GitHub Copilot stopping GPT and resubmitting prompt shows ongoing mid-response output from previous submission.

[garretwilson]

1. Submit a complex prompt that requires reasoning and substantial output using GPT-5.5.
2. After submitting the prompt, as soon as the output starts being generated but before it is finished, hit the "stop" button.
3. Edit the prompt (even just changing punctuation from . to ? for example) and resubmit it.

Expected: The response will be generated from the beginning.

Actual: Often response will be an ongoing continuation of the previous output that was cancelled, even starting mid-sentence.

This may happen several times, with the user canceling the response and resubmitting the prompt; each time, the output is a mid-response continuation of the previous submission.

I've seen this many times with GPT-5.5. I've never seen it with Opus 4.7.

Version: 1.121.0 (user setup)
Commit: f6cfa2ea2403534de03f069bdf160d06451ed282
Date: 2026-05-19T11:51:53+02:00
Electron: 39.8.8
ElectronBuildId: 13870025
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.26200

[justschen]

cc @connor4312 this is maybe related to the timeline service? seems like the request is not cleared on restoring