How to Set Up Codex for Coding Workflows

TL;DR

Install Codex CLI with npm or Homebrew, add the official OpenAI extension to a VS Code-based IDE, then sign in with your ChatGPT Enterprise work account. Use AGENTS.md to supply persistent project instructions, configure the environment with config.toml, and apply clear prompting patterns before expanding into MCP, cloud tasks, headless mode, or SDK integrations.

Transcript

Hi, welcome to today's getting started with codec session. I'm Derek >> and I'm Charlie >> and we work with customers to help them get onboarded to Codeex. It's a really exciting time in the AI coding space and it's quickly changing how developers work. So, Codeex is OpenAI's coding agent that developers can use across different surfaces. And we've... Read More

Key Insights

• Codex is OpenAI’s coding agent for working across several development surfaces, including a lightweight terminal CLI, a graphical extension for VS Code-based IDEs, remote cloud environments, and a headless SDK mode designed for more advanced programmatic use.
• Codex cloud environments can run multiple background tasks in parallel, even while a laptop is closed. The session presents this capability as useful for asynchronous work such as code review and for starting tasks from a mobile phone while away from a primary development machine.
• Codex can participate in team workflows through cloud code reviews, Slack mentions, and custom SDK integrations. A Slack mention can provide the surrounding conversation thread as context, while an SDK integration can run Codex programmatically inside a team’s own containers and return structured code output.
• Codex CLI can be installed with Homebrew or npm, with npm presented as the suggested method for receiving current releases. Users can also inspect binary releases on GitHub, consult the published changelog, and use the session banner to notice when an updated CLI version is available.
• The official Codex IDE extension works with VS Code-based editors and should be identified as the extension made by OpenAI. Users can choose between pre-release and release versions, inspect the installed version, and enable automatic updates to receive newly shipped extension changes.
• Codex authentication can begin from either the IDE extension or the CLI. Running codex login opens a sign-in page where an enterprise user can enter a work email and complete any internal SSO flow, after which access applies to both the CLI and IDE extension.
• AGENTS.md is a lightweight project guide that Codex loads automatically when it exists in the directory where a session starts. It compensates for the lack of retained context between sessions by repeatedly supplying essential project background, commands, structure, conventions, tools, and workflows.
• AGENTS.md instructions can be organized at multiple scopes. A global file in the Codex home folder can define recurring preferences, a repository-root file can establish project-wide context, and additional files in subdirectories can provide focused guidance when Codex works inside particular services or components.

Questions & Answers

Q: How do you install Codex CLI and its IDE extension?

Install Codex CLI using npm or Homebrew. The walkthrough identifies npm as the suggested option because releases are shipped frequently and it helps users stay current. For graphical IDE use, open the extensions area of a VS Code-based editor, search for OpenAI Codex, confirm that the extension is the official one made by OpenAI, and install it.

Q: How do you sign in to Codex with an enterprise account?

Run codex login in the CLI or select the sign-in option shown when the IDE extension first opens. Either route leads to a sign-in page where you use your ChatGPT Enterprise work email and, when applicable, complete the organization’s internal SSO process. Finishing authentication through either interface signs you in for both local CLI and IDE extension use.

Q: What does the Codex slash status command show?

The slash status command provides a high-level view of the current Codex session. The walkthrough says it displays the active model, working directory, sandbox mode, approval policy, remaining context window, account information, and session ID. This makes it useful for checking the environment and configuration under which Codex is currently operating before or during repository work.

Q: What is AGENTS.md and why should a project use it?

AGENTS.md is a lightweight README-style file that gives Codex the background required to work effectively in a project. Coding agents do not retain project context between separate sessions, so Codex automatically loads this file when it is present in the starting directory. The file can repeatedly provide project structure, commands, tools, conventions, and implementation guidance without manual re-entry.

Q: How do you create an AGENTS.md file for Codex?

Use the slash init command in Codex CLI to generate an AGENTS.md file in the directory where you are working, or create the file yourself. A repository-root file can supply broad project instructions, while files inside subdirectories can describe individual services. A separate global AGENTS.md in the Codex home folder can hold preferences that should apply across projects.

Q: What information should an AGENTS.md file contain?

An AGENTS.md file commonly includes a project overview, repository structure, pointers to important files, build instructions, and test commands. It can also identify helpful command-line tools such as the GitHub CLI, describe MCP servers used by the project, outline the preferred workflow for implementing a feature, and link to separate files containing task-specific guidance for progressive discovery.

Q: How can Codex fit into a team development workflow?

Codex can review pull requests in a cloud environment, leave comments, and identify critical bugs or issues before code reaches production. Teams can also mention Codex in Slack so it receives the surrounding discussion, implements the requested work, and returns a pull request. For custom workflows, the SDK can run Codex programmatically in team-managed containers and produce structured code output.

Q: When should developers use Codex cloud or headless mode?

Codex cloud is suited to remote and asynchronous tasks because it can run multiple jobs in parallel in the background, including while the user’s laptop is closed. The session specifically connects cloud use with code review and mobile work. Headless SDK mode is intended for more advanced programmability, including custom integrations that run Codex in a team’s own containers and return structured output.

Summary & Key Takeaways

• Codex is OpenAI’s coding agent for delegating routine and time-consuming development work while developers focus on complex challenges such as design and architecture. It is available through a terminal CLI, a VS Code-based IDE extension, cloud environments for remote tasks, and a headless SDK mode for programmatic integrations and structured output.

• Initial setup involves installing the CLI through npm or Homebrew, installing the official OpenAI extension in a VS Code-based IDE, and signing in with a ChatGPT Enterprise work account. The session demonstrates cloning the open-source agents.md repository, entering its directory, installing npm dependencies, and running the project locally with npm run dev.

• AGENTS.md gives Codex project context that loads automatically at the beginning of sessions. It can describe project structure, build and test commands, useful tools, implementation workflows, and links to task-specific guidance. Files may be global, repository-level, or placed in subdirectories to provide instructions tailored to individual services or components.