[Codex Desktop][Windows] Split pane oscillates continuously near a resize breakpoint after switching to a thread with image preview

What version of the Codex App are you using (From "About Codex" dialog)?

Codex Desktop package version 26.727.6591.0 (Windows Store package OpenAI.Codex).

Bundled Codex command runner observed: 0.146.0-alpha.9.2.

What subscription do you have?

Not included in this public report.

What platform is your computer?

• Windows x64
• OS build: 26200.8875
• Display scaling: 100% (AppliedDPI = 96)

What issue are you seeing?

After switching to a specific local project/thread that shows a long conversation in the center pane and an image/file preview in the right pane, dragging the divider between the center pane and the right preview pane causes the layout to oscillate continuously when the divider reaches a specific width range.

The divider and pane contents repeatedly move back and forth instead of settling at the pointer position. The behavior appears to be a responsive-layout breakpoint loop (for example, the layout may be repeatedly toggling between two minimum-width/collapse states).

The issue is thread/project-view specific: switching to the affected project/thread makes it reproducible. The affected thread was created in July and contains a generated image preview on the right.

A local desktop-log check did not find a resize/layout exception at the time of reproduction, suggesting this is a renderer/layout loop rather than a process crash.

What steps can reproduce the bug?

1. Open Codex Desktop on Windows.
2. Open a local project with a long existing thread that has an image or file preview displayed in the right-side pane.
3. Switch away to another project/thread.
4. Switch back to the affected project/thread so the conversation pane and right-side preview pane are both visible.
5. Drag the divider between the conversation pane and the preview pane horizontally.
6. Move the divider slowly through the narrow width range where the responsive layout changes.
7. Observe that the divider and panes begin rapidly oscillating/shaking and do not settle.

The issue reproduces again whenever the affected project/thread view is opened and the divider enters that width range.

What is the expected behavior?

The divider should follow the pointer smoothly, and the panes should remain stable at the selected width. If a minimum width or collapse threshold is reached, the layout should transition once and remain in that state.

Additional information

This appears related, but not identical, to:

• #20966 — Codex App file-content side panel jittering
• #20850 — Codex App flickers continuously when switching between sessions

Those reports are on macOS/older builds. This report is for Windows and specifically involves manually resizing the center/right split pane near a width breakpoint after switching to an affected thread.

A screenshot exists but was not attached publicly because it contains personal project and task names. A redacted screenshot or short screen recording can be provided if maintainers need it.