Set codex SDK TypeScript originator (#4894)

## Summary
- ensure the TypeScript SDK sets CODEX_INTERNAL_ORIGINATOR_OVERRIDE to
codex_sdk_ts when spawning the Codex CLI
- extend the responses proxy test helper to capture request headers for
assertions
- add coverage that verifies Codex threads launched from the TypeScript
SDK send the codex_sdk_ts originator header

## Testing
- Not Run (not requested)


------
https://chatgpt.com/codex/tasks/task_i_68e561b125248320a487f129093d16e7

sdk/typescript/src/exec.ts

@@ -23,6 +23,9 @@ export type CodexExecArgs = {
   outputSchemaFile?: string;
 };
 
+const INTERNAL_ORIGINATOR_ENV = "CODEX_INTERNAL_ORIGINATOR_OVERRIDE";
+const TYPESCRIPT_SDK_ORIGINATOR = "codex_sdk_ts";
+
 export class CodexExec {
   private executablePath: string;
   constructor(executablePath: string | null = null) {
@@ -59,6 +62,9 @@ export class CodexExec {
     const env = {
       ...process.env,
     };
+    if (!env[INTERNAL_ORIGINATOR_ENV]) {
+      env[INTERNAL_ORIGINATOR_ENV] = TYPESCRIPT_SDK_ORIGINATOR;
+    }
     if (args.baseUrl) {
       env.OPENAI_BASE_URL = args.baseUrl;
     }

sdk/typescript/tests/responsesProxy.ts

@@ -54,6 +54,7 @@ export type ResponsesApiRequest = {
 export type RecordedRequest = {
   body: string;
   json: ResponsesApiRequest;
+  headers: http.IncomingHttpHeaders;
 };
 
 function formatSseEvent(event: SseEvent): string {
@@ -90,7 +91,7 @@ export async function startResponsesTestProxy(
       if (req.method === "POST" && req.url === "/responses") {
         const body = await readRequestBody(req);
         const json = JSON.parse(body);
-        requests.push({ body, json });
+        requests.push({ body, json, headers: { ...req.headers } });
 
         const status = options.statusCode ?? 200;
         res.statusCode = status;

sdk/typescript/tests/run.test.ts

@@ -345,6 +345,30 @@ describe("Codex", () => {
       await close();
     }
   });
+
+  it("sets the codex sdk originator header", async () => {
+    const { url, close, requests } = await startResponsesTestProxy({
+      statusCode: 200,
+      responseBodies: [sse(responseStarted(), assistantMessage("Hi!"), responseCompleted())],
+    });
+
+    try {
+      const client = new Codex({ codexPathOverride: codexExecPath, baseUrl: url, apiKey: "test" });
+
+      const thread = client.startThread();
+      await thread.run("Hello, originator!");
+
+      expect(requests.length).toBeGreaterThan(0);
+      const originatorHeader = requests[0]!.headers["originator"];
+      if (Array.isArray(originatorHeader)) {
+        expect(originatorHeader).toContain("codex_sdk_ts");
+      } else {
+        expect(originatorHeader).toBe("codex_sdk_ts");
+      }
+    } finally {
+      await close();
+    }
+  });
   it("throws ThreadRunError on turn failures", async () => {
     const { url, close } = await startResponsesTestProxy({
       statusCode: 200,