# Build Hour: Codex

Source: https://www.youtube.com/watch?v=WvMqA4Xwx_k
Recap page: https://rapidrecap.app/video/WvMqA4Xwx_k
Generated: 2025-09-08T18:02:33.891+00:00

---
## Quick Overview

OpenAI's Codex, a coding agent that helps write, review, and ship code faster, has evolved significantly with new features like an IDE extension, a revamped CLI, and code review capabilities in GitHub, all accessible through a unified ChatGPT account, offering a seamless experience across local and cloud environments.

**Key Points:**
- Codex, OpenAI's coding agent, has seen significant updates including a new IDE extension and a revamped CLI for enhanced user experience.
- Codex now offers code review on GitHub, allowing users to review their own code and Codex's generated code, improving collaboration and quality.
- Tasks can be triggered as inspiration strikes, accessible via the mobile app or the Codex web interface, offering flexibility for developers.
- Codex environments can be set up to run locally or in the cloud, providing users with options based on their workflow and needs.
- The tool leverages GPT-5 for improved code quality, reasoning capabilities, and expanded features, making it a powerful assistant for various coding tasks.
- Users can now integrate Codex with their existing development workflows, including Git, for a more streamlined experience.
- OpenAI's commitment to continuous improvement ensures Codex remains a valuable tool for developers scaling their companies with AI APIs and models.

![Screenshot at 00:00: Title slide of the "OpenAI Build Hours" episode on "Codex", featuring the speakers Dominik Kundel and Pranav Deshpande.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-00-00.png)

**Context:** This video, part of the OpenAI Build Hours series, introduces and demonstrates Codex, an AI-powered coding agent designed to assist developers. It covers recent updates and best practices for using Codex, highlighting its integration into IDEs, CLI, and GitHub for a comprehensive coding workflow. The session emphasizes how Codex aims to empower users to scale their companies using OpenAI APIs and models.

## Detailed Analysis

OpenAI's Codex is an AI-powered coding agent that assists developers by writing, reviewing, and shipping code more efficiently. The agent has evolved with several new features, including a dedicated IDE extension and a revamped Command Line Interface (CLI) for improved user experience. Codex can be used locally on a developer's machine or in the cloud, offering flexibility. The presentation highlights how Codex leverages GPT-5 for enhanced code quality, reasoning, and feature expansion, enabling users to scale their companies using OpenAI APIs and models. Key updates include the ability to pair Codex locally using the IDE extension, delegate tasks to Codex in the cloud, perform code reviews directly on GitHub, and utilize Codex from a mobile app or web interface. The video demonstrates how to set up Codex environments, run tasks, and leverage its capabilities for various coding needs, such as writing tests, outlining plans in Markdown for complex tasks, and reviewing code. The importance of structuring code and projects for collaboration is emphasized, along with the benefit of having tests or other mechanisms to check Codex's work. The presenters also share resources for further learning, including Codex documentation, Agents.md, the Codex CLI, and the Build Hour repository.

### Introduction

- Overview of Codex
- Purpose: To empower developers with best practices, tools, and AI expertise to scale their company using OpenAI APIs & models.

### Codex Updates

- Introduced IDE extension, revamped CLI, GitHub code review
- Features: Local/cloud execution, Python code integration, multiple agent support

### Best Practices

- Structure code for collaboration
- Get into an architect/EM mindset
- Delegate tasks
- Have tests/other ways to check work
- Use Codex to outline plans as Markdown
- Use Codex code review on GitHub
- Trigger tasks as inspiration hits

### Live Walkthrough

- Demonstrates pairing Codex locally via IDE extension
- Delegating to cloud
- Code review on GitHub
- Using Codex from phone

### How Codex Works Today

- Two dimensions - where you use Codex (IDE, Terminal, GitHub, Web, Mobile) and where Codex runs (Locally on machine via CLI/IDE extension, Remotely in cloud sandbox)

### Resources

- Links to Codex docs, Agents.md, Codex CLI, Build Hour Repo

![Screenshot at 00:00: Title slide of the "OpenAI Build Hours" episode on "Codex", featuring the speakers Dominik Kundel and Pranav Deshpande.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-00-00.png)
![Screenshot at 00:12: Slide detailing the purpose of Build Hours: to empower users with best practices, tools, and AI expertise to scale their company using OpenAI APIs & models.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-00-12.png)
![Screenshot at 00:38: Agenda slide outlining the video's structure: Codex Updates, Live Walkthrough, Best Practices, and Q&A.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-00-38.png)
![Screenshot at 00:49: Mention of the recent launch of GPT-5, highlighting its advanced coding capabilities.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-00-49.png)
![Screenshot at 01:14: Discussion of recent improvements to Codex, including a new IDE extension and revamped CLI.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-01-14.png)
![Screenshot at 01:35: Explanation of how Codex works, emphasizing its ability to run locally or in the cloud.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-01-35.png)
![Screenshot at 01:58: Title slide for "Codex Updates", introducing new features and improvements.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-01-58.png)
![Screenshot at 02:26: Overview of Codex's initial release in April 2025 and its evolution, including the Codex CLI.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-02-26.png)
![Screenshot at 03:15: Slide showcasing "Codex: Now" with the tagline "One agent for everywhere you code".](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-03-15.png)
![Screenshot at 03:40: New features highlighted: Codex IDE extension, Revamped Codex CLI, NEW: Code review in GitHub, NEW: Local \<-\> cloud handoffs linked to ChatGPT account.](https://ss.rapidrecap.app/screens/WvMqA4Xwx_k/00-03-40.png)