Codex Code Review in the ChatGPT Desktop App: Setup and Use

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Codex Code Review is the new code review experience in the ChatGPT desktop app, announced at DevDay on 29 September 2026 and available on all plans. It puts a pull request's description, changed files, comments, and checks in one place, lets you ask Codex about potential issues, and sends your feedback to GitHub pull requests or GitLab merge requests. The Code Review docs describe each screen, and this guide walks through setup, one full review pass, and automatic reviews.

Codex Code Review availability and usage

Code Review usage applies only when Codex runs reviews through GitHub, such as an @codex review comment or an automatic review. Reviews you run locally or outside GitHub count toward your general usage limits instead.

Set up Code Review in the desktop app

The desktop app includes Code Review, and you can pin it to the sidebar from your installed plugins.

1. Open Code Review from the sidebar.
2. Connect your source account when prompted, using an account that can access the repository.
3. Select a pull request from the sidebar, or paste its link into the search field.
4. Read Summary for the description, activity, comments, and checks. Open Changes to see the diff with comments beside it.

Your personal inbox collects GitHub pull requests across repositories under Assigned to me, Assigned to my team, and Authored by me. Select the pin in a review's toolbar to keep it under Pinned. In Changes, Mark as viewed tracks the files you have read for the displayed revision. When a change spans dependent pull requests, Stack in Summary opens the related ones.

Review a pull request with Codex

Select Review with Codex to start a review in a new chat. State the behavior you expect before you ask what is wrong, because Codex can only check a change against an expectation it knows. Here is a prompt for a change to an API rate limiter:

Walk me through this pull request. Each API key should still get 100 requests per minute, and requests over the limit must return 429 with a Retry-After header. Show me the code path and the tests for the over-limit case, and tell me what is not covered.

Select a finding to see its explanation and the relevant lines in Changes. Check it against the latest diff, the expected behavior, and the tests before you call it a bug. You can stop a running review from the review chat.

For criteria that apply to every review, select the Review instructions gear next to Review with Codex, or open Settings > Code Review. These instructions apply across repositories to reviews you start with Review with Codex:

Start with a two-line summary. Prioritize behavior changes, data loss, missing authorization checks, and missing edge-case tests. For each finding, give the triggering input, the expected behavior, and the actual behavior. Skip style comments, because CI handles formatting.

Keep questions about one change in that pull request's chat instead. The Comic book, Visualization, and PDF options add a suggested instruction for explaining the change in that format.

Post feedback without surprises

Reviewing a pull request in chat does not post comments, approve, or merge. You decide which findings to share. Ask Codex to draft a comment as a draft, then check its file and line references yourself.

Watch one behavior closely. Posting a comment in Summary or Changes sends it to GitHub or GitLab immediately, without waiting for Submit review. Keep drafts in the chat until you are ready, then use Submit review to choose Comment, Approve, or Request changes.

If you wrote the pull request, return to it and ask Codex to address specific feedback, then inspect the changes and run the tests. In Codex, Fix in Checks attaches failing checks to the chat without sending anything, so you can add your own prompt first. Code Review cannot edit pull request descriptions that contain images, so open GitHub for those.

Turn on Codex automatic code review

Automatic cloud reviews let Codex take a first pass on GitHub pull requests while you are away. Comments appear on GitHub and in Code Review, and you do not need to create or manage a cloud environment.

1. Connect the GitHub repository to Codex. You need push or admin permission on the repository.
2. Go to Codex settings, choose the repository, and turn on Automatic review under Review code.
3. Under Personal preferences, turn on Automatic review and pick when reviews run with Review trigger.
4. Open a small test pull request and wait for the Codex review.

On GitHub, Codex flags only P0 and P1 issues, so its comments stay on high-priority risks. You can also ask for a review in a pull request comment:

@codex review
@codex review for issues in the database migration
@codex fix the P1 issue

The fix request starts a legacy cloud chat with the pull request as context, and Codex can push a fix to the branch when it has permission.

To teach Codex your repository's rules, add a Code Review Rules section to the AGENTS.md file closest to the code it governs:

## Code Review Rules

- Handlers under api/ must check the caller's organization before reading records. Safe path: use the shared tenant guard.
- Migrations must stay compatible with the previous release. Flag dropped or renamed columns.

The GitHub guide suggests starting with two or three rules, keeping lint and formatting in CI, and narrowing rules that produce noise. Rules guide Codex, but they do not replace tests, branch protections, or required approvals.

Review local changes before you push

For work that is not a pull request yet, type /review in the CLI, the IDE extension, or the app composer. The CLI presets review against a base branch, uncommitted changes, a single commit, or custom instructions, and none of them change your working tree. For scripts, the CLI reference documents codex review --base main and codex review --commit SHA. Set review_model in config.toml if reviews should use a different model from your session.

A sensible order is local /review before you push, automatic review when the pull request opens, then your own pass in the desktop app. Our Delegate, Review, Own methodology covers the last step: Codex takes the first pass, and you own the decision.

Turn on automatic review for one repository today and compare its first three findings with your own review.

Further reading

• Code Review in the ChatGPT desktop app
• Review GitHub pull requests with Codex
• Review GitLab merge requests with Codex