            {
+                case FieldNode field:
+                    var nested = field.SelectionSet is null
+                        ? string.Empty
+                        : "{" + NormalizeSelectionSet(field.SelectionSet) + "}";
+                    entries.Add(field.Name.Value + nested);
+                    break;
+
+                case InlineFragmentNode inlineFragment:
+                    var typeCondition = inlineFragment.TypeCondition?.Name.Value ?? string.Empty;
+                    entries.Add(
+                        "..." + typeCondition + "{" + NormalizeSelectionSet(inlineFragment.SelectionSet) + "}");
+                    break;
+            }
+        }
+
+        entries.Sort(StringComparer.Ordinal);
+
+        return string.Join(" ", entries);
+    }
+
+    private static bool HasInferableLookupField(TypeConfiguration type)
+    {
+        switch (type)
+        {
+            case ObjectTypeConfiguration objectType:
+                foreach (var field in objectType.Fields)
+                {
+                    if (IsInferableLookup(field))
+                    {
+                        return true;
+                    }
+                }
+                break;
+
+            case InterfaceTypeConfiguration interfaceType:
+                foreach (var field in interfaceType.Fields)
+                {
+                    if (IsInferableLookup(field))
+                    {
+                        return true;
+                    }
+                }
+                break;
+        }
+
+        return false;
+    }
+
+    // A lookup can only contribute a key when it is a @lookup field that carries arguments and
+    // resolves a nullable, non-list type, mirroring the eligibility applied while keys are built.
+    // We restrict the @key type dependency to those fields so that schemas whose lookups never
+    // produce a key are not forced to reference the inferred key's scalar.
+    private static bool IsInferableLookup(OutputFieldConfiguration field)
+    {
+        if (field.Type is null
+            || !field.HasArguments
+            || !HasDirective(field.GetDirectives(), DirectiveNames.Lookup.Name))
+        {
+            return false;
+        }
+
+        return IsNullableNonListReturnType(field.Type);
+    }
+
+    private static bool IsNullableNonListReturnType(TypeReference typeReference)
+        => typeReference switch
+        {
+            ExtendedTypeReference extended
+                => extended.Type is { IsNullable: true, IsArrayOrList: false },
+
+            SyntaxTypeReference syntax
+                => syntax.Type is not (NonNullTypeNode or ListTypeNode),
+
+            // For reference kinds whose nullability cannot be inspected at this phase we keep the
+            // dependency so that a key can still be applied later if the resolved type is eligible.
+            _ => true
+        };
+
+    private static bool HasDirective(
+        IReadOnlyList<DirectiveConfiguration> directives,
+        string name)
+    {
+        foreach (var directive in directives)
+        {
+            switch (directive.Value)
+            {
+                case Lookup when name == DirectiveNames.Lookup.Name:
+                    return true;
+
+                case DirectiveNode node when node.Name.Value == name:
+                    return true;
+            }
+        }
+
+        return false;
+    }
+
+    private static void AddToIndex(
+        Dictionary<string, List<TypeConfiguration>> index,
+        string key,
+        TypeConfiguration value)
+    {
+        if (!index.TryGetValue(key, out var list))
+        {
+            list = [];
+            index[key] = list;
+        }
+
+        list.Add(value);
+    }
+
+    private static List<List<T>> GetAllCombinations<T>(List<T[]> arrays)
+    {
+        if (arrays.Count == 0)
+        {
+            return [[]];
+        }
+
+        var result = new List<List<T>> { new() };
+
+        foreach (var array in arrays)
+        {
+            var temp = new List<List<T>>();
+
+            foreach (var item in array)
+            {
+                foreach (var combination in result)
+                {
+                    var newCombination = new List<T>(combination) { item };
+                    temp.Add(newCombination);
+                }
+            }
+
+            result = temp;
+        }
+
+        return result;
+    }
+
+    private readonly record struct LookupInfo(
+        OutputFieldConfiguration Field,
+        TypeReference ReturnTypeRef);
+}
diff --git a/src/HotChocolate/Core/test/Types.Tests/Types/Composite/LookupTests.cs b/src/HotChocolate/Core/test/Types.Tests/Types/Composite/LookupTests.cs
index c19ab713d43..c509298e1fa 100644
--- a/src/HotChocolate/Core/test/Types.Tests/Types/Composite/LookupTests.cs
+++ b/src/HotChocolate/Core/test/Types.Tests/Types/Composite/LookupTests.cs
@@ -120,7 +120,7 @@ directive @is("The field selection map syntax." field: FieldSelectionMap!) on
             which identifies how to uniquely reference an instance of
             an entity across different source schemas.
             """
-            directive @key("The field selection set syntax." fields: FieldSelectionSet!) on
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
               | OBJECT
               | INTERFACE
 
@@ -179,7 +179,7 @@ directive @is("The field selection map syntax." field: FieldSelectionMap!) on
             which identifies how to uniquely reference an instance of
             an entity across different source schemas.
             """
-            directive @key("The field selection set syntax." fields: FieldSelectionSet!) on
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
               | OBJECT
               | INTERFACE
 
diff --git a/src/HotChocolate/Core/test/Types.Tests/Types/Composite/SourceSchemaKeyInferenceTests.cs b/src/HotChocolate/Core/test/Types.Tests/Types/Composite/SourceSchemaKeyInferenceTests.cs
new file mode 100644
index 00000000000..2b57b6b01d8
--- /dev/null
+++ b/src/HotChocolate/Core/test/Types.Tests/Types/Composite/SourceSchemaKeyInferenceTests.cs
@@ -0,0 +1,689 @@
+using HotChocolate.Execution;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace HotChocolate.Types.Composite;
+
+public static class SourceSchemaKeyInferenceTests
+{
+    [Fact]
+    public static async Task InferKey_Should_AddKeyToObject_When_LookupReturnsObject()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<ObjectQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: ObjectQuery
+            }
+
+            type ObjectQuery {
+              productById(id: Int!): Product @lookup
+            }
+
+            type Product @key(fields: "id") {
+              id: Int!
+              name: String!
+            }
+
+            scalar FieldSelectionSet
+
+            """
+            The @key directive is used to designate an entity's unique key,
+            which identifies how to uniquely reference an instance of
+            an entity across different source schemas.
+            """
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+              | OBJECT
+              | INTERFACE
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddKeyToInterfaceAndImplementers_When_LookupReturnsInterface()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<InterfaceQuery>()
+                .AddType<Article>()
+                .AddType<Video>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: InterfaceQuery
+            }
+
+            type InterfaceQuery {
+              contentById(id: Int!): Content @lookup
+            }
+
+            type Article implements Content @key(fields: "id") {
+              id: Int!
+              body: String!
+            }
+
+            type Video implements Content @key(fields: "id") {
+              id: Int!
+              duration: Int!
+            }
+
+            interface Content @key(fields: "id") {
+              id: Int!
+            }
+
+            scalar FieldSelectionSet
+
+            """
+            The @key directive is used to designate an entity's unique key,
+            which identifies how to uniquely reference an instance of
+            an entity across different source schemas.
+            """
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+              | OBJECT
+              | INTERFACE
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddKeyToMembersNotUnion_When_LookupReturnsUnion()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<UnionQuery>()
+                .AddType<Cat>()
+                .AddType<Dog>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: UnionQuery
+            }
+
+            type UnionQuery {
+              petById(id: Int!): Pet @lookup
+            }
+
+            type Cat @key(fields: "id") {
+              id: Int!
+              meows: Boolean!
+            }
+
+            type Dog @key(fields: "id") {
+              id: Int!
+              barks: Boolean!
+            }
+
+            union Pet = Cat | Dog
+
+            scalar FieldSelectionSet
+
+            """
+            The @key directive is used to designate an entity's unique key,
+            which identifies how to uniquely reference an instance of
+            an entity across different source schemas.
+            """
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+              | OBJECT
+              | INTERFACE
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_NotDuplicate_When_DeveloperDeclaredKey()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<DeclaredKeyQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: DeclaredKeyQuery
+            }
+
+            type DeclaredKeyQuery {
+              userById(id: Int!): User @lookup
+            }
+
+            type User @key(fields: "id") {
+              id: Int!
+              name: String!
+            }
+
+            scalar FieldSelectionSet
+
+            """
+            The @key directive is used to designate an entity's unique key,
+            which identifies how to uniquely reference an instance of
+            an entity across different source schemas.
+            """
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+              | OBJECT
+              | INTERFACE
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddTwoKeys_When_ChoiceIsArgument()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<ChoiceQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: ChoiceQuery
+            }
+
+            type ChoiceQuery {
+              accountBy(by: AccountByInput! @is(field: "{\n  id\n} | {\n  email\n}")): Account
+                @lookup
+            }
+
+            type Account @key(fields: "id") @key(fields: "email") {
+              id: Int!
+              email: String!
+            }
+
+            input AccountByInput @oneOf {
+              id: Int
+              email: String
+            }
+
+            scalar FieldSelectionMap
+
+            scalar FieldSelectionSet
+
+            """
+            The @is directive is utilized on lookup fields to describe how the arguments
+            can be mapped from the entity type that the lookup field resolves.
+            """
+            directive @is("The field selection map syntax." field: FieldSelectionMap!) on
+              | ARGUMENT_DEFINITION
+
+            """
+            The @key directive is used to designate an entity's unique key,
+            which identifies how to uniquely reference an instance of
+            an entity across different source schemas.
+            """
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+              | OBJECT
+              | INTERFACE
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddThreeDistinctKeys_When_ChoiceIsHasNestedPath()
+    {
+        // arrange & act
+        // composite-schemas spec example #4214e
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<NestedChoiceQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: NestedChoiceQuery
+            }
+
+            type NestedChoiceQuery {
+              person(
+                by: PersonByInput! @is(field: "{\n  id\n} | {\n  addressId: address.id\n} | {\n  name\n}")
+              ): Person @lookup
+            }
+
+            type Address {
+              id: Int!
+            }
+
+            type Person
+              @key(fields: "id")
+              @key(fields: "address { id }")
+              @key(fields: "name") {
+              id: Int!
+              name: String!
+              address: Address!
+            }
+
+            input PersonByInput @oneOf {
+              id: Int
+              addressId: Int
+              name: String
+            }
+
+            scalar FieldSelectionMap
+
+            scalar FieldSelectionSet
+
+            """
+            The @is directive is utilized on lookup fields to describe how the arguments
+            can be mapped from the entity type that the lookup field resolves.
+            """
+            directive @is("The field selection map syntax." field: FieldSelectionMap!) on
+              | ARGUMENT_DEFINITION
+
+            """
+            The @key directive is used to designate an entity's unique key,
+            which identifies how to uniquely reference an instance of
+            an entity across different source schemas.
+            """
+            directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+              | OBJECT
+              | INTERFACE
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddNestedKey_When_IsPathIsNested()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<NestedPathQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var person = schema.Types.GetType<IObjectTypeDefinition>("Person");
+        var keys = person.Directives.Where(d => d.Name == "key").ToArray();
+        Assert.Equal(@"@key(fields: ""address { id }"")", Assert.Single(keys).ToString());
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_MergeArgumentsInDeclarationOrder_When_LookupHasMultipleArguments()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<MultiArgQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var product = schema.Types.GetType<IObjectTypeDefinition>("Product");
+        var keys = product.Directives.Where(d => d.Name == "key").ToArray();
+        Assert.Equal(@"@key(fields: ""id categoryId"")", Assert.Single(keys).ToString());
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_NotDuplicate_When_DeveloperDeclaredKeyInReverseOrder()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<ReverseKeyQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var part = schema.Types.GetType<IObjectTypeDefinition>("Part");
+        var keys = part.Directives.Where(d => d.Name == "key").ToArray();
+        Assert.Equal(@"@key(fields: ""sku id"")", Assert.Single(keys).ToString());
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddTwoDistinctKeys_When_MultipleLookupsReturnSameType()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<TwoLookupsQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var book = schema.Types.GetType<IObjectTypeDefinition>("Book");
+        var keys = book.Directives
+            .Where(d => d.Name == "key")
+            .Select(d => d.ToString())
+            .OrderBy(s => s, StringComparer.Ordinal)
+            .ToArray();
+        string[] expected = [@"@key(fields: ""id"")", @"@key(fields: ""isbn"")"];
+        Assert.Equal(expected, keys);
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddKey_When_SourceSchemaDefaultsEnabled()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<ObjectQuery>()
+                .AddSourceSchemaDefaults()
+                .BuildSchemaAsync();
+
+        // assert
+        var product = schema.Types.GetType<IObjectTypeDefinition>("Product");
+        var keys = product.Directives.Where(d => d.Name == "key").ToArray();
+        Assert.Equal(@"@key(fields: ""id"")", Assert.Single(keys).ToString());
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_NotInferKey_When_DefaultOptionsAndNoSourceSchemaDefaults()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<ObjectQuery>()
+                .BuildSchemaAsync();
+
+        // assert
+        var product = schema.Types.GetType<IObjectTypeDefinition>("Product");
+        Assert.DoesNotContain(product.Directives, d => d.Name == "key");
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddCompositeKey_When_LookupHasMultipleArguments_WithNullableArg()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<NullableMultiArgQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var product = schema.Types.GetType<IObjectTypeDefinition>("Product");
+        var keys = product.Directives.Where(d => d.Name == "key").ToArray();
+        Assert.Equal(@"@key(fields: ""a b"")", Assert.Single(keys).ToString());
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_MergeNameAndIsMappedArguments_When_LookupHasMixedArguments()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<MixedIsQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var product = schema.Types.GetType<IObjectTypeDefinition>("Product");
+        var keys = product.Directives.Where(d => d.Name == "key").ToArray();
+        Assert.Equal(@"@key(fields: ""a c"")", Assert.Single(keys).ToString());
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_AddCartesianKeys_When_PlainArgCombinedWithChoiceIs()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<CartesianQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = true)
+                .BuildSchemaAsync();
+
+        // assert
+        var account = schema.Types.GetType<IObjectTypeDefinition>("Account");
+        var keys = account.Directives
+            .Where(d => d.Name == "key")
+            .Select(d => d.ToString())
+            .ToArray();
+        string[] expected = [@"@key(fields: ""tenant id"")", @"@key(fields: ""tenant email"")"];
+        Assert.Equal(expected, keys);
+    }
+
+    [Fact]
+    public static async Task InferKey_Should_NotAddKey_When_OptedOut()
+    {
+        // arrange & act
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType<ObjectQuery>()
+                .ModifyOptions(o => o.InferKeysFromLookups = false)
+                .BuildSchemaAsync();
+
+        // assert
+        schema.MatchInlineSnapshot(
+            """"
+            schema {
+              query: ObjectQuery
+            }
+
+            type ObjectQuery {
+              productById(id: Int!): Product @lookup
+            }
+
+            type Product {
+              id: Int!
+              name: String!
+            }
+
+            """
+            The @lookup directive is used within a source schema to specify output fields
+            that can be used by the distributed GraphQL executor to resolve an entity by
+            a stable key.
+            """
+            directive @lookup on FIELD_DEFINITION
+            """");
+    }
+
+    public class ObjectQuery
+    {
+        [Lookup]
+        public Product? GetProductById(int id)
+            => new(id, "Abc");
+    }
+
+    public record Product(int Id, string Name);
+
+    public class InterfaceQuery
+    {
+        [Lookup]
+        public Content? GetContentById(int id)
+            => null;
+    }
+
+    [InterfaceType]
+    public interface Content
+    {
+        int Id { get; }
+    }
+
+    public record Article(int Id, string Body) : Content;
+
+    public record Video(int Id, int Duration) : Content;
+
+    public class UnionQuery
+    {
+        [Lookup]
+        public IPet? GetPetById(int id)
+            => null;
+    }
+
+    [UnionType("Pet")]
+    public interface IPet;
+
+    public record Cat(int Id, bool Meows) : IPet;
+
+    public record Dog(int Id, bool Barks) : IPet;
+
+    public class DeclaredKeyQuery
+    {
+        [Lookup]
+        public User? GetUserById(int id)
+            => new(id, "Abc");
+    }
+
+    [EntityKey("id")]
+    public record User(int Id, string Name);
+
+    public class ChoiceQuery
+    {
+        [Lookup]
+        public Account? GetAccountBy([Is("{ id } | { email }")] AccountByInput by)
+            => new(by.Id ?? 1, by.Email ?? "abc");
+    }
+
+    [OneOf]
+    public record AccountByInput(int? Id, string? Email);
+
+    public record Account(int Id, string Email);
+
+    public class NestedChoiceQuery
+    {
+        [Lookup]
+        public Person? GetPerson(
+            [Is("{ id } | { addressId: address.id } | { name }")] PersonByInput by)
+            => null;
+    }
+
+    [OneOf]
+    public record PersonByInput(int? Id, int? AddressId, string? Name);
+
+    public record Person(int Id, string Name, Address Address);
+
+    public record Address(int Id);
+
+    public class NestedPathQuery
+    {
+        [Lookup]
+        public Person? GetPersonByAddressId([Is("address.id")] int addressId)
+            => null;
+    }
+
+    public class MultiArgQuery
+    {
+        [Lookup]
+        public Product? GetProductByIdAndCategoryId(int id, int categoryId)
+            => new(id, "Abc");
+    }
+
+    public class ReverseKeyQuery
+    {
+        [Lookup]
+        public Part? GetPartBySkuAndId(string sku, int id)
+            => null;
+    }
+
+    [EntityKey("sku id")]
+    public record Part(int Id, string Sku);
+
+    public class TwoLookupsQuery
+    {
+        [Lookup]
+        public Book? GetBookById(int id)
+            => null;
+
+        [Lookup]
+        public Book? GetBookByIsbn(string isbn)
+            => null;
+    }
+
+    public record Book(int Id, string Isbn);
+
+    public class NullableMultiArgQuery
+    {
+        [Lookup]
+        public CompositeProduct? GetProductByName(string a, string? b)
+            => null;
+    }
+
+    public class MixedIsQuery
+    {
+        [Lookup]
+        public CompositeProduct? GetProductBy(string a, [Is("c")] string b)
+            => null;
+    }
+
+    [GraphQLName("Product")]
+    public record CompositeProduct(string A, string B, string C);
+
+    public class CartesianQuery
+    {
+        [Lookup]
+        public TenantAccount? GetAccountBy(
+            string tenant,
+            [Is("{ id } | { email }")] AccountByInput by)
+            => null;
+    }
+
+    [GraphQLName("Account")]
+    public record TenantAccount(int Id, string Email, string Tenant);
+}
diff --git a/src/HotChocolate/Data/test/Data.PostgreSQL.Tests/__snapshots__/IntegrationTests.CreateSchema.graphql b/src/HotChocolate/Data/test/Data.PostgreSQL.Tests/__snapshots__/IntegrationTests.CreateSchema.graphql
index 117b368f159..c03573aa5bb 100644
--- a/src/HotChocolate/Data/test/Data.PostgreSQL.Tests/__snapshots__/IntegrationTests.CreateSchema.graphql
+++ b/src/HotChocolate/Data/test/Data.PostgreSQL.Tests/__snapshots__/IntegrationTests.CreateSchema.graphql
@@ -101,7 +101,7 @@ type BillingStatementTransaction implements StatementTransaction {
   id: Int!
 }
 
-type Brand implements Node {
+type Brand implements Node @key(fields: "id") {
   products(
     "Returns the first _n_ elements from the list."
     first: Int
@@ -222,7 +222,7 @@ type PageInfo @shareable {
   backwardCursors: [PageCursor!]!
 }
 
-type Product implements Node {
+type Product implements Node @key(fields: "id") {
   id: ID!
   brand: Brand @cost(weight: "10")
   brandName: String
@@ -439,6 +439,8 @@ scalar Decimal
   @serializeAs(type: FLOAT)
   @specifiedBy(url: "https://scalars.graphql.org/chillicream/decimal.html")
 
+scalar FieldSelectionSet
+
 "The `UnsignedByte` scalar type represents an unsigned 8-bit integer."
 scalar UnsignedByte
   @serializeAs(type: INT)
@@ -479,6 +481,15 @@ directive @internal on OBJECT | FIELD_DEFINITION
 """
 directive @internal on OBJECT | FIELD_DEFINITION
 
+"""
+The @key directive is used to designate an entity's unique key,
+which identifies how to uniquely reference an instance of
+an entity across different source schemas.
+"""
+directive @key("The field selection set syntax." fields: FieldSelectionSet!) repeatable on
+  | OBJECT
+  | INTERFACE
+
 "The purpose of the `@listSize` directive is to either inform the static analysis about the size of returned lists (if that information is statically available), or to point the analysis to where to find that information."
 directive @listSize(
   "The `assumedSize` argument can be used to statically define the maximum length of a list returned by a field."
diff --git a/src/HotChocolate/Fusion/src/Fusion.Utilities/Rewriters/ValueSelectionToSelectionSetRewriter.cs b/src/HotChocolate/Fusion/src/Fusion.Utilities/Rewriters/ValueSelectionToSelectionSetRewriter.cs
index e0f5e7b4e46..57e3d894583 100644
--- a/src/HotChocolate/Fusion/src/Fusion.Utilities/Rewriters/ValueSelectionToSelectionSetRewriter.cs
+++ b/src/HotChocolate/Fusion/src/Fusion.Utilities/Rewriters/ValueSelectionToSelectionSetRewriter.cs
@@ -39,6 +39,49 @@ public SelectionSetNode Rewrite(IEnumerable<IValueSelectionNode> nodes, ITypeDef
         return _mergeSelectionSetRewriter.Merge([new SelectionSetNode(selections)], type);
     }
 
+    /// <summary>
+    /// Turns the value selections into a single selection set without using a schema, so it can
+    /// run before the schema is built. Unlike the schema-based overloads, it does not merge or
+    /// remove duplicate selections.
+    /// </summary>
+    /// <param name="nodes">
+    /// The value selections to convert.
+    /// </param>
+    /// <returns>
+    /// A selection set that represents the given value selections.
+    /// </returns>
+    public static SelectionSetNode Rewrite(IEnumerable<IValueSelectionNode> nodes)
+    {
+        ArgumentNullException.ThrowIfNull(nodes);
+
+        var selections = new List<ISelectionNode>();
+
+        foreach (var node in nodes)
+        {
+            Flatten(Visit(node), selections);
+        }
+
+        return new SelectionSetNode(selections);
+    }
+
+    private static void Flatten(ISelectionNode selection, List<ISelectionNode> selections)
+    {
+        // An inline fragment without a type condition only groups selections, so we inline its
+        // members to keep the resulting selection list flat. Type-conditioned inline fragments and
+        // fields are preserved as-is.
+        if (selection is InlineFragmentNode { TypeCondition: null } inlineFragment)
+        {
+            foreach (var inner in inlineFragment.SelectionSet.Selections)
+            {
+                Flatten(inner, selections);
+            }
+
+            return;
+        }
+
+        selections.Add(selection);
+    }
+
     private static ISelectionNode Visit(IValueSelectionNode node)
     {
         switch (node)
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type.yaml
index ceaa64d8b03..ecb716a4234 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type.yaml
@@ -46,7 +46,7 @@ sourceSchemas:
         authorById(id: Int!): Author @lookup
       }
 
-      type Author implements SharedType {
+      type Author implements SharedType @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_Direct_Source_Schema_Call.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_Direct_Source_Schema_Call.yaml
index 60890d2c584..3f52331ff8d 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_Direct_Source_Schema_Call.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_Direct_Source_Schema_Call.yaml
@@ -55,7 +55,7 @@ sourceSchemas:
         authorById(id: Int!): Author @lookup
       }
 
-      type Author implements SharedType {
+      type Author implements SharedType @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Abstract_Lookup.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Abstract_Lookup.yaml
index c37fbd4c8da..eefe4b76aec 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Abstract_Lookup.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Abstract_Lookup.yaml
@@ -45,7 +45,7 @@ sourceSchemas:
         authorById(id: Int!): Author @lookup
       }
 
-      type Author implements SharedType {
+      type Author implements SharedType @key(fields: "id") {
         id: Int!
         name: String!
       }
@@ -129,17 +129,17 @@ sourceSchemas:
         discussionById(id: ID!): Discussion @lookup @internal
       }
 
-      type Author implements OtherInterface {
+      type Author implements OtherInterface @key(fields: "id") {
         id: Int!
         age: Int!
       }
 
-      type Discussion {
+      type Discussion @key(fields: "id") {
         id: Int!
         commentCount: Int!
       }
 
-      interface OtherInterface {
+      interface OtherInterface @key(fields: "id") {
         id: Int!
       }
     interactions:
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Concrete_Lookup.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Concrete_Lookup.yaml
index b2d57177142..ccd3ceaa52a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Concrete_Lookup.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_With_Concrete_Lookup.yaml
@@ -45,7 +45,7 @@ sourceSchemas:
         authorById(id: Int!): Author @lookup
       }
 
-      type Author implements SharedType {
+      type Author implements SharedType @key(fields: "id") {
         id: Int!
         name: String!
       }
@@ -129,17 +129,17 @@ sourceSchemas:
         discussionById(id: ID!): Discussion @lookup @internal
       }
 
-      type Author implements OtherInterface {
+      type Author implements OtherInterface @key(fields: "id") {
         id: Int!
         age: Int!
       }
 
-      type Discussion {
+      type Discussion @key(fields: "id") {
         id: Int!
         commentCount: Int!
       }
 
-      interface OtherInterface {
+      interface OtherInterface @key(fields: "id") {
         id: Int!
       }
     interactions:
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Concrete_Type_With_Abstract_Lookup.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Concrete_Type_With_Abstract_Lookup.yaml
index 610cbc6ee07..893e99bd74c 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Concrete_Type_With_Abstract_Lookup.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Concrete_Type_With_Abstract_Lookup.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         authorById(id: Int!): Author @lookup
       }
 
-      type Author implements SharedType {
+      type Author implements SharedType @key(fields: "id") {
         id: Int!
         name: String!
       }
@@ -120,17 +120,17 @@ sourceSchemas:
         discussionById(id: ID!): Discussion @lookup @internal
       }
 
-      type Author implements OtherInterface {
+      type Author implements OtherInterface @key(fields: "id") {
         id: Int!
         age: Int!
       }
 
-      type Discussion {
+      type Discussion @key(fields: "id") {
         id: Int!
         commentCount: Int!
       }
 
-      interface OtherInterface {
+      interface OtherInterface @key(fields: "id") {
         id: Int!
       }
     interactions:
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.List_Of_Abstract_Types.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.List_Of_Abstract_Types.yaml
index 3341591cce2..77890b6a0e7 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.List_Of_Abstract_Types.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.List_Of_Abstract_Types.yaml
@@ -55,7 +55,7 @@ sourceSchemas:
         authorById(id: Int!): Author @lookup
       }
 
-      type Author implements SharedType {
+      type Author implements SharedType @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Literals_Can_Be_Empty.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Literals_Can_Be_Empty.yaml
index 7f4b54e3764..306f1eb967e 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Literals_Can_Be_Empty.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Literals_Can_Be_Empty.yaml
@@ -37,7 +37,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -108,7 +108,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -132,7 +132,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Variables_Can_Be_Empty.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Variables_Can_Be_Empty.yaml
index 7dc13c9f46d..915bd4cd307 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Variables_Can_Be_Empty.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Ensure_String_Variables_Can_Be_Empty.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -116,7 +116,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -140,7 +140,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1.yaml
index bbc9b24d842..dac29f5683e 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1.yaml
@@ -43,7 +43,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -120,7 +120,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -144,7 +144,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_And_Author_From_SourceSchema2.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_And_Author_From_SourceSchema2.yaml
index d37c83cb5f7..cc5eff5a9b4 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_And_Author_From_SourceSchema2.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_And_Author_From_SourceSchema2.yaml
@@ -47,7 +47,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -128,7 +128,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -152,7 +152,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_Two_Requests.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_Two_Requests.yaml
index ad20d5e87d7..a36773a80fa 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_Two_Requests.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_Two_Requests.yaml
@@ -43,7 +43,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -120,7 +120,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -144,7 +144,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_With_Settings.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_With_Settings.yaml
index 2e047d4486b..f33ee1eefd3 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_With_Settings.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Book_From_SourceSchema1_With_Settings.yaml
@@ -43,7 +43,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -99,7 +99,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -123,7 +123,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_From_SourceSchema1_And_Authors_From_SourceSchema2.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_From_SourceSchema1_And_Authors_From_SourceSchema2.yaml
index e2ba10d4d88..da79690c288 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_From_SourceSchema1_And_Authors_From_SourceSchema2.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_From_SourceSchema1_And_Authors_From_SourceSchema2.yaml
@@ -76,7 +76,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -186,7 +186,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -210,7 +210,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1.yaml
index 7c5a0f94f6f..bc62d8d29dc 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1.yaml
@@ -56,7 +56,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -151,7 +151,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -175,7 +175,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_Three_Times.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_Three_Times.yaml
index c3bfe4b8e1b..d877e59dcda 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_Three_Times.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_Three_Times.yaml
@@ -56,7 +56,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -151,7 +151,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -175,7 +175,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_X_Times.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_X_Times.yaml
index 21f5cafcaa2..efd2d6e946b 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_X_Times.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Requirements_To_SourceSchema1_X_Times.yaml
@@ -56,7 +56,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -151,7 +151,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -175,7 +175,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Is_1.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Is_1.yaml
index de694979b02..1342d46f473 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Is_1.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Is_1.yaml
@@ -59,7 +59,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -152,7 +152,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -176,7 +176,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Omitted.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Omitted.yaml
index 1b57065f51f..713f7c896e9 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Omitted.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_And_First_Omitted.yaml
@@ -78,7 +78,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -190,7 +190,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -214,7 +214,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_Last_And_First_1_And_Last_Omitted.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_Last_And_First_1_And_Last_Omitted.yaml
index 42c890de5d3..537ea5a86d1 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_Last_And_First_1_And_Last_Omitted.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/BookStoreTests.Fetch_Books_With_Variable_First_Last_And_First_1_And_Last_Omitted.yaml
@@ -59,7 +59,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -152,7 +152,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
@@ -176,7 +176,7 @@ sourceSchemas:
         node: Author!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         idAndTitle(title: String! @require(field: "title")): String!
         id: Int!
         author: Author! @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Accessible_Value_Is_Used.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Accessible_Value_Is_Used.yaml
index e44e9a83663..78d417c2f17 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Accessible_Value_Is_Used.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Accessible_Value_Is_Used.yaml
@@ -28,7 +28,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -45,7 +45,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Inaccessible_Value_Is_Used.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Inaccessible_Value_Is_Used.yaml
index cd8dca4f1af..3c035c1adb6 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Inaccessible_Value_Is_Used.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Enum_With_Inaccessible_Value_When_Inaccessible_Value_Is_Used.yaml
@@ -45,7 +45,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -62,7 +62,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Can_Be_Queried.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Can_Be_Queried.yaml
index 9b2d86657b1..755ca7df912 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Can_Be_Queried.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Can_Be_Queried.yaml
@@ -28,7 +28,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -60,7 +60,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Cannot_Be_Passed_In.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Cannot_Be_Passed_In.yaml
index 6a5fbe228c1..a13c6059082 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Cannot_Be_Passed_In.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Field_With_Inaccessible_Argument_Cannot_Be_Passed_In.yaml
@@ -42,7 +42,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -59,7 +59,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Argument_Not_In_Field_Introspection.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Argument_Not_In_Field_Introspection.yaml
index 8c7cd9236cf..1e6b4962a4d 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Argument_Not_In_Field_Introspection.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Argument_Not_In_Field_Introspection.yaml
@@ -70,7 +70,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -87,7 +87,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Enum_Value_Not_In_Enum_Introspection.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Enum_Value_Not_In_Enum_Introspection.yaml
index 81b64ff34ec..1d4ec509b21 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Enum_Value_Not_In_Enum_Introspection.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Enum_Value_Not_In_Enum_Introspection.yaml
@@ -38,7 +38,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -55,7 +55,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Can_Be_Used_As_Requirements.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Can_Be_Used_As_Requirements.yaml
index 79b0e4a0343..24fea06ee26 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Can_Be_Used_As_Requirements.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Can_Be_Used_As_Requirements.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -76,7 +76,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried.yaml
index 02615537a03..3e6dc9ea32b 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried.yaml
@@ -46,7 +46,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -63,7 +63,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried_Via_Introspection.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried_Via_Introspection.yaml
index 435a3b1b7c0..60615417249 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried_Via_Introspection.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Fields_Cannot_Be_Queried_Via_Introspection.yaml
@@ -38,7 +38,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -55,7 +55,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Input_Field_Not_In_Input_Object_Introspection.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Input_Field_Not_In_Input_Object_Introspection.yaml
index f9ee8f2e877..825db41abed 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Input_Field_Not_In_Input_Object_Introspection.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Inaccessible_Input_Field_Not_In_Input_Object_Introspection.yaml
@@ -38,7 +38,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -55,7 +55,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Accessible_Field_Is_Passed.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Accessible_Field_Is_Passed.yaml
index 2ccfee2f163..2fdf2fc6b88 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Accessible_Field_Is_Passed.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Accessible_Field_Is_Passed.yaml
@@ -28,7 +28,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -45,7 +45,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Inaccessible_Field_Is_Not_Passed.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Inaccessible_Field_Is_Not_Passed.yaml
index f973f282aed..f20de4492f4 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Inaccessible_Field_Is_Not_Passed.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/InaccessibleTests.Input_With_Inaccessible_Field_When_Inaccessible_Field_Is_Not_Passed.yaml
@@ -43,7 +43,7 @@ sourceSchemas:
         id: Int! @inaccessible
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -60,7 +60,7 @@ sourceSchemas:
         shareable(input: SomeInput!): String!
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: Int!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Schema_Types_Name.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Schema_Types_Name.yaml
index 3ebf3b0c988..dbab4fe641a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Schema_Types_Name.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Schema_Types_Name.yaml
@@ -109,7 +109,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -164,7 +164,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Specific_Type.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Specific_Type.yaml
index aa196e40b52..ad92d58b231 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Specific_Type.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Fetch_Specific_Type.yaml
@@ -40,7 +40,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -95,7 +95,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object.yaml
index fe2b3cb1322..952f4e616a2 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object.yaml
@@ -55,7 +55,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -144,7 +144,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object_With_Alias.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object_With_Alias.yaml
index 95539114c23..0587103dead 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object_With_Alias.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Object_With_Alias.yaml
@@ -55,7 +55,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -144,7 +144,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query.yaml
index 928def3b3e0..1e34bba8ad3 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -91,7 +91,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_False.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_False.yaml
index 5412aca8838..12725ba19b6 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_False.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_False.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -91,7 +91,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_True.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_True.yaml
index f999a406872..8e88ff81df8 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_True.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_Skip_True.yaml
@@ -34,7 +34,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -89,7 +89,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_With_Alias.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_With_Alias.yaml
index c93b0b0144e..277fa471d6a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_With_Alias.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/IntrospectionTests.Typename_On_Query_With_Alias.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author! @shareable
@@ -91,7 +91,7 @@ sourceSchemas:
         ): AuthorsConnection
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         books: [Book!]!
         id: Int!
         name: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_From_Nested_Internal_Lookup.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_From_Nested_Internal_Lookup.yaml
index 55f82bc63ae..2c46baa480c 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_From_Nested_Internal_Lookup.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_From_Nested_Internal_Lookup.yaml
@@ -106,7 +106,7 @@ sourceSchemas:
         lookups: InternalLookups! @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Id.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Id.yaml
index efec5d891aa..6a3b83acfc8 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Id.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Id.yaml
@@ -111,7 +111,7 @@ sourceSchemas:
         lookups: InternalLookups! @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") @key(fields: "name") {
         id: ID!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Name.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Name.yaml
index dc1e6abcc3d..9c3cf9ff605 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Name.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/LookupTests.Fetch_OneOf_Lookup_With_Name.yaml
@@ -47,7 +47,7 @@ sourceSchemas:
         lookups: InternalLookups! @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") @key(fields: "name") {
         id: ID!
         name: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Multiple_Mutation.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Multiple_Mutation.yaml
index 64750091acc..22aa113515a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Multiple_Mutation.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Multiple_Mutation.yaml
@@ -120,7 +120,7 @@ sourceSchemas:
         bookById(id: Int!): Book @internal @lookup
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         author: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Single_Mutation.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Single_Mutation.yaml
index 17a865c2fb4..085e4b56149 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Single_Mutation.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/MutationTests.Single_Mutation.yaml
@@ -82,7 +82,7 @@ sourceSchemas:
         bookById(id: Int!): Book @internal @lookup
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         author: String!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Enumerable_In_List.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Enumerable_In_List.yaml
index 1ddd376d820..e90de55df64 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Enumerable_In_List.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Enumerable_In_List.yaml
@@ -76,7 +76,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -169,7 +169,7 @@ sourceSchemas:
         book(id: Int!): Book @lookup @shareable
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         dimension: BookDimension!
       }
@@ -188,7 +188,7 @@ sourceSchemas:
         book(id: Int!): Book @lookup @shareable
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         estimatedDelivery(
           dimension: BookDimensionInput! @require(field: "{\n  title\n  width: dimension.width\n  height: dimension.height\n}")
         ): Int!
@@ -210,7 +210,7 @@ sourceSchemas:
         book(id: Int!): Book @lookup @shareable
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         genres(genreIds: [Int!]! @require(field: "genreIds")): [Genre!]!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Object_In_A_List.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Object_In_A_List.yaml
index 2ee80e3c339..7013aeb20b1 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Object_In_A_List.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Require_Object_In_A_List.yaml
@@ -56,7 +56,7 @@ sourceSchemas:
         id: Int!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
         author: Author!
@@ -137,7 +137,7 @@ sourceSchemas:
         book(id: Int!): Book @lookup @shareable
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         dimension: BookDimension!
       }
@@ -216,7 +216,7 @@ sourceSchemas:
         book(id: Int!): Book @lookup @shareable
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         estimatedDelivery(
           dimension: BookDimensionInput! @require(field: "{\n  title\n  width: dimension.width\n  height: dimension.height\n}")
         ): Int!
@@ -304,7 +304,7 @@ sourceSchemas:
         book(id: Int!): Book @lookup @shareable
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         genres(genreIds: [Int!]! @require(field: "genreIds")): [Genre!]!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Leaf_Field.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Leaf_Field.yaml
index 2c929c4ddc9..f3811acc356 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Leaf_Field.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Leaf_Field.yaml
@@ -84,7 +84,7 @@ sourceSchemas:
         productById(id: ID!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         fieldWithNullableRequirement(
           nullableArgument: String @require(field: "nullableField")
         ): String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Nullable_Leaf_Field_Returning_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Nullable_Leaf_Field_Returning_Null.yaml
index cf612aee360..230747d6de3 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Nullable_Leaf_Field_Returning_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Nullable_Leaf_Field_Returning_Null.yaml
@@ -84,7 +84,7 @@ sourceSchemas:
         productById(id: ID!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         fieldWithNullableRequirement(
           nullableArgument: String @require(field: "nullableField")
         ): String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object.yaml
index b13836a70b7..037563c841c 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object.yaml
@@ -92,7 +92,7 @@ sourceSchemas:
         productById(id: ID!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         fieldWithNullableRequirement(
           nullableArgument: String @require(field: "nullableObject.field")
         ): String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object_Returning_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object_Returning_Null.yaml
index 974d68c5d79..81a612543ad 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object_Returning_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/RequireTests.Requirement_On_Property_Within_Nullable_Object_Returning_Null.yaml
@@ -90,7 +90,7 @@ sourceSchemas:
         productById(id: ID!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         fieldWithNullableRequirement(
           nullableArgument: String @require(field: "nullableObject.field")
         ): String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup.yaml
index ffc2081c276..0ecf8b6886c 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup.yaml
@@ -42,7 +42,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -120,7 +120,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml
index 68d8f107746..2aff0a2416a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml
@@ -46,7 +46,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -126,7 +126,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Levels.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Levels.yaml
index c7d4f546037..6d7fa4c0329 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Levels.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Parent_Fields_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Levels.yaml
@@ -50,7 +50,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -132,7 +132,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields.yaml
index 3ee1415fe10..477030314f3 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields.yaml
@@ -38,7 +38,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -110,7 +110,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields_With_Extra_Fields_On_Shared_Level.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields_With_Extra_Fields_On_Shared_Level.yaml
index 6f5bd450964..728dedbc797 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields_With_Extra_Fields_On_Shared_Level.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Hierarchy_Of_Shared_Root_Fields_With_Extra_Fields_On_Shared_Level.yaml
@@ -44,7 +44,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -118,7 +118,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup.yaml
index 1dbb1793ed4..5eabbc1b26e 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup.yaml
@@ -38,7 +38,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -112,7 +112,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml
index 2b5802a9f76..bc6e9307749 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Extra_Fields_On_Shared_Level.yaml
@@ -42,7 +42,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -118,7 +118,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Type_Refinement.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Type_Refinement.yaml
index 7c02b74274c..4bb24666686 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Type_Refinement.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Shared_Parent_Field_Below_Type_With_Lookup_With_Type_Refinement.yaml
@@ -40,7 +40,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -118,7 +118,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Interface_Root_Field_With_Type_Refinement.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Interface_Root_Field_With_Type_Refinement.yaml
index 825838c147b..f641250f64b 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Interface_Root_Field_With_Type_Refinement.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Interface_Root_Field_With_Type_Refinement.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -108,7 +108,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field.yaml
index 254f993bb95..0c56a032152 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field.yaml
@@ -34,7 +34,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -102,7 +102,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Extra_Fields_On_Root.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Extra_Fields_On_Root.yaml
index 949e03304b3..ce262459089 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Extra_Fields_On_Root.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Extra_Fields_On_Root.yaml
@@ -38,7 +38,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -108,7 +108,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Inline_Fragment_Without_TypeCondition.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Inline_Fragment_Without_TypeCondition.yaml
index d2f19443149..76739f0d8fb 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Inline_Fragment_Without_TypeCondition.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Root_Field_With_Inline_Fragment_Without_TypeCondition.yaml
@@ -40,7 +40,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -114,7 +114,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Union_Root_Field_With_Type_Refinement.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Union_Root_Field_With_Type_Refinement.yaml
index 89ece964fda..f3573cb4486 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Union_Root_Field_With_Type_Refinement.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SharedPathTests.Single_Shared_Union_Root_Field_With_Type_Refinement.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema1: String!
         shared: SharedProduct @shareable
@@ -108,7 +108,7 @@ sourceSchemas:
         topReview: Review! @shareable
       }
 
-      type Product implements IInterface {
+      type Product implements IInterface @key(fields: "id") {
         id: Int!
         schema2: String!
         shared: SharedProduct @shareable
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_CustomAcceptHeader.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_CustomAcceptHeader.yaml
index 04128c845ee..40f4221b9de 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_CustomAcceptHeader.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_CustomAcceptHeader.yaml
@@ -33,11 +33,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -77,12 +77,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching.yaml
index 567ecdcc1ac..c17cb9787fe 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching.yaml
@@ -33,11 +33,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -77,12 +77,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml
index 2fab8c6aed1..27f84396335 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml
@@ -33,11 +33,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -77,12 +77,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml
index 1f127b96edb..108055efff3 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml
@@ -33,11 +33,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -77,12 +77,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyVariableBatching.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyVariableBatching.yaml
index 3ecc9afe4ea..ab0b4ef3992 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyVariableBatching.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.BatchRequest_OnlyVariableBatching.yaml
@@ -33,11 +33,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -77,12 +77,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_CustomAcceptHeader.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_CustomAcceptHeader.yaml
index 582e66cfd98..3777c8118df 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_CustomAcceptHeader.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_CustomAcceptHeader.yaml
@@ -48,11 +48,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -107,12 +107,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching.yaml
index 9479858f6f8..f8c244a04d9 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching.yaml
@@ -48,11 +48,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -107,12 +107,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml
index 8618d9b357c..5f2d07fbe7f 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsJsonArray.yaml
@@ -78,11 +78,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -137,12 +137,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml
index a1d84904ac2..09ca221cb88 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyRequestBatching_ServerReturnsNoRequestIndices.yaml
@@ -78,11 +78,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -137,12 +137,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyVariableBatching.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyVariableBatching.yaml
index 5235697e53c..59bc0b35922 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyVariableBatching.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.OperationBatch_BatchRequest_OnlyVariableBatching.yaml
@@ -48,11 +48,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
@@ -107,12 +107,12 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         name(postFix: String): String!
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         rating: String!
         id: ID!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.SingularRequest_CustomAcceptHeader.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.SingularRequest_CustomAcceptHeader.yaml
index 83dd7738883..397bdd23f4c 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.SingularRequest_CustomAcceptHeader.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaClientCapabilitiesTests.SingularRequest_CustomAcceptHeader.yaml
@@ -33,11 +33,11 @@ sourceSchemas:
         authorById(id: ID!): Author @lookup @internal
       }
 
-      type Author {
+      type Author @key(fields: "id") {
         id: ID!
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         author: Author
         id: ID!
         title: String!
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Null.yaml
index 83cf6bdb0a4..3af98f79194 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Null.yaml
@@ -68,7 +68,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -113,7 +113,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Propagate.yaml
index e58b5e5d6c0..8ac7653c6db 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_In_List_OnError_Propagate.yaml
@@ -67,7 +67,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -112,7 +112,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Null.yaml
index 1c73e04e4ca..ac3853868be 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Null.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -76,7 +76,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Propagate.yaml
index 7ab17114708..42ea2b5f475 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Field_OnError_Propagate.yaml
@@ -40,7 +40,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -75,7 +75,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Null.yaml
index 52dfed2e497..e6720d3b280 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Null.yaml
@@ -68,7 +68,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -113,7 +113,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Propagate.yaml
index 6121dd54f1c..58ce1c5e1a2 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_NonNull_OnError_Propagate.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -80,7 +80,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Null.yaml
index 8b4d28463b3..59c4dab3c82 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Null.yaml
@@ -68,7 +68,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -113,7 +113,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Propagate.yaml
index aee474a6fad..117546d64d6 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_In_List_OnError_Propagate.yaml
@@ -67,7 +67,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -112,7 +112,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Null.yaml
index 53a4ab9dd94..2384a2ff084 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Null.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -76,7 +76,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Propagate.yaml
index dcf1c8c2670..112d23624cb 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_NonNull_OnError_Propagate.yaml
@@ -34,7 +34,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -69,7 +69,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Null.yaml
index 61508a9239b..8f9fae06925 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Null.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -76,7 +76,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Propagate.yaml
index 7f452e8700d..859b79a26c5 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Lookup_Leaf_OnError_Propagate.yaml
@@ -40,7 +40,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -75,7 +75,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Null.yaml
index f81de6ecdd1..f99f9a5b572 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Null.yaml
@@ -33,7 +33,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Propagate.yaml
index 110c5102582..9b45a6d8ef8 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Field_OnError_Propagate.yaml
@@ -32,7 +32,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Null.yaml
index a69d23ec1a6..c5ffc9df08e 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Null.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Propagate.yaml
index ccf98fb9692..05a7ee61d0a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.Error_On_Root_Leaf_OnError_Propagate.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Null.yaml
index 1b4f43623ee..c32e478ff3a 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Null.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -76,7 +76,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Propagate.yaml
index 98bc37edf5f..5fd290c2940 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Lookup_Leaf_NonNull_OnError_Propagate.yaml
@@ -34,7 +34,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -69,7 +69,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Null.yaml
index a7e46b8036a..d948fc59410 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Null.yaml
@@ -33,7 +33,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Propagate.yaml
index 58cc0980fc3..3b83866e6d8 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_With_Path_For_Root_Field_NonNull_OnError_Propagate.yaml
@@ -32,7 +32,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Null.yaml
index 7f2c36da889..5daa1b69e58 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Null.yaml
@@ -44,7 +44,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -79,7 +79,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Propagate.yaml
index 09fa8db54cb..27f43a44a37 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Lookup_Field_NonNull_OnError_Propagate.yaml
@@ -37,7 +37,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -72,7 +72,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Null.yaml
index 4374045bb31..def21f67762 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Null.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Propagate.yaml
index 3b14899dc6c..08971581389 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_NonNull_OnError_Propagate.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Null.yaml
index 13d4622926f..3113425066b 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Null.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Propagate.yaml
index a2be0622d07..7109deb9298 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.No_Data_And_Error_Without_Path_For_Root_Field_OnError_Propagate.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_Null_OnSourceSchema_Forwards_To_Subgraph_Request.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_Null_OnSourceSchema_Forwards_To_Subgraph_Request.yaml
index 63bb50e881c..e8180cf3f1c 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_Null_OnSourceSchema_Forwards_To_Subgraph_Request.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_Null_OnSourceSchema_Forwards_To_Subgraph_Request.yaml
@@ -32,7 +32,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_PerRequestOverride_IsIgnored_When_AllowErrorHandlingModeOverride_IsDisabled.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_PerRequestOverride_IsIgnored_When_AllowErrorHandlingModeOverride_IsDisabled.yaml
index 22721af12fb..19a7af3ecfd 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_PerRequestOverride_IsIgnored_When_AllowErrorHandlingModeOverride_IsDisabled.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_PerRequestOverride_IsIgnored_When_AllowErrorHandlingModeOverride_IsDisabled.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -70,7 +70,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_SchemaDefault_Null_AppliesWithoutPerRequestOverride.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_SchemaDefault_Null_AppliesWithoutPerRequestOverride.yaml
index eb875e7f98e..02e02296148 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_SchemaDefault_Null_AppliesWithoutPerRequestOverride.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.OnError_SchemaDefault_Null_AppliesWithoutPerRequestOverride.yaml
@@ -32,7 +32,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Null.yaml
index ac167bd2725..4681b11b32e 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Null.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -76,7 +76,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Propagate.yaml
index 79319bb245e..97280badffd 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_NonNull_OnError_Propagate.yaml
@@ -34,7 +34,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -69,7 +69,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Null.yaml
index 11eedabdf51..c599ed5f4b8 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Null.yaml
@@ -41,7 +41,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -76,7 +76,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Propagate.yaml
index a2cbd4606c6..691244b5b1f 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_OnError_Propagate.yaml
@@ -40,7 +40,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -75,7 +75,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Null.yaml
index d7249f6950d..ca636bc79b9 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Null.yaml
@@ -68,7 +68,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -113,7 +113,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Propagate.yaml
index 39764677afa..a84eda69af5 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_NonNull_OnError_Propagate.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -80,7 +80,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String!
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Null.yaml
index 879a3bdf913..4b2cf47bab1 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Null.yaml
@@ -68,7 +68,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -113,7 +113,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Propagate.yaml
index 77d09f0e86a..d48ff03ead4 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Lookup_On_List_OnError_Propagate.yaml
@@ -67,7 +67,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
@@ -112,7 +112,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         name: String
         id: Int!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Null.yaml
index 6c1dc59d92b..7fc5314acf5 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Null.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Propagate.yaml
index 3d0326d80c8..2e3e1c5a2fc 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_NonNull_OnError_Propagate.yaml
@@ -32,7 +32,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Null.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Null.yaml
index dfb1839e510..963a56410d7 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Null.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Null.yaml
@@ -36,7 +36,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Propagate.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Propagate.yaml
index e637395f185..5be5096f363 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Propagate.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SourceSchemaErrorTests.SourceSchema_Request_Fails_For_Root_Field_OnError_Propagate.yaml
@@ -35,7 +35,7 @@ sourceSchemas:
         productById(id: Int!): Product @lookup @internal
       }
 
-      type Product {
+      type Product @key(fields: "id") {
         id: Int!
         price: Float!
       }
diff --git a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SubscriptionsOverHttpStoreTests.Subscribe_Simple.yaml b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SubscriptionsOverHttpStoreTests.Subscribe_Simple.yaml
index 7659f80ef13..a37760afe4e 100644
--- a/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SubscriptionsOverHttpStoreTests.Subscribe_Simple.yaml
+++ b/src/HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/__snapshots__/SubscriptionsOverHttpStoreTests.Subscribe_Simple.yaml
@@ -100,7 +100,7 @@ sourceSchemas:
         bookById(id: Int!): Book @internal @lookup
       }
 
-      type Book {
+      type Book @key(fields: "id") {
         id: Int!
         title: String!
       }