Codex Desktop: PDF annotation toolbar appears from assistant file link but not file sidebar

What version of the Codex App are you using?

Not captured. This was observed in Codex Desktop on macOS.

What subscription do you have?

Not relevant / not captured.

What platform is your computer?

macOS.

What issue are you seeing?

When opening the same local PDF in Codex Desktop, the available tools differ depending on the entry point:

• Opening the PDF from a Markdown/local file link in an assistant response shows an annotation/comment option.
• Opening the same PDF from the file window/sidebar opens a preview without the annotation option.

This makes the annotation affordance feel inconsistent and hard to discover. From a user perspective, the same PDF in the same workspace should either expose the same annotation tools or make clear why one viewer is read-only.

Steps to reproduce

1. In Codex Desktop on macOS, work in a local workspace containing a PDF.
2. Have the assistant emit a Markdown link to the local PDF, for example [example.pdf](/path/to/example.pdf).
3. Click the assistant-authored link and observe that the PDF opens with an annotation/comment option.
4. Open the same PDF from the file window/sidebar.
5. Observe that the annotation/comment option is not available there.

Expected behavior

The same local PDF should expose consistent annotation behavior across the assistant-link viewer and the file-sidebar viewer, or the sidebar should provide an explicit action such as “Open with annotations” / “Open in active chat”.

Actual behavior

The assistant-link path appears to open an annotatable chat-linked viewer, while the file-sidebar path appears to open a read-only preview. There is no obvious way from the sidebar preview to switch into annotation mode.

Why this matters

For non-technical users reviewing PDFs in Codex Desktop, the sidebar is the natural place to find a file. If annotation is only available from assistant-authored links, users may conclude annotation is unavailable or broken for the file.

Possible related issues

This may be adjacent to other local file-link and app-link behavior in Codex Desktop:

• #16228
• #17591

Suggested fixes

1. Use the same annotatable viewer for local PDFs opened from the assistant link and the file sidebar when an active thread exists.
2. Add a sidebar/context-menu action like “Open with annotations” or “Open in active chat”.
3. If the sidebar preview is intentionally read-only, display a small affordance explaining how to open the file in annotation mode.