posit-codex-gateway

Love Codex models, hate API prices? ☀️ 🌍 🌙 Use your existing ChatGPT/Codex subscription sign-in with RStudio Posit Assistant.

posit-codex-gateway is a small local bridge between RStudio and the published @carl-stone/openai-oauth runtime. It signs in with your ChatGPT account and adjusts Posit Assistant requests so they work with the Codex Responses service.

Unofficial community project. This project is not affiliated with, endorsed by, or supported by Posit or OpenAI.

Before you start

You need:

• Node.js 20 or newer;
• RStudio with Posit Assistant 0.9.8 (RStudio protocol 11.0); and
• a ChatGPT/Codex Plus or Pro subscription.

This gateway uses your ChatGPT/Codex sign-in. You do not need an OpenAI API key.

Quick start

With Node.js installed, run these commands in a Terminal window:

npm install --global posit-codex-gateway
posit-codex-gateway login
posit-codex-gateway

The last command keeps the gateway running in the foreground. Leave that Terminal window open while you use Posit Assistant.

Or, to run it in the background instead, use:

posit-codex-gateway --detach

Connect Posit Assistant

In the Posit Assistant pane in RStudio, select the gear > Configure LLM providers > OpenAI. Change the Base URL and API key to:

| Setting | Value | | --- | --- | | Base URL | http://127.0.0.1:10532/v1 | | API key | Leave empty |

The gateway supplies all models available through your ChatGPT/Codex account.

Start, check, and stop the gateway

These commands are useful when the gateway is running in the background:

posit-codex-gateway status
posit-codex-gateway logs --follow
posit-codex-gateway stop

Run posit-codex-gateway again to start it in the foreground after stopping it. The default port is 10532, which matches the Posit Assistant URL above. You can choose another port with, for example, --port 10533; if you do, change the provider's base URL to match.

What you need to know

The gateway connects Posit Assistant to your ChatGPT/Codex session and handles the request-format differences automatically. There is nothing special to configure in Posit Assistant beyond the local base URL shown above.

Messages, images, reasoning, tools, tool calls and results, and streaming responses are supported. The gateway keeps a temporary, in-memory record of recent Responses items so Posit Assistant can continue after a tool call. This record is not written to disk and disappears when the gateway stops.

Sign-in, model discovery, chat and image requests, OAuth refresh, and the connection to ChatGPT/Codex are provided by the published OAuth runtime.

Supported versions

| Gateway | Posit Assistant | RStudio protocol | OAuth runtime | Responses adapter | | --- | --- | --- | --- | --- | | 0.1.x | 0.9.8 | 11.0 | @carl-stone/openai-oauth 2.0.0-memory.2 | v1 |

The project checks that its requests still match Codex automatically in CI.

Troubleshooting

Run the read-only diagnostic report with:

posit-codex-gateway doctor

It reports the installed gateway, Posit Assistant, and openai-oauth versions and whether the local gateway is healthy. It does not read conversations or credentials.

Common fixes:

• RStudio cannot connect: make sure the gateway is running and the base URL is exactly http://127.0.0.1:10532/v1.
• The port is busy: stop the other process, or start with posit-codex-gateway --port <number> and update the base URL.
• Sign-in fails: run posit-codex-gateway login again, then restart the gateway.
• A conversation fails after restarting the gateway: start a new Posit Assistant conversation. Temporary tool-continuation state is cleared when the gateway stops.
• The background gateway isn't working: run status, inspect logs, then use stop before starting it again.

Privacy and network behavior

By default, the gateway listens only on your computer at 127.0.0.1. It uses the same host behavior as openai-oauth; an explicit --host can make it reachable from other interfaces, so use that option only when you intend to.

OAuth credentials and upstream transport are handled by the published OAuth runtime. Recent Responses items are held only in the running process, with default limits of 256 response-history entries and 2,000 items. They are never persisted by the gateway and are discarded when it stops or restarts. Diagnostics are off by default. If enabled with --diagnostics, they contain metadata only: request ID, model, schema-only removed-field patterns, cache breakpoint count, status, duration, and safely available token counts. Prompts, conversation content, tool arguments/results, credentials, headers, auth material, and reasoning content are not logged.

Advanced CLI options

The gateway accepts the same public commands and options as its openai-oauth runtime, including login, --host, --port, --models, --codex-version, --base-url, OAuth overrides, --no-open, login timeout, --detach, status, logs, stop, --responses-state, --responses-max-responses, and --responses-max-items.

There are two intentional defaults for Posit Assistant: port 10532 and process-local Responses memory. You can explicitly override either default, although --responses-state stateless will prevent Posit tool-call continuations from working. doctor and --diagnostics are gateway-specific additions.

Development

npm install
npm run verify
npm run check:contract
npm pack --dry-run

CI runs tests, typechecking, linting, and the TypeScript build. A separate scheduled/manual workflow checks for Codex contract drift. Dependabot watches the npm and GitHub Actions dependencies.

Credits and license

This project uses @carl-stone/openai-oauth, a published fork of Evan Zhou's openai-oauth. The dependency ships its own Apache-2.0 license and notice; this repository's required attribution is included in NOTICE.

The original gateway code in this repository is copyright Carl Stone and is licensed under Apache-2.0. See LICENSE.