Unexpected Usage Draining

What version of the IDE extension are you using?

26.415.20818

What subscription do you have?

Plus

Which IDE are you using?

VS Code

What platform is your computer?

Linux 6.17.0-20-generic x86_64 x86_64

What issue are you seeing?

In the VS Code Codex extension, usage continues a high draining unexpectedly after a very small task has already finished. I reproduced this with GPT-5.4 Mini on low reasoning by sending only a simple “Hello World” prompt. The response completed normally, but the usage meter kept increasing for several minutes afterward, as if a hidden background task or session was still consuming credits. No visible active thread or running process was shown in the IDE.

The "Hello World!" was sent at 11:59 local time.
<img width="613" height="204" alt="Image" src="https://github.com/user-attachments/assets/cb02aa69-115e-4f89-9fec-89c0bf0b1956" />

Local rollout logs indicate that the original “Hello World” session completed normally, but additional rollout sessions were created immediately afterward. Those later sessions appears to be unrelated to the original prompt and shows substantially higher token usage, which is consistent with the unexpected usage drain I observed in the VS Code Codex extension. This is especially concerning because the IDE did not clearly show an active follow-up task while usage continued to increase.

<img width="918" height="74" alt="Image" src="https://github.com/user-attachments/assets/51c2a1b5-a7f9-4dc7-8824-574f33dc881c" />

42377 Apr 17 11:59 rollout-2026-04-17T11-59-20-019d9bf4-1ede-74f0-817b-d2bc4359957a.jsonl
214806 Apr 17 12:00 rollout-2026-04-17T12-00-06-019d9bf4-d364-77f1-9166-3316042337b0.jsonl
167900 Apr 17 12:02 rollout-2026-04-17T12-02-56-019d9bf7-69d0-7da1-b40e-3d636e6977b6.jsonl

What steps can reproduce the bug?

1. Open VS Code and check the Codex usage meter.
2. Start a new chat/thread in the Codex extension.
3. Select GPT-5.4 Mini with low reasoning.
4. Send a minimal prompt such as “Hello World”.
5. Wait for the response to complete.
6. Observe that the usage meter continues increasing for some time even though the task has already ended and no active process is visible.

What is the expected behavior?

A trivial prompt should consume only a very small amount of usage, and usage should stop increasing once the task is finished. If anything is still running in the background, the IDE should clearly indicate it.

Additional information

I recorded a video showing the issue and will attach it to this report. The test was intentionally minimal to isolate the problem. I only reproduced this in the VS Code Codex extension so far, so at the moment it appears to be IDE-related.

Video: https://www.youtube.com/watch?v=ZBR5zBVM5Jw