Codex / Getting Started

Codex quick start

Start Codex with a minimal closed loop: install, log in, open project, describe task, review diff, run verification.

quick start

The goal of a quick start is to create a minimal closed loop: install or open Codex, go into a low-risk repository, give it a clear task, allow it to be modified in small steps, run validation, and then review the results.

Do not directly refactor extensively when using it for the first time. First let Codex explain the project structure, dependencies, running commands and test methods to make sure it understands the context.

cd your-project
codex "First explain how this repository runs, do not change the files"

The first engineering task

Codex responds more stably to structured tasks. Write objectives, scope, limitations, acceptance criteria, and verification commands.

Goal: Fix the theme switching of the settings page not taking effect.
Scope: settings page and theme provider.
Restrictions: Do not change login, payment, database.
Acceptance: pnpm build passed; it will remain after the theme is refreshed.
Verification: Run pnpm build and note the changed files.

Review and continue

After the Codex is over, don’t just read the summary. View changed files, diffs, command output, and remaining risks. When you need to continue, let it make small adjustments based on the current diff.

git diff
pnpm build
pnpm test

Complete usage points

Supplement the core concepts, operation sequences, permission boundaries and verification requirements that are easily compressed and missed in official documents, making it easier for English readers to learn completely by page.

Complete entry closed loop

The quick start should cover five things: selecting the entrance, preparing the repository, writing tasks, approving the execution, and verifying the closing. The official documentation puts Codex in the development workflow instead of just giving a one-time prompt. The most common things that novices miss are "verification" and "review".

Select a low-risk repository or new branch and first confirm that there are no unsaved critical changes.
Let Codex explain the project structure, running commands, test commands and main risks. Don't let it edit it right away.
Write the first task as a project card, including goals, scope, prohibited items, acceptance criteria, and verification commands.
If the Codex requests higher permissions, first look at the command it wants to run, the path touched and the reason.
Review the diff, command output, and remaining risk when complete; ask it to make only small corrections if necessary.

The qualified result of Quick Start is not "the page looks changed", but that you can clearly explain which files were changed by Codex, why they were changed, what commands were used to verify them, and what other matters require manual judgment.

Study Checklist

Put the content on this page into real tasks and use the five dimensions of entry, context, permissions, verification and team rules to check whether you have truly mastered it.

Study Checklist

After reading this page, do not just remember the concept name. You should be able to place "Codex quick start" back into a real Codex engineering workflow: where the task starts, what context the system loads, which actions need approval, how the result is verified, and how to roll back when it fails.

If this is a concept page, be specific about how it affects the real task: does it change context, permissions, execution paths, validation methods, or changes the team collaboration process.

Be able to describe in your own words the specific problem this page solves, rather than just reciting the title.
Able to write a minimal example task with goals, scope, prohibitions, and acceptance criteria.
Be able to determine which information should be put into the current prompt and which should be captured as project rules or configurations.
Be able to explain which long-term rules should go into AGENTS.md, and which runtime behavior should be handled by config.toml, permission profile, skills and MCP.
Ability to check diffs, command output, test results, screenshots or PR notes after a task is completed instead of just trusting the natural language summary.

If this page is used for team training, ask learners to complete a small task with Codex: read and explain first, submit a plan, make the smallest useful change, and close with real verification commands plus human diff review.

Codex practical notes

Fill in the most overlooked execution details of Codex usage around local environments, privilege escalation, remote entry, automation failures, and rollbacks.

Codex Practical Notes

This page belongs to the core concepts of Codex. When learning, connect concepts to real-world implementation: will it change context, permissions, task splitting, verification paths, or change the way teams collaborate.

When handling tasks related to "Codex quick start", always confirm the current Git status and working directory first. Codex can make changes quickly, but it does not automatically know which uncommitted edits came from the user, which files are off limits, or which commands may affect production.

Prioritize using low-risk branches or working trees for local tasks, and review them with git diff after completion.
When it comes to installation dependencies, networking, databases, deployment, push, deletion, and reset, Codex must first be asked to explain the impact before approval.
Results generated by remote or collaborative portals must also be confirmed back to PR, CI, build logs and test evidence.
Automated tasks must define failure output and exit conditions in advance to avoid Codex repeatedly trying in the wrong direction.

Think of Codex as an engineering teammate who can execute commands, rather than an assistant who can only write text. The closer you get to a real system, the greater the need for clear boundaries, evidence, and rollbacks.