Choosing a Codex platform

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What you will be able to do

Separate the interface from execution

An interface is where you send a request; the environment is where the agent works. Desktop, CLI and IDE can operate on local projects, while remote projects and cloud tasks involve another environment. A phone's small screen does not make its task smaller, and similar desktop windows do not establish that the same computer is working. Map request origin, executing machine and result location before comparing buttons.

Step 1: start from your existing workflow

If you prefer a graphical workspace and managing several tasks, start with desktop setup. Use the official Windows or macOS procedure for your platform. On Linux, choose the desktop preview package for a supported distribution and architecture; a Windows installer is not interchangeable. Linux desktop availability does not establish identical Remote host support: verify those features separately.

Choose CLI if you already navigate folders and run tests in a terminal, or intend to connect work to scripts. Native Windows and WSL are different environments with separate installations, home directories and paths. User paths are not interchangeable between macOS and Linux either. If terminals are unfamiliar, begin with terminal paths rather than learning two shells at once.

If you already code in an officially supported editor and want to include an open file or selection, use the IDE extension. Confirm official availability for your editor rather than installing an item merely because its marketplace name looks similar. Even with both desktop and IDE installed, use one interface for the first edit; concurrent tasks editing the same file make attribution difficult.

Step 2: decide whether cloud or mobile is needed

Use cloud tasks when you want a configured remote environment to work on a GitHub repository and return a diff or PR for review. Record repository and branch first. Uncommitted local changes do not appear in cloud just because the project name matches. Supply the correct version to the environment rather than repeating an ambiguous request. Without a practice GitHub repository, the local route still supports the introductory lessons.

Consider mobile Remote to follow or continue computer work while away. Documentation describes iOS and Android controlling available macOS or Windows desktop hosts, with host connectivity, pairing and workspace permission required. This does not move npm, the project and its local browser into phone storage. If the host is off or offline, restore its availability rather than installing packages in a phone terminal to fix the connection.

Step 3: verify with one small task

Create an empty codex-platform-check folder and put the single line Practice marker: local-copy-A in a plain-text file named location.txt. Open that folder in desktop or IDE, or enter it before starting CLI. For cloud, create and commit the same file in your practice repository and select a branch containing it. Do not upload a production project merely to test an interface.

Read location.txt without changing files.
Report the exact marker, working directory, and where commands for this task run.
Distinguish verified facts from anything you cannot determine.
Do not install tools, create files, or change settings.

Expect local-copy-A and a working path supported by tool results. Some interfaces use isolated working copies, so the path need not literally match your desktop path; the selected branch, marker and environment should agree. If the host identity cannot be established, record it as unknown and inspect connection settings rather than accepting a guess.

Boundary exercise: change the local marker to local-copy-B without committing it. An existing cloud copy may still read A, demonstrating different file versions rather than a model forgetting. A phone controlling the same host and folder should observe that host's current file. Reporting the source and marker is more useful than simply asking whether something is latest.

How to finish with only one computer

If cloud or Remote is not configured, complete the read check through your chosen local interface; no new account connection is needed for this lesson. To compare copies, create two separate sibling folders, copy-a and copy-b, with location.txt in each. Change only copy-b's marker to local-copy-B, then open each folder and run the read-only prompt above. Expect local-copy-A from A and local-copy-B from B; inspect the working directory before the marker. This demonstrates two distinct local files, not successful cloud synchronization or a phone connection.

Troubleshooting and completion criteria

Missing interface: check official support, app version, account workspace and rollout status; keep an unavailable option unverified. Missing file: inspect folder, cloud branch or host, then commit state. Missing command: inspect tools where commands actually run; Node.js on your laptop does not prove it exists in cloud. These are interface, file-version and execution-environment issues, not all sign-in problems.

Restore marker A when finished and keep the practice folder for later; stop only the task created for this exercise. Complete this sentence: “I use interface __, files live in environment __, and I verify results with __.” If a new interface leaves the file location unclear, finish this read-only check before multitasking. Diagram numbers 1, 2 and 3 represent selecting an interface, identifying the environment and checking results.

Platform support was checked on 2026-09-14 against desktop, Linux preview, IDE, cloud and Remote documentation. This is documentation verification and an original exercise, not a claim of testing every device. Continue with terminal basics, your first project or cross-device work.

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Three numbered stages: identify the starting point, perform the exercise, and verify the result. Original illustration, not a product screenshot.

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