Remote setup, diagnosis and disconnection

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Goal: identify the environment your phone controls

Remote lets a phone send prompts, approvals and follow-ups while the host supplies files, tools and signed-in services. It does not turn the phone into a desktop-tool runtime or establish a Codex cloud upload. Review the mobile overview. iOS and Android are alternatives; you do not need both. This route connects one existing computer without renting a server.

In the workflow illustration, 1 identifies the host and directory, 2 sends a fresh read-only request, and 3 checks the result against file contents. Follow that order. A host appearing in a list satisfies only part of step 1, not steps 2 and 3.

Before setup: both devices and the work location

Use a supported ChatGPT desktop host with Codex access in the same account/workspace, awake, online and running the app. Update the official ChatGPT mobile app. Complete required SSO, MFA or passkey steps; an administrator may also need to enable Remote Control. Availability rolls out in stages. Missing Remote controls call for version, workspace and access checks first.

The documented mobile Remote hosts are macOS and Windows; a Linux desktop preview does not establish support for this pairing route. Initial setup starts from the desktop app, not CLI or IDE sign-in. The phone does not supply missing Git, Node.js, browsers, Skills or MCP configuration. Check required tools on the machine that will actually execute the task.

Step 1: prepare an identifiable host project

Create a new codex-remote-lab folder on the host and save two plain-text files. Put the first block in host-marker.txt and the second in request.txt. REMOTE-LAB-A is a fictional exercise marker, not the actual host name. Separately record the device name shown in the app and the real project path. Use a new folder name if it exists.

REMOTE-LAB-A
Revision: 1

Read the host marker and report it. Keep both files unchanged.

Add that folder as a desktop project and create a read-only practice task that reports its path and two files. Confirm host-side access first. Use Get-Location/Get-Content in the Windows practice folder or pwd/cat on macOS. Establish this local baseline before Remote, so missing files are not mistaken for connection failures.

Step 2: enable access and pair the phone

On the intended host, open Settings → Connections → Control this Mac or PC, choose Set up or Add and complete access/verification prompts. Setting up a different empty computer on the same account will not automatically provide this host's folder. The QR code pairs a device with the host; keep it out of public teaching material and do not send it to others to scan.

Scan with your iPhone or Android, confirm the official ChatGPT app opens, and complete Remote setup with the same account/workspace. Success should show the host in the phone's Remote list. Each phone-host pair needs pairing; signing in on both is not sufficient evidence. If the link stays in a browser, check the updated app and opening route first.

Review connection and keep-awake settings on the host. For a Mac laptop, connect power and keep the lid open; selecting Sleep still stops availability. Windows Computer Use tasks need an unlocked, available session. This file-reading exercise does not require enabling every browser or desktop-control capability. Arrange a suitable work period if someone else uses the host.

Step 3: verify three pieces of evidence

In phone Remote, select this host, the codex-remote-lab project and the existing task, then send the prompt below. An ordinary phone chat without a host association does not establish file access. Recheck the execution location if creating a new task. Matching task names do not establish matching environments.

In this host project, read host-marker.txt and request.txt without changing files. Report the host/environment name if available, the actual working directory, and both files' exact contents. Do not infer unavailable information or use other services. If either file is missing, stop and report that.

Expect the real directory, REMOTE-LAB-A with Revision: 1 and the original request.txt text. If host identity is unavailable, the response should say so rather than treat the marker as the actual device name. Independently compare both files on the computer and inspect the read record. Host selection, working path and file contents are separate checks; keep any missing check unresolved.

Test freshness after the task finishes: edit only the marker's second line on the host to Revision: 2 and save. From the phone, request a fresh file read rather than a summary. Expect Revision: 2. An old 1 calls for checks of stale replies, unsaved edits or a different folder. Restore 1 on the host and reread so the exercise is repeatable.

Disconnection and stopping remote access

After current work completes, temporarily disable the host's allow-connections control, check access from the phone, then re-enable it on the host and verify reconnection. This can affect all paired devices, so first confirm no other remote work is in progress. Treat connection availability, pairing removal and task cancellation as separate states rather than assuming one control performs all three.

Official documentation states that sign-out turns off Remote Control but retains pairings; re-enabling may be needed after sign-in. Do not treat logout as permanent device revocation. For an individual pairing, inspect the host's current Connections device list and available management actions, then verify loss of control from the original device. The documentation does not establish one removal-button label across all versions.

Record connection, pairing and task state separately

Worked case: after Remote Control is turned off, the phone cannot control the host, but the host still shows a running task. You have established disabled remote access, not cancellation or removal of a device pairing. To stop the task, separately use its stop control and inspect the result. To remove a device, separately inspect Connections management and whether the original device retains control. If your version offers no clear removal action, record removal as unverified rather than treating sign-out as permanent revocation.

Checked at: [time and timezone]
Controller and execution host: [your private labels]
Remote Control: [on / off / unknown]
Device pairing: [present / removed / unknown]
Task execution: [running / stopped / completed / unknown]
Last fresh file read: [time, path and revision / not verified]
Action taken: [exact control used / none]
Next verification: [what remains to check]

Completion and further reading

Success means identifying the host, freshly reading the correct path, recognizing the updated marker and knowing how to stop remote access, not merely receiving a notification. Review tool activity and results in the task. Continue with iPhone, Android and cross-device handoff. For independent execution while your computer is off, learn the separate cloud-task environment and delivery workflow.

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Read the full description

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

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