[macOS] PDF file preview completely blank on 26.901.51231; recovered after update

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

Versions read from the installed application metadata during troubleshooting.

• Affected installed version: Codex 26.901.51231, build 8109.
• Version after recovery: Codex 26.908.70816, build 9275.

What subscription do you have?

Not included.

What platform is your computer?

macOS 15.3.1 (24D70), Apple Silicon arm64.

What issue are you seeing?

Codex's PDF preview displayed a completely blank panel on macOS. The failure affected a PDF from a remote task and a minimal PDF stored directly on the Mac. There was no visible page count, loading message, or error. The user confirmed that PDF preview worked again after updating Codex.

Observed and investigated on September 16, 2026.

What steps can reproduce the bug?

1. Open a PDF through Codex's file-preview UI. The original failure involved a remote task.
2. To remove remote transfer as a necessary condition, open a directly linked local PDF: a one-page, 603-byte ASCII test file named pdf-preview-probe.pdf.
3. The user confirmed that this local file also produced a completely blank preview panel, with no page indicator, loading text, or error message.

Actual: the preview area remained entirely blank.

These steps describe what was observed in the affected application session. The issue has not been reproduced since the update.

What is the expected behavior?

Display the PDF page, or provide a visible actionable error if loading fails.

Additional information

• The same local test PDF rendered correctly in macOS Quick Look, PDFium, and MuPDF. The first page of the original PDF also rendered correctly in all three.
• The app's deep code-signature verification passed. Inspected preview resources matched the packaged integrity metadata, and the bundled PDF.js API and worker versions matched (5.4.296).
• Updating to 26.908.70816 (9275) restored PDF preview, as confirmed by the user.
• No proxy, global environment, font configuration, or application package changes were made during troubleshooting.

The update may also have restarted the app. This evidence does not isolate a specific code change, prove that the new version contains a targeted fix, or establish the underlying runtime cause.

Please investigate why the file-preview panel could remain completely blank without surfacing a loading state or error, including whether a stalled file-loading or renderer state can cause this behavior. Better diagnostics would have made this incident much easier to identify and resolve.

Related: #45662. That report describes page placeholders in a newer macOS version of the app; this report concerns an earlier version and an entirely blank panel with no page indicator. They may share a cause, but that has not been established.

The minimal test PDF contains only synthetic ASCII content. Private source documents, internal infrastructure details, full conversation history, and raw logs are intentionally excluded from this report.

Start by testing the named one-page pdf-preview-probe.pdf through the file-preview UI on the affected and recovered app versions, comparing the blank state with the expected page or an actionable error. Investigate the loading and rendering path, using the reported PDF.js API and worker version information as context; done means a failed load no longer remains silently blank and a reproducible cause or diagnostic is identified.