[python] let client options on child clients override parent client (#9776)

fixes #9757

---------

Co-authored-by: iscai-msft <isabellavcai@gmail.com>

Author: iscai-msft

.chronus/changes/python-clientOptionInterface-2026-1-23-17-13-8.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-python"
+---
+
+Allow client options on child clients to override parent clients

packages/http-client-python/emitter/src/code-model.ts

@@ -39,7 +39,7 @@ function emitBasicMethod<TServiceOperation extends SdkServiceOperation>(
   context: PythonSdkContext,
   rootClient: SdkClientType<TServiceOperation>,
   method: SdkBasicServiceMethod<TServiceOperation>,
-  operationGroupName: string,
+  operationGroup: SdkClientType<TServiceOperation>,
   serviceApiVersions: string[],
 ): Record<string, any>[] {
   if (method.operation.kind !== "http")
@@ -50,7 +50,7 @@ function emitBasicMethod<TServiceOperation extends SdkServiceOperation>(
         context,
         rootClient,
         method,
-        operationGroupName,
+        operationGroup.name,
         serviceApiVersions,
       );
     default:
@@ -62,14 +62,20 @@ function emitLroMethod<TServiceOperation extends SdkServiceOperation>(
   context: PythonSdkContext,
   rootClient: SdkClientType<TServiceOperation>,
   method: SdkLroServiceMethod<TServiceOperation>,
-  operationGroupName: string,
+  operationGroup: SdkClientType<TServiceOperation>,
   serviceApiVersions: string[],
 ): Record<string, any>[] {
   if (method.operation.kind !== "http")
     throw new Error("We only support HTTP operations right now");
   switch (method.operation.kind) {
     case "http":
-      return emitLroHttpMethod(context, rootClient, method, operationGroupName, serviceApiVersions);
+      return emitLroHttpMethod(
+        context,
+        rootClient,
+        method,
+        operationGroup.name,
+        serviceApiVersions,
+      );
     default:
       throw new Error("We only support HTTP operations right now");
   }
@@ -79,7 +85,7 @@ function emitPagingMethod<TServiceOperation extends SdkServiceOperation>(
   context: PythonSdkContext,
   rootClient: SdkClientType<TServiceOperation>,
   method: SdkPagingServiceMethod<TServiceOperation>,
-  operationGroupName: string,
+  operationGroup: SdkClientType<TServiceOperation>,
   serviceApiVersions: string[],
 ): Record<string, any>[] {
   if (method.operation.kind !== "http")
@@ -90,7 +96,7 @@ function emitPagingMethod<TServiceOperation extends SdkServiceOperation>(
         context,
         rootClient,
         method,
-        operationGroupName,
+        operationGroup.name,
         serviceApiVersions,
       );
     default:
@@ -102,7 +108,7 @@ function emitLroPagingMethod<TServiceOperation extends SdkServiceOperation>(
   context: PythonSdkContext,
   rootClient: SdkClientType<TServiceOperation>,
   method: SdkLroPagingServiceMethod<TServiceOperation>,
-  operationGroupName: string,
+  operationGroup: SdkClientType<TServiceOperation>,
   serviceApiVersions: string[],
 ): Record<string, any>[] {
   if (method.operation.kind !== "http")
@@ -113,7 +119,7 @@ function emitLroPagingMethod<TServiceOperation extends SdkServiceOperation>(
         context,
         rootClient,
         method,
-        operationGroupName,
+        operationGroup.name,
         serviceApiVersions,
       );
     default:
@@ -183,25 +189,19 @@ function emitMethodParameter(
 function emitMethod<TServiceOperation extends SdkServiceOperation>(
   context: PythonSdkContext,
   rootClient: SdkClientType<TServiceOperation>,
+  operationGroup: SdkClientType<TServiceOperation>,
   method: SdkServiceMethod<TServiceOperation>,
-  operationGroupName: string,
   serviceApiVersions: string[],
 ): Record<string, any>[] {
   switch (method.kind) {
     case "basic":
-      return emitBasicMethod(context, rootClient, method, operationGroupName, serviceApiVersions);
+      return emitBasicMethod(context, rootClient, method, operationGroup, serviceApiVersions);
     case "lro":
-      return emitLroMethod(context, rootClient, method, operationGroupName, serviceApiVersions);
+      return emitLroMethod(context, rootClient, method, operationGroup, serviceApiVersions);
     case "paging":
-      return emitPagingMethod(context, rootClient, method, operationGroupName, serviceApiVersions);
+      return emitPagingMethod(context, rootClient, method, operationGroup, serviceApiVersions);
     default:
-      return emitLroPagingMethod(
-        context,
-        rootClient,
-        method,
-        operationGroupName,
-        serviceApiVersions,
-      );
+      return emitLroPagingMethod(context, rootClient, method, operationGroup, serviceApiVersions);
   }
 }
 
@@ -218,11 +218,17 @@ function emitOperationGroups<TServiceOperation extends SdkServiceOperation>(
 
   for (const operationGroup of client.children ?? []) {
     const name = `${prefix}${operationGroup.name}`;
+    const operationGroupWithPrefixedName = {
+      ...operationGroup,
+      name,
+    } as SdkClientType<TServiceOperation>;
     let operations: Record<string, any>[] = [];
     const apiVersions =
       serviceApiVersions.length > 0 ? serviceApiVersions : operationGroup.apiVersions;
     for (const method of operationGroup.methods) {
-      operations = operations.concat(emitMethod(context, rootClient, method, name, apiVersions));
+      operations = operations.concat(
+        emitMethod(context, rootClient, operationGroupWithPrefixedName, method, apiVersions),
+      );
     }
     operationGroups.push({
       name: name,
@@ -236,10 +242,11 @@ function emitOperationGroups<TServiceOperation extends SdkServiceOperation>(
 
   // root client should deal with mixin operation group
   if (prefix === "") {
+    const mixinGroup = { ...client, name: "" } as SdkClientType<TServiceOperation>;
     let operations: Record<string, any>[] = [];
     for (const method of client.methods) {
       operations = operations.concat(
-        emitMethod(context, rootClient, method, "", serviceApiVersions),
+        emitMethod(context, rootClient, mixinGroup, method, serviceApiVersions),
       );
     }
     if (operations.length > 0) {

packages/http-client-python/emitter/src/http.ts

@@ -379,7 +379,16 @@ function emitHttpOperation(
   for (const exception of operation.exceptions) {
     exceptions.push(emitHttpResponse(context, exception.statusCodes, exception, undefined, true)!);
   }
-  const includeRootSlash = getClientOptions(rootClient, "includeRootSlash") !== false;
+  // Walk up the client hierarchy to find the option, allowing sub-clients to
+  // override values set on the root client.
+  let includeRootSlashOption: unknown;
+  let current: SdkClientType<SdkHttpOperation> | undefined = rootClient;
+  while (current) {
+    includeRootSlashOption = getClientOptions(current, "includeRootSlash");
+    if (includeRootSlashOption !== undefined) break;
+    current = current.parent;
+  }
+  const includeRootSlash = includeRootSlashOption !== false;
 
   const result = {
     url: includeRootSlash ? operation.path : operation.path.replace(/^\//, ""),