Desktop app transcript scroll jumps during streaming and moves current response offscreen

Summary

The ChatGPT/Codex desktop conversation view repeatedly loses its scroll anchor while an assistant response is streaming or finalizing. The transcript jumps up and down, and the current response is frequently moved completely offscreen.

This began recently and reproduces on two separate Mac computers, making a machine-specific cache or hardware issue unlikely.

Environment

• ChatGPT/Codex desktop app
• macOS, Apple silicon
• Confirmed affected build on one computer: 26.803.41515
• A second Mac is also affected; its exact build has not yet been confirmed
• Began in early August 2026

Steps to reproduce

1. Open a conversation in the desktop app.
2. Send a prompt that produces a streaming response.
3. Watch the transcript while the response streams and transitions to its final state.
4. The viewport shifts repeatedly up and down. In many turns, the current response scrolls completely offscreen.

This occurs during normal conversation use and happens on most responses. The correlation with Local, Remote, or Cloud thread targets has not yet been established.

Expected behavior

The transcript should either remain anchored to the current streaming response or preserve the user's chosen scroll position without unexpected movement.

Actual behavior

The scroll position changes without user input as transcript content renders or changes state. The viewport may jump in both directions and leave the newly completed response outside the visible area.

Additional context

The behavior appearing at approximately the same time on two computers suggests either a desktop-app regression or an account/server-side rollout affecting transcript rendering or scroll anchoring.