Codex Setup Guide: From Environment Configuration to Core Features Explained

Introduction

Codex, OpenAI's AI programming tool, is becoming a new favorite among developers thanks to its multi-task parallelism, sandbox security mechanisms, and user-friendly workspace management. The current AI coding tool market features diverse competition — Anthropic's Claude Code is known for its powerful code comprehension and long context handling, GitHub Copilot excels at code completion with deep IDE integration, and Cursor embeds AI capabilities directly into the editing experience as an AI-native editor. Codex positions itself between an Agent and an IDE, emphasizing multi-task parallelism and out-of-the-box security mechanisms, aiming to strike a balance between usability and functionality. This article provides a comprehensive guide to Codex — from prerequisite setup and installation to core feature modules — helping beginners get started quickly.

Prerequisite Environment Setup

Three Essential Software Tools

Before installing Codex, you need to prepare three prerequisite tools:

• Git: A version control and collaboration tool that nearly all AI development tools and agents (such as Hermes, Claude Code, etc.) depend on. Git is a distributed version control system developed by Linus Torvalds, the creator of Linux, in 2005. Unlike centralized version control systems (such as SVN), Git gives every developer a complete local copy of the repository, making offline work and branch management extremely efficient. In the AI coding tool ecosystem, Git's importance lies in the fact that AI Agents rely on it to track code changes, manage project history, enable code rollbacks, and more. Platforms like GitHub and GitLab are built on Git, forming the collaborative infrastructure of modern software development.
• Node.js: Handles dependency package installation. Codex has no strict version requirements — just install the latest version. Node.js is a JavaScript runtime environment built on Chrome's V8 engine, enabling JavaScript to run on the server side outside of browsers. Many modern development tools (including Codex) use npm (Node Package Manager) to manage project dependencies, which is why Node.js is a required prerequisite.
• VS Code: Not strictly required, but strongly recommended. Codex itself doesn't provide code editing capabilities — when you need to make detailed modifications to AI-generated code, you still need a traditional editor. VS Code, developed by Microsoft, has become the world's most popular code editor thanks to its rich extension ecosystem and lightweight architecture.

Verifying Your Installation

All three tools have straightforward installation processes. After installation, you can verify them as follows:

Press Windows + R to open the Run dialog, type CMD, and in the command line enter node -v — seeing a version number confirms Node.js is installed successfully. For Git, enter git --version to verify.

VS Code defaults to an English interface after installation. You can search for "Chinese" in the Extensions panel on the left to install the Chinese language pack, then restart to switch to Chinese.

Codex Installation Process

Download and Installation Steps

Installing Codex is equally simple: visit the official website and download the Windows or Mac version for your system. Note that what you download is not an installer but a downloader — it connects to the Microsoft Store to download and install approximately 400MB.

Important Note: The entire process — accessing the official website, downloading, installing, and using Codex — requires a VPN or proxy connection. Many users get stuck on the loading screen and can't proceed, and the root cause is almost always a network connectivity issue.

First-Time Setup

When you first open Codex, a "Set up sandbox" button appears at the top of the interface. Click it to complete sandbox initialization. The sandbox is Codex's core permission management mechanism, which we'll explain in detail later.

Workspaces and Multi-Task Management

Creating a Workspace

A major differentiator between Codex and other AI coding tools is its support for running multiple tasks simultaneously, with a very user-friendly task list management interface.

Creating a workspace is simple: create a project folder locally and drag it into Codex's left panel. You can also add projects via the "Add new project" button below the dialog box.

Multi-Task Parallel Operations

Select the corresponding project in the dialog box and issue your task. Use Ctrl + N (or Command + N on Mac) to create a new conversation window, allowing you to execute multiple tasks across different projects simultaneously.

Tasks have three status indicators:

• In Progress: Icon spins continuously
• Awaiting Approval: Requires user authorization (e.g., creating files, downloading resources)
• Completed: Displays a blue dot

If you choose "No project" for a conversation, the content goes to the "Conversations" area in the lower left and isn't associated with any project.

Core Feature Modules Explained

Search and Conversation Management

History Search: Click the search button on the left or press Ctrl + G to open search, which lets you search through all past conversations. Note that only conversation titles are searchable — content is not indexed.

Conversation Renaming: Double-click a conversation title to rename it. It's recommended to add special identifiers to important conversations for easier retrieval later.

Archive Feature: When conversations pile up, click the archive button next to a conversation to archive it. Archived conversations disappear from the list and move to "Settings > Archived Conversations." You can unarchive them at any time.

Permission Management and Sandbox Mechanism

Codex's permission control revolves around the sandbox, which treats the current project folder as a sandboxed environment. A sandbox is a core concept in computer security, originating from OS isolation technology. The basic principle is to create a restricted execution environment for programs — the program can only access authorized resources within that environment and cannot reach external systems. Common sandbox implementations include containerization technologies (such as Docker), virtual machine isolation, OS-level namespace isolation (such as Linux namespaces and cgroups), and file system permission controls.

Codex provides three permission levels:

Default Permissions: Read and write access to files within the sandbox, but no ability to modify files outside the sandbox, and no internet access. These restrictions are enforced at the operating system level, not the model level, ensuring high security. This means that even if the AI model is targeted by a prompt injection attack, it cannot break through system-level permission restrictions — a security approach that is orders of magnitude stronger than relying solely on model self-restraint. Operations requiring elevated permissions trigger manual review.

Auto Review (Recommended): A lightweight permission management model is invoked to perform security reviews on privilege escalation operations. Low-risk operations are automatically approved, while high-risk operations (such as deleting files) still require manual confirmation. This effectively eliminates the hassle of frequent authorization prompts. This design borrows from the UAC (User Account Control) concept in operating systems, balancing security with convenience.

Full Access: Ignores sandbox restrictions entirely — can access and modify external files, connect to the internet, etc. This is a dangerous mode; a confirmation dialog appears when enabling it for the first time.

Compared to Claude Code, Codex's sandbox mechanism is more convenient — it comes built-in by default and requires no manual configuration.

Context Management Strategy

Click the progress bar icon in the dialog box to view context usage information (used/total). The context window is one of the core parameters of large language models, determining how much information the model can "remember" in a single interaction. A token is the basic unit of text processing for the model — in English, one token corresponds to roughly 4 characters or 0.75 words; in Chinese, one character typically maps to 1-2 tokens.

When the context exceeds its limit, Codex automatically compresses conversation history to free up space. You can also manually trigger compression by entering a slash command.

Best Practice: In real-world development, clearing is better than compressing. No matter how much you compress, residual historical information remains, distracting the model's focus and increasing token consumption. While compression frees up space, it leads to information loss and semantic ambiguity — residual compressed information may contain outdated context, causing the model to produce outputs inconsistent with the current task. Meanwhile, processing this redundant information with every interaction adds unnecessary token consumption and response latency. It's recommended to open a new conversation window for each new task.

Model Selection and Speed Configuration

Model selection offers three dimensions:

• Intelligence Level: Low / Medium / High / Ultra High — choose based on task complexity, with Medium as the default. This setting essentially corresponds to different model sizes or reasoning depth configurations. Low intelligence is suitable for simple tasks like code formatting and variable renaming, while Ultra High is better for complex architectural design, algorithm optimization, and other deep-reasoning scenarios.
• Model Version: Supports GPT-5.5, 5.4, 5.4 mini, 5.3, etc. — using the latest model is recommended. Different versions vary in code generation quality, context comprehension, and response speed. Mini versions typically maintain core capabilities while significantly reducing computational costs.
• Speed Mode: Standard (normal token consumption) and Fast (1.5x speed, 2x token consumption). Fast mode reduces response time by allocating more parallel computing resources, making it suitable for time-sensitive development scenarios, but it depletes your quota more quickly.

Quota Management and Pricing Plans

Under "Settings," you can view your remaining quota across two dimensions:

• 5-Hour Limit: Resets every 5 hours
• Weekly Limit: Resets every week

Once either quota is exhausted, you can no longer use the tool. This dual-quota design prevents excessive short-term usage from overloading servers while controlling overall costs through weekly limits. Pricing plans start at $8, which is generally sufficient for everyday use; heavy users can opt for the $20 plan. Compared to Claude Code (which typically requires higher subscription fees), Codex's pricing is more accessible, lowering the barrier to entry for AI coding tools.

Conclusion

As OpenAI's AI programming tool, Codex excels in multi-task parallelism, sandbox security mechanisms, and workspace management. Its installation and configuration process is simple and intuitive, and its permission management design is both granular and user-friendly. For developers, it's recommended to use the "Auto Review" permission mode combined with a "new task, new conversation" workflow for the best development experience. As AI coding tools evolve from code completion toward autonomous agents, Codex represents a product philosophy that prioritizes the balance between security and usability — one worth watching as it continues to iterate.