microsoft · JoshLove-msft · Jan 17, 2026 · Jan 17, 2026 · Jan 17, 2026 · Jan 17, 2026
@@ -51,8 +51,6 @@ export function createModel(sdkContext: CSharpEmitterContext): CodeModel {
   fixNamingConflicts(models, constants);
 
   const clientModel: CodeModel = {
-    // To ensure deterministic library name, customers would need to set the package-name property as the ordering of the namespaces could change
-    // if the typespec is changed.
     name: getClientNamespaceString(sdkContext)!,
     apiVersions: rootApiVersions,
     enums: enums,

@@ -144,22 +144,31 @@ export function getClientNamespaceString(context: CSharpEmitterContext): string
   const packageName = context.emitContext.options["package-name"];
   const serviceNamespaces = listAllServiceNamespaces(context);
   const firstNamespace = serviceNamespaces.length > 0 ? serviceNamespaces[0] : undefined;
+  // namespace is not a public emitter option, but it is supported by TCGC
+  const namespaceOverride = (context.emitContext.options as any).namespace;
 
   if (packageName) {
-    return getClientNamespaceStringHelper(packageName, firstNamespace);
+    return getClientNamespaceStringHelper(namespaceOverride, packageName, firstNamespace);
   }
 
   if (containsMultiServiceClient(context.sdkPackage.clients)) {
-    return getClientNamespaceStringHelper(context.sdkPackage.clients[0].namespace);
+    return getClientNamespaceStringHelper(
+      namespaceOverride,
+      context.sdkPackage.clients[0].namespace,
+    );
   }
 
-  return getClientNamespaceStringHelper(undefined, firstNamespace);
+  return getClientNamespaceStringHelper(namespaceOverride, undefined, firstNamespace);
 }
 
 export function getClientNamespaceStringHelper(
+  namespaceOverride?: string,
   packageName?: string,
   namespace?: Namespace,
 ): string | undefined {
+  if (namespaceOverride) {
+    return namespaceOverride;
+  }
   if (packageName) {
     packageName = packageName
       .replace(/-/g, ".")

@@ -1,7 +1,8 @@
+import { listAllServiceNamespaces } from "@azure-tools/typespec-client-generator-core";
 import * as childProcess from "child_process";
 import { EventEmitter } from "events";
 import { beforeEach, describe, expect, it, vi } from "vitest";
-import { execCSharpGenerator } from "../../src/lib/utils.js";
+import { execCSharpGenerator, getClientNamespaceStringHelper } from "../../src/lib/utils.js";
 import { CSharpEmitterContext } from "../../src/sdk-context.js";
 import {
   createCSharpSdkContext,
@@ -84,3 +85,42 @@ describe("execCSharpGenerator tests", () => {
     expect(result.exitCode).toBe(0);
   });
 });
+
+describe("getClientNamespaceStringHelper", () => {
+  it("should return the formatted package name when namespace is undefined", () => {
+    expect(getClientNamespaceStringHelper(undefined, "client-plane-generated")).toBe(
+      "Client.Plane.Generated",
+    );
+    expect(getClientNamespaceStringHelper(undefined, "client-plane-Generated")).toBe(
+      "Client.Plane.Generated",
+    );
+    expect(getClientNamespaceStringHelper(undefined, "client-Plane-generated")).toBe(
+      "Client.Plane.Generated",
+    );
+  });
+
+  it("should handle dots in package name", () => {
+    expect(getClientNamespaceStringHelper(undefined, "client.plane.generated")).toBe(
+      "Client.Plane.Generated",
+    );
+  });
+
+  it("should return namespace override when provided", async () => {
+    expect(getClientNamespaceStringHelper("Namespace.Override", "Package.Name")).toBe(
+      "Namespace.Override",
+    );
+  });
+
+  it("should fallback to Namespace from spec when namespace and package are not provided", async () => {
+    const runner = await createEmitterTestHost();
+    const program = await typeSpecCompile(``, runner, { IsVersionNeeded: false });
+
+    const context = createEmitterContext(program);
+    const sdkContext = await createCSharpSdkContext(context);
+    const primaryNamespace = listAllServiceNamespaces(sdkContext)[0];
+
+    expect(getClientNamespaceStringHelper(undefined, undefined, primaryNamespace)).toBe(
+      "Azure.Csharp.Testing",
+    );
+  });
+});
@@ -21,7 +21,7 @@ public class ModelReaderWriterContextDefinition : TypeProvider
         private static readonly CSharpTypeNameComparer s_cSharpTypeNameComparer = new CSharpTypeNameComparer();
         private static readonly TypeProviderTypeNameComparer s_typeProviderNameComparer = new TypeProviderTypeNameComparer();
 
-        internal static readonly string s_name = $"{ScmCodeModelGenerator.Instance.TypeFactory.ServiceName}Context";
+        internal static readonly string s_name = $"{RemovePeriods(ScmCodeModelGenerator.Instance.TypeFactory.PrimaryNamespace)}Context";
 
         protected override string BuildName() => s_name;
 

@@ -435,7 +435,7 @@ public EnumCacheKey(InputEnumType enumType, TypeProvider? declaringType)
         }
 
         private string? _primaryNamespace;
-        internal string PrimaryNamespace => _primaryNamespace ??= GetCleanNameSpace(CodeModelGenerator.Instance.InputLibrary.InputNamespace.Name);
+        public string PrimaryNamespace => _primaryNamespace ??= GetCleanNameSpace(CodeModelGenerator.Instance.InputLibrary.InputNamespace.Name);
 
         public string ServiceName => _serviceName ??= BuildServiceName();
         private string? _serviceName;

@@ -10,7 +10,7 @@ namespace Encode._Array
     [ModelReaderWriterBuildable(typeof(NewlineDelimitedArrayProperty))]
     [ModelReaderWriterBuildable(typeof(PipeDelimitedArrayProperty))]
     [ModelReaderWriterBuildable(typeof(SpaceDelimitedArrayProperty))]
-    public partial class EncodeArrayContext : ModelReaderWriterContext
+    public partial class Encode_ArrayContext : ModelReaderWriterContext
     {
     }
 }
@@ -7,7 +7,7 @@
 namespace _Type._Array
 {
     [ModelReaderWriterBuildable(typeof(InnerModel))]
-    public partial class TypeArrayContext : ModelReaderWriterContext
+    public partial class _Type_ArrayContext : ModelReaderWriterContext
     {
     }
 }
@@ -7,7 +7,7 @@
 namespace _Type.Dictionary
 {
     [ModelReaderWriterBuildable(typeof(InnerModel))]
-    public partial class TypeDictionaryContext : ModelReaderWriterContext
+    public partial class _TypeDictionaryContext : ModelReaderWriterContext
     {
     }
 }
@@ -6,7 +6,7 @@
 
 namespace _Type._Enum.Extensible
 {
-    public partial class TypeEnumExtensibleContext : ModelReaderWriterContext
+    public partial class _Type_EnumExtensibleContext : ModelReaderWriterContext
     {
     }
 }
@@ -6,7 +6,7 @@
 
 namespace _Type._Enum.Fixed
 {
-    public partial class TypeEnumFixedContext : ModelReaderWriterContext
+    public partial class _Type_EnumFixedContext : ModelReaderWriterContext
     {
     }
 }
@@ -9,7 +9,7 @@ namespace _Type.Model.Empty
     [ModelReaderWriterBuildable(typeof(EmptyInput))]
     [ModelReaderWriterBuildable(typeof(EmptyInputOutput))]
     [ModelReaderWriterBuildable(typeof(EmptyOutput))]
-    public partial class TypeModelEmptyContext : ModelReaderWriterContext
+    public partial class _TypeModelEmptyContext : ModelReaderWriterContext
     {
     }
 }
@@ -12,7 +12,7 @@ namespace _Type.Model.Inheritance.EnumDiscriminator
     [ModelReaderWriterBuildable(typeof(Snake))]
     [ModelReaderWriterBuildable(typeof(UnknownDog))]
     [ModelReaderWriterBuildable(typeof(UnknownSnake))]
-    public partial class TypeModelInheritanceEnumDiscriminatorContext : ModelReaderWriterContext
+    public partial class _TypeModelInheritanceEnumDiscriminatorContext : ModelReaderWriterContext
     {
     }
 }
@@ -13,7 +13,7 @@ namespace _Type.Model.Inheritance.NestedDiscriminator
     [ModelReaderWriterBuildable(typeof(Shark))]
     [ModelReaderWriterBuildable(typeof(UnknownFish))]
     [ModelReaderWriterBuildable(typeof(UnknownShark))]
-    public partial class TypeModelInheritanceNestedDiscriminatorContext : ModelReaderWriterContext
+    public partial class _TypeModelInheritanceNestedDiscriminatorContext : ModelReaderWriterContext
     {
     }
 }
@@ -9,7 +9,7 @@ namespace _Type.Model.Inheritance.NotDiscriminated
     [ModelReaderWriterBuildable(typeof(Cat))]
     [ModelReaderWriterBuildable(typeof(Pet))]
     [ModelReaderWriterBuildable(typeof(Siamese))]
-    public partial class TypeModelInheritanceNotDiscriminatedContext : ModelReaderWriterContext
+    public partial class _TypeModelInheritanceNotDiscriminatedContext : ModelReaderWriterContext
     {
     }
 }
@@ -8,7 +8,7 @@ namespace _Type.Model.Inheritance.Recursive
 {
     [ModelReaderWriterBuildable(typeof(Element))]
     [ModelReaderWriterBuildable(typeof(Extension))]
-    public partial class TypeModelInheritanceRecursiveContext : ModelReaderWriterContext
+    public partial class _TypeModelInheritanceRecursiveContext : ModelReaderWriterContext
     {
     }
 }
@@ -15,7 +15,7 @@ namespace _Type.Model.Inheritance.SingleDiscriminator
     [ModelReaderWriterBuildable(typeof(TRex))]
     [ModelReaderWriterBuildable(typeof(UnknownBird))]
     [ModelReaderWriterBuildable(typeof(UnknownDinosaur))]
-    public partial class TypeModelInheritanceSingleDiscriminatorContext : ModelReaderWriterContext
+    public partial class _TypeModelInheritanceSingleDiscriminatorContext : ModelReaderWriterContext
     {
     }
 }
@@ -9,7 +9,7 @@ namespace _Type.Model.Usage
     [ModelReaderWriterBuildable(typeof(InputOutputRecord))]
     [ModelReaderWriterBuildable(typeof(InputRecord))]
     [ModelReaderWriterBuildable(typeof(OutputRecord))]
-    public partial class TypeModelUsageContext : ModelReaderWriterContext
+    public partial class _TypeModelUsageContext : ModelReaderWriterContext
     {
     }
 }
@@ -8,7 +8,7 @@ namespace _Type.Model.Visibility
 {
     [ModelReaderWriterBuildable(typeof(ReadOnlyModel))]
     [ModelReaderWriterBuildable(typeof(VisibilityModel))]
-    public partial class TypeModelVisibilityContext : ModelReaderWriterContext
+    public partial class _TypeModelVisibilityContext : ModelReaderWriterContext
     {
     }
 }
@@ -45,7 +45,7 @@ namespace _Type.Property.AdditionalProperties
     [ModelReaderWriterBuildable(typeof(WidgetData0))]
     [ModelReaderWriterBuildable(typeof(WidgetData1))]
     [ModelReaderWriterBuildable(typeof(WidgetData2))]
-    public partial class TypePropertyAdditionalPropertiesContext : ModelReaderWriterContext
+    public partial class _TypePropertyAdditionalPropertiesContext : ModelReaderWriterContext
     {
     }
 }
@@ -14,7 +14,7 @@ namespace _Type.Property.Nullable
     [ModelReaderWriterBuildable(typeof(DurationProperty))]
     [ModelReaderWriterBuildable(typeof(InnerModel))]
     [ModelReaderWriterBuildable(typeof(StringProperty))]
-    public partial class TypePropertyNullableContext : ModelReaderWriterContext
+    public partial class _TypePropertyNullableContext : ModelReaderWriterContext
     {
     }
 }
@@ -22,7 +22,7 @@ namespace _Type.Property.Optional
     [ModelReaderWriterBuildable(typeof(UnionFloatLiteralProperty))]
     [ModelReaderWriterBuildable(typeof(UnionIntLiteralProperty))]
     [ModelReaderWriterBuildable(typeof(UnionStringLiteralProperty))]
-    public partial class TypePropertyOptionalContext : ModelReaderWriterContext
+    public partial class _TypePropertyOptionalContext : ModelReaderWriterContext
     {
     }
 }
@@ -36,7 +36,7 @@ namespace _Type.Property.ValueTypes
     [ModelReaderWriterBuildable(typeof(UnknownDictProperty))]
     [ModelReaderWriterBuildable(typeof(UnknownIntProperty))]
     [ModelReaderWriterBuildable(typeof(UnknownStringProperty))]
-    public partial class TypePropertyValueTypesContext : ModelReaderWriterContext
+    public partial class _TypePropertyValueTypesContext : ModelReaderWriterContext
     {
     }
 }
@@ -6,7 +6,7 @@
 
 namespace _Type.Scalar
 {
-    public partial class TypeScalarContext : ModelReaderWriterContext
+    public partial class _TypeScalarContext : ModelReaderWriterContext
     {
     }
 }
@@ -8,7 +8,7 @@ namespace _Type.Union.Discriminated
 {
     [ModelReaderWriterBuildable(typeof(Cat))]
     [ModelReaderWriterBuildable(typeof(Dog))]
-    public partial class TypeUnionDiscriminatedContext : ModelReaderWriterContext
+    public partial class _TypeUnionDiscriminatedContext : ModelReaderWriterContext
     {
     }
 }
@@ -22,7 +22,7 @@ namespace _Type.Union
     [ModelReaderWriterBuildable(typeof(MixedLiteralsCases))]
     [ModelReaderWriterBuildable(typeof(MixedTypesCases))]
     [ModelReaderWriterBuildable(typeof(StringAndArrayCases))]
-    public partial class TypeUnionContext : ModelReaderWriterContext
+    public partial class _TypeUnionContext : ModelReaderWriterContext
     {
     }
 }