Codex Desktop sent over 1 GB during a small HTML task; possible repeated upload of reference images/video

What version of the Codex App are you using?

The exact Codex Desktop version was not captured at the time of reproduction.

What subscription do you have?

ChatGPT Pro

What platform is your computer?

macOS, connected through an iPhone Personal Hotspot / tethering connection with a limited data allowance.

Which model were you using?

GPT-5.6 Sol Ultra

What issue are you seeing?

While using Codex Desktop to create and edit a single HTML file, approximately 15 GB of my mobile tethering allowance disappeared within a very short period.

I cannot conclusively attribute every byte of the 15 GB to Codex. However, macOS Activity Monitor showed a rapid and continuous increase in outbound traffic from the Codex process during the same task.

The screenshot attached to this issue is a capture of the macOS Activity Monitor Network tab.

The observed Codex network counters were as follows:

• Before starting the task, Codex showed approximately 50 MB of Sent Bytes.
• Shortly after the task started, Sent Bytes rapidly increased to approximately 450 MB.
• The outbound traffic continued increasing.
• When Codex reached approximately 1.3 GB of Sent Bytes, I manually stopped and terminated the task because the traffic was still increasing.
• Received Bytes remained comparatively low, at only a few MB.

This was a relatively small task involving the creation of one HTML file.

The HTML file itself did not contain any <img> or <video> tags. It was not downloading or serving image or video resources as part of the resulting webpage.

I had provided the agent with several reference images and one reference video only as design references. These assets were not intended to be embedded in the resulting HTML file.

Because the outbound traffic was extremely large compared with the size of the HTML file, and because received traffic remained very small, I suspect that the reference images and/or reference video may have been uploaded repeatedly during agent execution.

It is also possible that the same reference assets were resent when the main agent delegated work to sub-agents, or whenever the task context was reconstructed for another agent call.

I cannot confirm that repeated asset uploads are the cause. This should therefore be treated as a hypothesis rather than a confirmed diagnosis. However, it appears to be the most plausible explanation for the unusually high outbound traffic.

Steps to reproduce

1. Connect a Mac to the internet through an iPhone Personal Hotspot or another metered connection.
2. Open Codex Desktop.
3. Select GPT-5.6 Sol Ultra.
4. Open macOS Activity Monitor and select the Network tab.
5. Record the initial Sent Bytes and Received Bytes values for the Codex process.
6. Provide one or more reference images and a reference video to the agent.
7. Ask Codex to create or edit a single HTML file based on those references.
8. Allow the task to use sub-agents.
9. Monitor the Sent Bytes and Received Bytes values while the task runs.
10. Observe whether outbound traffic increases by hundreds of MB or more.

Actual behavior

• Codex initially showed approximately 50 MB of Sent Bytes.
• Shortly after starting the HTML task, Sent Bytes rapidly increased to approximately 450 MB.
• The counter continued increasing until it reached approximately 1.3 GB.
• I manually terminated the Codex task at approximately 1.3 GB because the outbound traffic was still increasing.
• Received traffic remained only a few MB.
• Approximately 15 GB of the iPhone tethering allowance disappeared during the overall HTML creation session.
• The resulting HTML file did not contain <img> or <video> tags.
• The only large media files involved were reference assets supplied to the agent.

Expected behavior

Creating a single HTML file should not generate gigabytes of outbound network traffic.

Reference images and videos should not be uploaded repeatedly unless this is strictly necessary and clearly communicated to the user.

If the same reference asset must be used by multiple agents, it should ideally be uploaded once and referenced through an internal asset identifier, hash, or cache instead of being transmitted again for every agent or request.

Why this is important

This behavior can consume an entire mobile data allowance within minutes.

In my case, approximately 15 GB of tethering data disappeared while creating a single HTML file.

Users on metered connections currently have no clear warning that providing reference images or videos may result in very large or repeated uploads.

Codex Desktop should provide at least one of the following:

• Reuse or cache previously uploaded reference assets.
• Avoid sending the same asset separately to every sub-agent.
• Display the estimated upload size before starting a task.
• Warn users when a task may generate unusually high network traffic.
• Provide a low-data or metered-connection mode.
• Show per-task upload and download statistics.
• Allow users to prevent reference assets from being forwarded to sub-agents.
• Stop or request confirmation when outbound traffic exceeds a configurable limit.

Additional information

The attached file is a screenshot of macOS Activity Monitor showing the Codex network activity.

The HTML itself did not include any images or videos, and the issue was not caused by media tags in the generated webpage.

The concern is specifically that reference images and the reference video supplied to the agent may have been transmitted repeatedly during agent execution or sub-agent delegation.

I stopped Codex manually when its Sent Bytes counter reached approximately 1.3 GB. The final amount may have been higher if the task had been allowed to continue.

If there is a way to enable verbose network logging or request tracing in Codex Desktop, I am willing to reproduce the problem and provide sanitized diagnostic information.

<img width="1152" height="1536" alt="Image" src="https://github.com/user-attachments/assets/32232c43-47e7-4086-a15b-c1c942fd284d" />