[Multi-Device Remote] File viewer shows "Unable to load file" on macOS client connected to Windows host

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

26.602.40724

What subscription do you have?

Pro

What platform is your computer?

macOS

What issue are you seeing?

When remoting into a Windows machine using the built-in multi-device connector, the connection establishes successfully and agent terminal execution works fine, but the built-in file viewer fails to render any file contents.

Instead of showing code or diffs, the file viewer webview panel permanently displays a generic "Unable to load file" error. This appears to be a cross-platform boundary issue where the Mac client webview cannot correctly parse or receive the file stream payload formatting sent by the remote Windows app-server.

See attached screenshot for the exact state.

What steps can reproduce the bug?

Attempt to open (click on) a file from the file viewer, or click an in-chat file link provided by the agent.

<img width="607" height="774" alt="Image" src="https://github.com/user-attachments/assets/e5b6aad9-d932-4d00-86a7-64ef263702ab" />

What is the expected behavior?

The file viewer webview should correctly normalize the file paths transmitted by the remote Windows host, decode the stream, and render the file content inline.

Additional information

• This happens exclusively during multi-device remote sessions to Windows hosts; local workspaces on macOS load fine.
• Background operations (terminal actions, agent file edits) are unaffected, suggesting the issue is isolated to the viewer stream/webview path decoding layer.