fix(http-client-python): avoid shell-quote leak in package-pprint-name

.chronus/changes/fix-pprint-name-shell-quote-leak-2026-7-6-14-56-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-python"
+---
+
+Fix Python SDK generation failure when `package-pprint-name` contains spaces. The shell-escaping quotes were baked into the option value and leaked into the Pyodide runtime, producing an invalid `setup.py` (e.g. `PACKAGE_PPRINT_NAME = ""Azure Web PubSub Chat Service""`) that `black` could not parse. Quoting is now applied only when building the native Python shell command.

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

@@ -42,18 +42,6 @@ function addDefaultOptions(sdkContext: PythonSdkContext) {
     // Explicitly set unbranded flavor when not azure
     (options as any).flavor = "unbranded";
   }
-
-  if (
-    options["package-pprint-name"] !== undefined &&
-    !options["package-pprint-name"].startsWith('"')
-  ) {
-    // Only add quotes for shell compatibility when NOT using emit-yaml-only mode
-    // (emit-yaml-only passes options via JSON config files, not shell)
-    const needsShellQuoting = !options["use-pyodide"] && !options["emit-yaml-only"];
-    options["package-pprint-name"] = needsShellQuoting
-      ? `"${options["package-pprint-name"]}"`
-      : `${options["package-pprint-name"]}`;
-  }
 }
 
 async function createPythonSdkContext(

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

@@ -16,6 +16,7 @@ import { blackExcludeDirs, PYGEN_WHEEL_FILENAME } from "./constants.js";
 import { saveCodeModelAsYaml } from "./external-process.js";
 import { PythonEmitterOptions, reportDiagnostic } from "./lib.js";
 import { runPython3 } from "./run-python3.js";
+import { quoteShellArg } from "./utils.js";
 
 export interface RunNodeEmitArgs {
   context: EmitContext<PythonEmitterOptions>;
@@ -106,7 +107,7 @@ export async function runNodeEmit({
   commandArgs["output-folder"] = outputDir;
   commandArgs["tsp-file"] = yamlPath;
   const commandFlags = Object.entries(commandArgs)
-    .map(([key, value]) => `--${key}=${value}`)
+    .map(([key, value]) => `--${key}=${quoteShellArg(String(value))}`)
     .join(" ");
   const command = `${venvPath} ${root}/eng/scripts/setup/run_tsp.py ${commandFlags}`;
   execSync(command);

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

@@ -268,6 +268,19 @@ export function capitalize(name: string): string {
   return name[0].toUpperCase() + name.slice(1);
 }
 
+/**
+ * Quotes a value so it can be safely embedded in a shell command line.
+ *
+ * The value is wrapped in double quotes (handling spaces and other separators)
+ * and any embedded double quotes are escaped. This quoting must only be applied
+ * when the value is passed through a shell (e.g. `execSync`); it must never be
+ * baked into the option value itself, otherwise the quotes leak into non-shell
+ * consumers such as the Pyodide runtime and end up in generated files.
+ */
+export function quoteShellArg(value: string): string {
+  return `"${value.replace(/\\/g, "\\\\").replace(/"/g, '\\"')}"`;
+}
+
 // Library namespaces that should not be used as client namespaces
 const LIB_NAMESPACE = [
   "azure.core",

packages/http-client-python/emitter/test/utils.test.ts

@@ -1,6 +1,6 @@
 import { strictEqual } from "assert";
 import { describe, it } from "vitest";
-import { camelToSnakeCase, md2Rst } from "../src/utils.js";
+import { camelToSnakeCase, md2Rst, quoteShellArg } from "../src/utils.js";
 
 describe("typespec-python: utils", () => {
   it("camelToSnakeCase", async () => {
@@ -27,4 +27,15 @@ describe("typespec-python: utils", () => {
     const des = "Format: <MajorVersion>.<MinorVersion>.<Patch>";
     strictEqual(md2Rst(des), "Format: <MajorVersion>.<MinorVersion>.<Patch>");
   });
+
+  it("quoteShellArg wraps values in double quotes without doubling existing content", async () => {
+    // Regression test for https://github.com/microsoft/typespec Python SDK generation failure
+    // where a package-pprint-name with spaces (e.g. "Azure Web PubSub Chat Service") got quotes
+    // baked into the option value and then leaked into the generated setup.py as doubled quotes.
+    strictEqual(quoteShellArg("Azure Web PubSub Chat Service"), '"Azure Web PubSub Chat Service"');
+    strictEqual(quoteShellArg("simple"), '"simple"');
+    strictEqual(quoteShellArg('has "quotes"'), '"has \\"quotes\\""');
+    strictEqual(quoteShellArg("trailing\\"), '"trailing\\\\"');
+    strictEqual(quoteShellArg('back\\slash "q"'), '"back\\\\slash \\"q\\""');
+  });
 });

packages/http-client-python/generator/pygen/preprocess/__init__.py

@@ -420,7 +420,6 @@ def add_body_param_type(
 
             code_model["types"].append(body_parameter["type"])
 
-
     def pad_reserved_words(self, name: str, pad_type: PadType, yaml_type: dict[str, Any]) -> str:
         # we want to pad hidden variables as well
         if not name: