Learn by doing
Walkthroughs
Short, step-by-step setup guides. Each one ends with a working result and links its official sources.
Learn by doing
Short, step-by-step setup guides. Each one ends with a working result and links its official sources.
Attach the folder that holds your work to a Codex project, so Codex reads the right files and saves changes where you expect.
A Codex project attached to This Project, with a first chat that confirms Codex can find the intended files.
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Members onlyCopy the directions into Codex. Your agent can help with the setup; the steps below explain what to do and what to check.
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Your work might live in a folder of meeting notes, research, a website, or documents you are writing. Once that folder is attached, Codex can compare your notes or revise a document where it sits, without you copying files into a chat.
A Codex project groups related chats and attached folders. Choose the folder for this work, then ask Codex to list its files before requesting edits.
A folder that holds the material for one piece of work lets Codex find what it needs. For a workshop, that could be the outline, notes, and exercises. A parent folder full of other projects leaves Codex to sort out which files belong.
Find the folder on your computer, or make one and move this work's files into it. If you need help choosing, ask Codex which files the work needs once you open it in the next step.
Check: The folder's name and contents match the work you have in mind.
This walkthrough calls the folder This Project. Use the actual name of the folder for your work.
A project keeps related chats and their folders together, so you can return to this work later. A local project works with folders on your computer.
In the ChatGPT desktop app, choose Codex from the ChatGPT dropdown. Create or select this work's project, then choose Edit project from its menu to see the attached folders.
Check: You are viewing the folder list for the project you intend to use.
If a control is unavailable, describe what you see to Codex and ask it to check OpenAI's Projects and chats page.
Codex can read and change files in every attached folder, so attach This Project and not a broader folder around it. Codex reads project instructions only from the primary folder.
Choose Add folder if your folder is missing, then select it on your computer. If the project has several folders, hold the pointer over yours and choose Make primary.
Check: The project's primary folder is the one you chose.
If several folders have similar names, open each one and check its contents before you attach it.
Before Codex edits anything, confirm it is looking in the right place. A file list is a quick check that changes nothing, and you can compare it with the folder on your computer.
Start a new chat in the project and choose Local. Ask: “List the files directly inside this project’s primary folder without changing them.”
Check: The file names Codex lists match what you see in the folder.
Local works directly in your folder. Worktree works in a separate copy of your folder on your computer, and Cloud runs on OpenAI's computers. This walkthrough uses Local.
Understanding
Codex needs to know which folder holds this work. New chats in a project start in its primary folder, where Codex reads instruction files such as AGENTS.md, a plain text file where you or Codex write how this work should be done, such as the tone to use or files to leave alone. The folder sets where Codex looks; the permissions control below the message box sets what it may change. Tell Codex what you want changed, then check its proposed or finished changes against that request.
Open the project's menu, choose Edit project, and check the attached folders. Use Add folder to attach the intended folder, then confirm which folder is primary.
Go back to the Projects list in the sidebar and start the chat from This Project, or select that project in the message box.
Replace the broad folder with the specific project folder. Then check the permissions control below the message box; the default, Ask for approval, lets Codex edit inside the project's folders and asks before it changes files outside them or uses the internet.
The dates below show when each official source was checked against the steps on this page.