Revert "[tcgc] one client multiple services (#3460)"

.chronus/changes/tcgc-revertMultiServiceCurrent-2025-11-9-13-38-59.md

@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+Roll back multi-service change

packages/typespec-client-generator-core/lib/decorators.tsp

@@ -172,11 +172,6 @@ model ClientOptions {
    * The name of the client. If not specified, the default name will be `<Name of the target>Client`.
    */
   name?: string;
-
-  /**
-   * The parent client of this client. If specified, this client will be generated as a sub client of the parent client.
-   */
-  parent?: Namespace | Interface;
 }
 
 /**

packages/typespec-client-generator-core/src/cache.ts

@@ -111,22 +111,6 @@ export function prepareClientAndOperationCache(context: TCGCContext): void {
       // operations directly under the group
       const operations = [...group.type.operations.values()];
 
-      // For interfaces that extend other interfaces, also collect operations from the source interfaces
-      // TypeSpec doesn't always automatically copy operations from extended interfaces,
-      // especially in versioning scenarios, so we need to manually collect them
-      if (group.type.kind === "Interface" && group.type.sourceInterfaces.length > 0) {
-        const operationsByName = new Map(operations.map((op) => [op.name, op]));
-        for (const sourceIface of group.type.sourceInterfaces) {
-          for (const [name, op] of sourceIface.operations) {
-            // Only add if not already present (prefer operations from derived interface)
-            if (!operationsByName.has(name)) {
-              operations.push(op);
-              operationsByName.set(name, op);
-            }
-          }
-        }
-      }
-
       // when there is explicitly `@operationGroup` or `@client`
       // operations under namespace or interface that are not decorated with `@operationGroup` or `@client`
       // should be placed in the first accessor client or operation group

packages/typespec-client-generator-core/src/clients.ts

@@ -1,13 +1,6 @@
-import {
-  createDiagnosticCollector,
-  Diagnostic,
-  getDoc,
-  getSummary,
-  listServices,
-} from "@typespec/compiler";
+import { createDiagnosticCollector, Diagnostic, getDoc, getSummary } from "@typespec/compiler";
 import { $ } from "@typespec/compiler/typekit";
 import { getServers, HttpServer } from "@typespec/http";
-import { getVersionDependencies } from "@typespec/versioning";
 import {
   getClientInitializationOptions,
   getClientNameOverride,
@@ -24,7 +17,6 @@ import {
   SdkEndpointParameter,
   SdkEndpointType,
   SdkHttpOperation,
-  SdkMethodParameter,
   SdkOperationGroup,
   SdkPathParameter,
   SdkServiceOperation,
@@ -199,14 +191,6 @@ export function createSdkClientType<TServiceOperation extends SdkServiceOperatio
       name = override;
     }
   }
-  if (!parent && client.kind === "SdkClient" && client.parent) {
-    const parentRaw = context.__rawClientsOperationGroupsCache?.get(client.parent) as
-      | SdkClient
-      | undefined;
-    parent = context.__clientTypesCache?.find((c) => c.__raw === parentRaw) as
-      | SdkClientType<TServiceOperation>
-      | undefined;
-  }
   const sdkClientType: SdkClientType<TServiceOperation> = {
     __raw: client,
     kind: "client",
@@ -230,8 +214,7 @@ export function createSdkClientType<TServiceOperation extends SdkServiceOperatio
   );
   addDefaultClientParameters(context, sdkClientType);
   // update initialization model properties
-  context.__clientTypesCache = context.__clientTypesCache || [];
-  context.__clientTypesCache.push(sdkClientType);
+
   return diagnostics.wrap(sdkClientType);
 }
 
@@ -257,48 +240,6 @@ function addDefaultClientParameters<
       if (apiVersionParam) break;
     }
   }
-
-  // Check for multi-service scenario with @useDependency
-  if (!apiVersionParam && client.__raw.kind === "SdkClient") {
-    const services = listServices(context.program);
-    if (services.length > 1 && client.__raw.type?.kind === "Namespace") {
-      // Check if this is a multi-service client with @useDependency
-      const versionDependencies = getVersionDependencies(context.program, client.__raw.type);
-      if (versionDependencies && versionDependencies.size > 0) {
-        // Create an API version parameter for multi-service clients with @useDependency
-        const stringType = context.program.checker.getStdType("string");
-
-        // Create a SdkMethodParameter for the API version
-        const apiVersionMethodParam: SdkMethodParameter = {
-          __raw: undefined,
-          kind: "method",
-          name: "apiVersion",
-          isGeneratedName: false,
-          doc: "The API version to use for the operation",
-          type: getSdkBuiltInType(context, stringType),
-          optional: false,
-          isApiVersionParam: true,
-          onClient: true,
-          apiVersions: context.getApiVersionsForType(client.__raw.type ?? client.__raw.service),
-          clientDefaultValue: undefined,
-          decorators: [],
-          crossLanguageDefinitionId: `${client.crossLanguageDefinitionId}.apiVersion`,
-          access: "public",
-          flatten: false,
-        };
-
-        // Add to cache
-        let clientParams = context.__clientParametersCache.get(client.__raw);
-        if (!clientParams) {
-          clientParams = [];
-          context.__clientParametersCache.set(client.__raw, clientParams);
-        }
-        clientParams.push(apiVersionMethodParam);
-        apiVersionParam = apiVersionMethodParam;
-      }
-    }
-  }
-
   if (apiVersionParam) {
     defaultClientParamters.push(apiVersionParam);
   }