Codex SDK (gateway)

Route Codex SDK model calls through the Respan gateway when your Respan key has access to the Codex-compatible endpoint. This page only covers gateway routing and does not install or configure tracing instrumentation.

Setup

Install packages

$ npm install @openai/codex-sdk

Set environment variables

$ export RESPAN_API_KEY="YOUR_RESPAN_API_KEY"
$ export RESPAN_BASE_URL="https://api.respan.ai/api"

No separate provider key is needed when the gateway route is enabled for your Respan key.

Point Codex SDK to the Respan gateway

1 import { Codex } from "@openai/codex-sdk";
2 
3 const codex = new Codex({
4   apiKey: process.env.RESPAN_API_KEY,
5   baseUrl: process.env.RESPAN_BASE_URL ?? "https://api.respan.ai/api",
6   env: {
7     ...process.env,
8     CODEX_API_KEY: process.env.RESPAN_API_KEY!,
9     OPENAI_API_KEY: process.env.RESPAN_API_KEY!,
10   },
11 });
12 
13 const thread = codex.startThread({
14   workingDirectory: process.cwd(),
15   skipGitRepoCheck: true,
16   sandboxMode: "read-only",
17   approvalPolicy: "never",
18   model: "gpt-5.5",
19 });
20 
21 const result = await thread.run("Explain gateway routing in one short sentence.");
22 console.log(result.finalResponse);

Codex SDK routing depends on the SDK’s Codex-compatible API path. If your key is not enabled for that route, configure gateway access before using this setup.

Switch models

Change the model option on a Codex thread to use another model supported by your gateway configuration.

1 const thread = codex.startThread({
2   workingDirectory: process.cwd(),
3   skipGitRepoCheck: true,
4   sandboxMode: "read-only",
5   approvalPolicy: "never",
6   model: "claude-sonnet-4-5-20250929",
7 });

See the full model list.