Integrate OpenAI Codex into Claude Code: A Complete Plugin Guide

Overview

The Codex plugin for Claude Code lets you call OpenAI Codex directly from the Claude Code environment. It supports three main workflows: a standard Codex review, an adversarial (challenge) review that forces Codex to question the implementation, and a rescue mode that hands the task over to Codex for a second opinion.

Installation

/plugin marketplace add openai/codex-plugin-cc
/plugin install codex@openai-codex
/codex:setup

Prerequisites: a free ChatGPT subscription or an OpenAI API key, and Node.js 18.18 or newer. For more information see https://github.com/openai/codex-plugin-cc.

If the Codex CLI is not yet installed: npm install -g @openai/codex If the CLI is installed but not authenticated:

!codex login

Core Commands

/codex:review – Run a normal Codex code review.

/codex:adversarial-review – Run a guided, challenging review that asks Codex to critique the design and assumptions.

/codex:rescue – Transfer the current task to Codex for autonomous handling.

/codex:status – Query the status of a background job.

/codex:result – Retrieve the result of a completed background job.

/codex:cancel – Cancel a running background job.

Example of running a review in the background:

/codex:review --background
/codex:status
/codex:result

Recommended Usage Pattern

Run /codex:review for routine code changes.

Run /codex:adversarial-review for high‑risk changes, migrations, certification updates, infrastructure scripts, or any situation where hidden assumptions may exist.

Use /codex:rescue when the discussion reaches an impasse or you want Codex to take over the analysis.

How the Plugin Works

The plugin acts as a thin proxy to the locally installed Codex CLI and Codex application server. It reuses the same authentication tokens, configuration files, environment variables, and MCP settings that you already have for Codex, so no additional runtime is introduced.

Optional Review Gate

/codex:setup --enable-review-gate

Enabling the review gate forces Claude Code to wait for a Codex review to finish before exiting. Use with caution, as it can create a long Claude/Codex loop and quickly consume usage limits.

Summary

The Codex plugin provides a lightweight, command‑driven way to incorporate OpenAI Codex’s analysis capabilities into Claude Code without altering existing workflows. Install the plugin, run /codex:setup , set /codex:review as the default second review, and switch to /codex:adversarial-review or /codex:rescue for more demanding scenarios.