Codex Beginner's Guide: 12 Core Use Cases from Installation to Mastery

OpenAI's Codex client is becoming a dark horse in the AI tool space. Compared to competitors like Claude Code, Codex offers richer features, more generous usage limits, and is extremely beginner-friendly—no complex configuration needed, no risk of throttling or rate limiting. This article systematically covers Codex's 12 core use cases from installation to advanced techniques, helping you quickly master this AI Agent tool that users describe as "impossible to go back from."

Codex Installation and Basic Interface Configuration

Quick Installation of the Codex Client

The Codex installation process is very straightforward. After visiting the official website, the system automatically detects your operating system (supporting Mac and Windows) and provides the corresponding installer. Mac users simply drag the app into the Applications folder, while Windows users follow the wizard step by step. After installation, log in with your GPT account—existing ChatGPT Plus subscribers can start using it immediately.

Note that the Windows version does not currently support the "computer control" feature, but all other functions are essentially the same as the Mac version.

Three-Panel Interface Layout

Codex uses a classic three-panel layout:

• Left navigation bar: Contains entries for new conversations, search, plugins, automation, projects, conversation history, and settings (where you can switch to Simplified Chinese)
• Center conversation area: The core area for entering instructions, supporting image and PDF attachments, model switching, permission adjustment, and context usage viewing
• Right preview area: Codex's "deliverables" zone, displaying document previews, web previews, search sources, modification records, and more

Chat vs. Project: Two Conversation Modes

Codex offers two conversation modes suited for different scenarios:

Chat mode is similar to the web version of ChatGPT, ideal for lightweight tasks—explaining concepts, writing a piece of copy, editing a sentence, brainstorming a few headlines, etc.

Project mode is where Codex's core advantages shine. It manages conversations through folders, keeping all related files in one place for easy retrieval and modification. When creating a project, you have two options: "Start from scratch" to create an empty folder, or "Use existing folder" to import existing materials.

For content creation scenarios, for example, you can import client profiles, user personas, product information, scripts, and other files from your Obsidian knowledge base into a project. The Agent will read these background materials before providing analysis, rather than answering from scratch.

Multi-Threading and Task Management Tips

Parallel Execution of Multiple Tasks

Codex supports opening multiple conversation threads within the same project without interference. For example, you can simultaneously have the Agent research topics, write scripts, and design covers—three threads running in parallel.

The key rule is: Different threads within the same project share folder materials but do not share chat content. In plain terms, they can all see the same background materials but don't know what the others have discussed with you. You can also run threads across projects, in which case even folder materials are not shared.

You can determine task status through the left-side icons: a spinning circle means in progress, a blue dot means completed, and "Approve" text means it needs your confirmation.

Branching Feature

This is an extremely practical function. You can duplicate a new conversation path from any dialogue node, continue chatting with a different approach, while the original conversation remains fully intact.

Branching is particularly useful for solving context compression issues—when multiple rounds of conversation fill up the context window, the Agent may automatically compress content, leading to degraded performance. By branching, you can continue working in a new thread without repeatedly rebuilding context.

Completed tasks can be "archived," moving them to storage rather than deleting them. When needed, you can unarchive them in settings to restore them.

Core Features of the Codex Conversation Area

Planning Mode

With planning mode enabled, the Agent won't execute tasks directly. Instead, it first breaks down the task, creates a plan, discusses the approach with you, and only begins execution after confirmation. Strongly recommended for complex tasks—output quality improves significantly.

Permission Management

Permissions determine how much autonomy you give the Agent:

• Default mode: Works only within the current project folder; accessing the internet or operating on files outside the project requires your approval first
• Full access: The Agent can freely operate on computer files—convenient but higher risk
• Auto-review: A balanced option between the two

Default permissions are recommended for everyday use. When permission pop-ups appear, you can first ask the Agent about the purpose and risks of the requested permission.

Model and Reasoning Intensity Selection

The more complex the task, the higher the reasoning intensity should be. Low intensity is fine for simple copywriting, but full proposals, project modifications, and coding require stronger models and higher reasoning intensity. Among speed options, "Fast" consumes more quota, while "Standard" works for the vast majority of tasks.

Personal tip: When context usage is maxed out, start a new conversation whenever possible—AI output quality will be better.

Codex Memory System: Making the Agent Truly Understand You

Codex's memory feature operates on two levels:

Project Memory (Agent.md)

Create an agent.md document in the project folder's root directory—essentially an "onboarding manual" for the AI. The simplest way to create one is to have Codex read through the current project and auto-generate it, then manually review and optimize.

Global Memory

Configured in "Settings > Custom Instructions," this applies to all projects on your computer. If project memory is a "department handbook," global memory is the "company rules handbook."

Advanced technique: Set up an automated task to have the Agent review the past 24 hours of work daily and automatically optimize each project's agent.md document.

Codex Plugin Ecosystem: Extending Possibilities Infinitely

Codex's plugin system bundles external tools, MCP services, and Skill templates together—users just install and use. Some noteworthy plugins:

• Document plugins: Generate Word, PPT, and Excel files
• Browser control plugin: Lets the Agent operate a browser to scrape Bilibili creator data, product information, Twitter trending comments, etc.
• Chrome extension plugin: Runs in background tabs, supporting multi-page parallel tasks without occupying your browser
• Remotion plugin: Generates animated videos with impressive results
• Vercel plugin: One-click deployment of web pages to the cloud

Practical example: Have the Agent scrape AI industry hot topics from across the web daily, automatically generating content creation asset documents and spreadsheets, while also leveraging GPT's image generation capabilities for illustrations.

Skills: Solidifying Workflows into SOPs

Skills are the feature content creators should pay most attention to in Codex. They solidify repeatedly executed workflows into SOPs that AI can automatically execute.

Three Ways to Install Skills

1. Official Skills: Install directly from the skill marketplace; if unsure about the purpose, install first and then ask the Agent
2. Third-party Skills: Find highly-rated Skills on GitHub, send the URL to the Agent and let it install automatically
3. Custom Skills: Describe your requirements and invoke the Skill Creator to auto-generate

For example, converting video to illustrated text notes: Tell the Agent your requirements and screenshot rules, and it will invoke the Skill Creator to generate a complete Skill.md file. Afterward, you only need to provide the video path and script to automatically generate a well-illustrated, beautifully formatted article.

The storage path of a Skill determines its scope: placed in a project folder, it only applies to that project; placed in the global directory (the hidden .codex folder in the user directory), it applies to all projects.

Automation Tasks and AI Programming in Practice

Scheduled Automation

Set daily, weekly, or monthly repetitive work as scheduled tasks. For example, automatically scrape AI hot topics every morning at 8 AM and push notifications, or automatically review the week's content performance every Sunday and provide optimization recommendations. After creation, you can view and manage task status, execution times, and models used in the left-side automation panel.

AI Programming in Practice

Codex originally started from AI programming scenarios. For content creators, the most practical use cases include building personal websites, course marketing pages, or event registration pages. Combined with the Vercel plugin, you can deploy with one click, generating a public URL for others to access.

Computer Control

Codex can directly operate applications on your computer without occupying the current window—executing silently in the background. Users have already leveraged this feature with the HyperFarms plugin to have AI independently research websites, capture screenshots, and produce promotional videos.

Summary: How to Unlock Codex's Maximum Value

Codex's core value lies in this: It's not just a conversation tool—it's an AI Agent that can handle tasks for you from start to finish. From project management, multi-threading, and memory systems to the plugin ecosystem, Skill packages, and automated tasks, it builds a complete AI workflow system. For content creators, the keys to unlocking Codex's maximum value are solidifying high-frequency workflows into Skills, setting up automated tasks, and making full use of the plugin ecosystem.