DOCX preview auto-fit zoom continuously oscillates between 61% and 63%
What version of the Codex App are you using (From “About Codex” dialog)?
26.721.81911 (build 5973)
What subscription do you have?
ChatGPT Pro
What platform is your computer?
Darwin 25.5.0 arm64 arm (macOS 26.5.2, build 25F84; Apple Silicon)
What issue are you seeing?
When a DOCX file is open in the Codex App's built-in document preview, the automatic-fit zoom value continuously alternates between 61% and 63% while the app is idle. The preview visibly flickers/repaints on every change.
The window geometry, sidebar width, document content, page breaks, line wrapping, and margins remain unchanged while the two zoom values alternate. The DOCX otherwise renders correctly.
The source document is an unpublished manuscript containing PII, so the raw screenshots are intentionally not attached to this public issue.
What steps can reproduce the bug?
- Open a DOCX file in the Codex App so that it appears in the built-in document preview.
- Leave the preview at its automatically calculated fit zoom.
- Keep the app window and sidebar dimensions unchanged and do not interact with the preview.
- Observe the zoom indicator repeatedly switch between 61% and 63%, with the page preview flickering each time.
Observed with the app UI in Simplified Chinese (zh-CN).
What is the expected behavior?
The automatic-fit zoom should settle on one stable value while the viewport and document are unchanged. It should be recalculated only after an actual size or layout change, and the idle preview should not flicker.
Additional information
The stable document layout together with the exact two-value oscillation suggests a possible feedback loop in the auto-fit measurement or rounding logic—for example, one computed zoom slightly changing a measured preview width and causing the next calculation to choose the other zoom.
Searches for existing issues using DOCX zoom preview, document preview flicker, and auto-fit zoom did not find a matching report as of 2026-07-30.