[Draft] Add generated C# full-generation benchmarks

.chronus/changes/mtg-hybrid-reference-map-2026-06-19-08-41-23.md

@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-client-csharp"
+---
+
+Improve C# generator post-processing reference-map parity and performance.

.chronus/changes/mtg-hybrid-reference-map-2026-07-01-02-43-39.md

@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-client-csharp"
+---
+
+Improve generated C# reference-map analysis by deriving generated body references from provider expression trees.

.chronus/changes/mtg-hybrid-reference-map-2026-07-06-02-27-00.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-csharp"
+---
+
+Preserve generated SDK compatibility when using the optimized C# reference map.

.chronus/changes/mtg-manual-name-reduction-experiment-2026-06-23-07-14-07.md

@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-client-csharp"
+---
+
+Tune hybrid provider reference-map benchmark parity and performance.

.chronus/config.yaml

@@ -71,6 +71,7 @@ versionPolicies:
 changelog: ["@chronus/github/changelog", { repo: "microsoft/typespec" }]
 
 additionalPackages:
+  - packages/http-client-csharp
   - packages/http-client-python
   - packages/http-client-java
 

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientOptionsProvider.cs

@@ -248,6 +248,11 @@ private static bool UseSingletonInstance(InputClient inputClient)
 
         protected override string BuildRelativeFilePath() => Path.Combine("src", "Generated", $"{Name}.cs");
 
+        protected override bool ShouldWriteTypeXmlDocs => CustomCodeView is null;
+
+        protected override TypeSignatureModifiers BuildDeclarationModifiers()
+            => _clientProvider.DeclarationModifiers & (TypeSignatureModifiers.Public | TypeSignatureModifiers.Internal | TypeSignatureModifiers.Protected | TypeSignatureModifiers.Private);
+
         protected override string BuildName()
         {
             if (UseSingletonInstance(_inputClient))

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientPipelineExtensionsDefinition.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Threading.Tasks;
 using Microsoft.TypeSpec.Generator.ClientModel.Snippets;
@@ -52,6 +53,9 @@ protected override MethodProvider[] BuildMethods()
             ];
         }
 
+        protected override IReadOnlyList<CSharpType> BuildBodyDependencyTypes()
+            => [ErrorResultSnippets.ErrorResultType];
+
         private MethodProvider ProcessHeadAsBoolMessage()
         {
             MethodSignature signature = GetProcessHeadAsBoolMessageSignature(false);

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientProvider.cs

@@ -43,6 +43,7 @@ private record ApiVersionFields(FieldProvider Field, PropertyProvider? Correspon
         private const string ClientSuffix = "Client";
         private readonly FormattableString _publicCtorDescription;
         private readonly InputClient _inputClient;
+        protected override bool IsClientProvider => true;
         internal InputClient InputClient => _inputClient;
         private readonly InputAuth? _inputAuth;
         private readonly ParameterProvider _endpointParameter;
@@ -426,6 +427,42 @@ private IReadOnlyList<ParameterProvider> GetClientParameters()
 
         protected override string BuildName() => _inputClient.IsExactName ? _inputClient.Name : _inputClient.Name.ToIdentifierName();
 
+        protected override IReadOnlyList<CSharpType> BuildHelperDependencyTypes()
+        {
+            foreach (var method in Methods.OfType<ScmMethodProvider>())
+            {
+                if (method.BodyStatements != null)
+                {
+                    return [new CancellationTokenExtensionsDefinition().Type, new ClientPipelineExtensionsDefinition().Type];
+                }
+            }
+
+            return [];
+        }
+
+        protected override IReadOnlyList<CSharpType> BuildBodyDependencyTypes()
+        {
+            var dependencies = new List<CSharpType>();
+            foreach (var method in Methods.OfType<ScmMethodProvider>())
+            {
+                if (method.BodyStatements == null)
+                {
+                    continue;
+                }
+
+                if (method.CollectionDefinition != null)
+                {
+                    dependencies.Add(method.CollectionDefinition.Type);
+                }
+
+                // Service method metadata can mention wire-only request/response models that are not
+                // emitted in the generated method signature or body. The graph builder and structured
+                // body scanner capture the generated types that are actually referenced.
+            }
+
+            return dependencies;
+        }
+
         protected override FieldProvider[] BuildFields()
         {
             List<FieldProvider> fields = [EndpointField];

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientUriBuilderDefinition.cs

@@ -28,6 +28,7 @@ internal sealed class ClientUriBuilderDefinition : TypeProvider
         private readonly FieldProvider _uriBuilderField;
         private readonly FieldProvider _pathAndQueryField;
         private readonly FieldProvider _pathLengthField;
+        protected override bool IncludeGeneratedBodyReferences => true;
 
         private PropertyProvider? _uriBuilderProperty;
         private PropertyProvider UriBuilderProperty => _uriBuilderProperty ??= new(

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/CollectionResultDefinition.cs

@@ -217,6 +217,22 @@ private bool HasPagingOperationNameCollision(string operationName)
         protected override TypeSignatureModifiers BuildDeclarationModifiers()
             => TypeSignatureModifiers.Internal | TypeSignatureModifiers.Partial | TypeSignatureModifiers.Class;
 
+        protected override IReadOnlyList<CSharpType> BuildBodyDependencyTypes()
+        {
+            var dependencies = new List<CSharpType> { Client.Type, ResponseModelType, NextPagePropertyType };
+            if (ItemModelType != null)
+            {
+                dependencies.Add(ItemModelType);
+            }
+
+            foreach (var field in RequestFields)
+            {
+                dependencies.Add(field.Type);
+            }
+
+            return dependencies;
+        }
+
         protected override FieldProvider[] BuildFields() => [ClientField, .. RequestFields];
 
         protected override CSharpType[] BuildImplements() =>

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.cs

@@ -117,6 +117,10 @@ public MrwSerializationTypeDefinition(InputModelType inputModel, ModelProvider m
 
         protected override CSharpType? BuildBaseType() => _model.BaseType;
 
+        protected override IReadOnlyList<CSharpType> BuildHelperDependencyTypes() => _rawDataField != null || _additionalProperties.Value.Length > 0
+            ? [ChangeTrackingDictionaryType]
+            : [];
+
         protected override SuppressionStatement[] BuildDisabledFileWarnings()
         {
             if (_model.CanonicalView.Properties.Any(p => ScmModelProvider.IsFileBinaryContentType(p.Type)))

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MultipartFormDataSerializationDefinition.cs

@@ -51,6 +51,12 @@ protected override string BuildRelativeFilePath()
             return Path.Combine("src", "Generated", "Models", $"{Name}.Serialization.Multipart.cs");
         }
 
+        protected override IReadOnlyList<CSharpType> BuildHelperDependencyTypes() => _model.Properties.Any(
+            prop => prop.WireInfo != null && !prop.WireInfo.IsRequired &&
+                (prop.Type is { IsCollection: true, IsReadOnlyMemory: false } || prop.Type.IsDictionary))
+            ? [OptionalType]
+            : [];
+
         protected override SuppressionStatement[] BuildDisabledFileWarnings()
             => [new SuppressionStatement(null, Literal(ScmModelProvider.FileBinaryContentDiagnosticId), ScmModelProvider.ScmEvaluationTypeSuppressionJustification)];
 

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/RestClientProvider.cs

@@ -78,6 +78,43 @@ protected override FieldProvider[] BuildFields()
             return [.. pipelineMessage20xClassifiersFields];
         }
 
+        protected override IReadOnlyList<CSharpType> BuildHelperDependencyTypes()
+        {
+            var dependencies = new List<CSharpType> { new ClientUriBuilderDefinition().Type };
+            foreach (var serviceMethod in _inputClient.Methods)
+            {
+                foreach (var parameter in serviceMethod.Operation.Parameters)
+                {
+                    if (parameter is not InputHeaderParameter and not InputQueryParameter)
+                    {
+                        continue;
+                    }
+
+                    var type = ScmCodeModelGenerator.Instance.TypeFactory.CreateCSharpType(parameter.Type);
+                    if (type?.IsDictionary == true)
+                    {
+                        AddDependency(dependencies, ChangeTrackingDictionaryType);
+                    }
+                    else if (type?.IsCollection == true)
+                    {
+                        AddDependency(dependencies, ChangeTrackingListType);
+                    }
+                }
+            }
+
+            return dependencies;
+        }
+
+        private static void AddDependency(List<CSharpType> dependencies, CSharpType dependency)
+        {
+            if (!dependencies.Any(existing =>
+                existing.Name == dependency.Name &&
+                existing.Namespace == dependency.Namespace))
+            {
+                dependencies.Add(dependency);
+            }
+        }
+
         protected override ScmMethodProvider[] BuildMethods()
         {
             List<ScmMethodProvider> methods = new List<ScmMethodProvider>();

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/SerializationFormatDefinition.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -45,6 +46,7 @@ protected override TypeSignatureModifiers BuildDeclarationModifiers()
         protected override string BuildRelativeFilePath() => Path.Combine("src", "Generated", "Internal", $"{Name}.cs");
 
         protected override string BuildName() => "SerializationFormat";
+        protected override FormattableString BuildDescription() => $"The serialization format.";
 
         protected override TypeProvider[] BuildSerializationProviders() => [];
 

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Snippets/HttpRequestApiSnippets.cs

@@ -26,7 +26,9 @@ public static MethodBodyStatement SetContent(this ScopedApi<PipelineRequest> pip
         public static MethodBodyStatement SetHeaderDelimited(this HttpRequestApi pipelineRequest, string name, ValueExpression value, ValueExpression delimiter, ValueExpression? format = null)
         {
             ValueExpression[] parameters = format != null ? [Literal(name), value, delimiter, format] : [Literal(name), value, delimiter];
-            return pipelineRequest.Property(nameof(PipelineRequest.Headers)).Invoke("SetDelimited", parameters).Terminate();
+            return pipelineRequest.Property(nameof(PipelineRequest.Headers))
+                .Invoke("SetDelimited", parameters, typeArguments: null, callAsAsync: false, extensionType: new PipelineRequestHeadersExtensionsDefinition().Type)
+                .Terminate();
         }
     }
 }