How to Use Codex in Cursor

Why Run Codex Inside Cursor at All

Cursor already puts editing, search, source control, and a terminal in one workspace. Adding Codex gives you a second way to delegate a bounded repository task while you inspect the files it changes. The useful benefit is context: you can point to a route, component, error, or test and review the result inside the project.

Use the Codex IDE extension for an editor-side conversation. Choose Codex CLI when commands and logs are the center of the task.

For the native extension path, see the Codex workflow in VS Code. If you prefer a terminal-led editor setup, compare the Windsurf workflow.

Install Codex and Open the Sidebar

1. Open Cursor and confirm the repository root is the active workspace.
2. Install the official OpenAI extension.
3. Sign in, then select Codex: Open Codex Sidebar from the command palette.
4. Ask for a project explanation with zero edits.
5. Request one small change and inspect the resulting diff.

Try: "Explain the signup flow. Name the files involved and make zero file edits."

Expected success: the Codex sidebar opens, the signed-in state is visible, and the first response names repository files without changing them. If the command is missing, confirm that the extension is enabled for the current profile, reload Cursor, and reopen the project.

Give Cursor a Reviewable Codex Task

Prefer the supported sign-in flow. Keep project secrets outside source files, screenshots, and prompts. Scope the task to named files or one behavior.

A good first edit prompt is: "Update the empty state in src/routes/projects. Change the user-facing copy in that section, return the changed files, and skip deployment commands."

For a checkable result, use: "Fix the failing profile-form test. Return: changed files, test command, test result, and any skipped check."

What to Do When Codex Won't Connect

Check the extension state, authentication, workspace, and network in that order. Reload Cursor, verify that the repository is trusted, and retry sign-in. If the extension still fails, run Codex CLI in the same workspace to separate an editor issue from an account or repository issue.

Keep secrets out of chat. Revoke any credential that was exposed and create a replacement.

When to Plan the App Before Opening Cursor

If the app is still at the idea stage, opening a repository may introduce technical decisions too early. HappySeeds gives non-technical builders a planning-first path for defining screens, actions, and acceptance criteria before choosing whether code is necessary.

Use an app template to structure the first version, then return to Cursor for the parts that require repository control.

Tested setup: HappySeeds Editorial Team; last reviewed July 30, 2026; Cursor 3.13.10 on macOS 14.8.7; official extension openai.chatgpt 26.721.30844 installed.

Choose the Right Starting Surface

If you are still deciding between a coding workspace and a guided app platform, compare Codex with an AI app builder before setting up the editor.