Azure · Copilot · Feb 11, 2026 · Feb 11, 2026 · Feb 11, 2026 · Feb 11, 2026
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/azure-http-specs"
+---
+
+Update `azure-http-specs` samples to replace deprecated `@operationGroup` usage with `@client`, including structure and naming scenarios, so samples align with the consolidated client hierarchy design.
@@ -0,0 +1,12 @@
+changeKind: breaking
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+This change adds multiple-services client support and consolidates client hierarchy customization around `@client`. Cross-service clients now expose `apiVersionsMap` on `SdkClientType`, and multi-service hierarchy scenarios are supported, including mixed multi-service and single-service clients and nested `@client` definitions.
+
+This change is breaking because when multiple `@service` namespaces exist without explicit `@client`, TCGC now creates a separate root client for each service instead of only using the first service and emitting the `multiple-services` warning.
+
+`@operationGroup` is now deprecated in favor of nested `@client`, and `SdkOperationGroup` is deprecated in favor of `SdkClient`-based hierarchy customization while retaining backward compatibility for existing usage.
+
+Migration guide: if you relied on implicit first-service-only behavior, either remove extra `@service` declarations or add explicit `@client` decorators to control which services are included and how hierarchy is shaped.
@@ -27,7 +27,7 @@ model AzureEmbeddingModel {
   embedding: EmbeddingVector<int32>;
 }
 
-@operationGroup
+@client
 @route("/embeddingVector")
 interface AzureCoreEmbeddingVector {
   #suppress "@azure-tools/typespec-azure-core/use-standard-operations" "For testing"

@@ -27,7 +27,7 @@ model AzureLocationModel {
   location: azureLocation;
 }
 
-@operationGroup
+@client
 @route("/azureLocation")
 interface AzureLocationScalar {
   #suppress "@azure-tools/typespec-azure-core/use-standard-operations" "For testing"

@@ -53,7 +53,7 @@ namespace SecondNamespace {
   }
 }
 
-@operationGroup
+@client
 @route("/first")
 interface FirstOperations {
   @scenario
@@ -69,7 +69,7 @@ interface FirstOperations {
   first(@body body: FirstNamespace.FirstModel): FirstNamespace.FirstModel;
 }
 
-@operationGroup
+@client
 @route("/second")
 interface SecondOperations {
   @scenario

@@ -143,7 +143,7 @@ namespace Header {
 }
 
 @route("/model")
-@operationGroup
+@client
 @clientName("ModelClient")
 namespace Model {
   @clientName("CSModel", "csharp")
@@ -192,7 +192,7 @@ namespace Model {
   op language(@bodyRoot body: ModelWithLanguageClientName): NoContentResponse;
 }
 
-@operationGroup
+@client
 @route("/union-enum")
 namespace UnionEnum {
   @clientName("ClientExtensibleEnum")

@@ -27,13 +27,13 @@ using Spector;
 namespace Client.Structure.ClientOperationGroup {
   op one is Client.Structure.Service.one;
 
-  @operationGroup
+  @client
   interface Group3 {
     two is Client.Structure.Service.two;
     three is Client.Structure.Service.Foo.three;
   }
 
-  @operationGroup
+  @client
   interface Group4 {
     four is Client.Structure.Service.Foo.four;
   }
@@ -69,7 +69,7 @@ namespace Client.Structure.AnotherClientOperationGroup {
   op five is Client.Structure.Service.Bar.five;
 
   #suppress "@azure-tools/typespec-client-generator-core/client-service" "issue https://github.com/Azure/typespec-azure/issues/1326"
-  @operationGroup
+  @client
   interface Group5 {
     six is Client.Structure.Service.Bar.six;
   }

@@ -8,7 +8,7 @@ using Azure.ClientGenerator;
 using Azure.ClientGenerator.Core;
 
 @doc("""
-  Test that we can use @client and @operationGroup decorators to customize client side code structure, such as:
+  Test that we can use @client decorators (including nested @client) to customize client side code structure, such as:
   1. have everything as default.
   2. to rename client or operation group
   3. one client can have more than one operations groups

@@ -32,7 +32,7 @@ op renamedThree is Client.Structure.Service.Foo.three;
 op renamedFive is Client.Structure.Service.Bar.five;
 
 // Those operations are renamed inside an operation group
-@operationGroup
+@client
 interface Group {
   renamedTwo is Client.Structure.Service.two;
   renamedFour is Client.Structure.Service.Foo.four;

@@ -27,14 +27,14 @@ using Spector;
 @scenario
 namespace Client.Structure.TwoOperationGroup;
 
-@operationGroup
+@client
 interface Group1 {
   one is Client.Structure.Service.one;
   three is Client.Structure.Service.Foo.three;
   four is Client.Structure.Service.Foo.four;
 }
 
-@operationGroup
+@client
 interface Group2 {
   two is Client.Structure.Service.two;
   five is Client.Structure.Service.Bar.five;

@@ -973,9 +973,7 @@ model MyModel {
 
 #### `@operationGroup`
 
-Define the sub client generated in the client SDK.
-If there is any `@client` definition or `@operationGroup` definition, then each `@client` is a root client and each `@operationGroup` is a sub client with hierarchy.
-This decorator cannot be used along with `@clientLocation`. This decorator cannot be used as augmentation.
+_Deprecated: Use @client instead. Nested @client decorators now serve the same purpose as @operationGroup._
 
 ```typespec
 @Azure.ClientGenerator.Core.operationGroup(scope?: valueof string)

@@ -196,10 +196,13 @@ export type ClientDecorator = (
 ) => DecoratorValidatorCallbacks | void;
 
 /**
+ *
+ *
+ *
+ * @deprecated Use `@client` instead. Nested `@client` decorators now serve the same purpose as `@operationGroup`.
  * Define the sub client generated in the client SDK.
  * If there is any `@client` definition or `@operationGroup` definition, then each `@client` is a root client and each `@operationGroup` is a sub client with hierarchy.
  * This decorator cannot be used along with `@clientLocation`. This decorator cannot be used as augmentation.
- *
  * @param target The target namespace or interface that you want to define as a sub client.
  * @param scope Specifies the target language emitters that the decorator should apply. If not set, the decorator will be applied to all language emitters by default.
  *

@@ -199,6 +199,7 @@ model ClientOptions {
 }
 
 /**
+ * @deprecated Use `@client` instead. Nested `@client` decorators now serve the same purpose as `@operationGroup`.
  * Define the sub client generated in the client SDK.
  * If there is any `@client` definition or `@operationGroup` definition, then each `@client` is a root client and each `@operationGroup` is a sub client with hierarchy.
  * This decorator cannot be used along with `@clientLocation`. This decorator cannot be used as augmentation.
@@ -218,6 +219,7 @@ model ClientOptions {
  * interface MyInterface{}
  * ```
  */
+#deprecated "Use @client instead. Nested @client decorators now serve the same purpose as @operationGroup."
 extern dec operationGroup(target: Namespace | Interface, scope?: valueof string);
 
 /**