vscode-cdn.net not forwarded on Live Share → e.g., vscode-pdf fails

[SichangHe]

I tried to preview a PDF in a VSCode Live Share session, but none of the extensions on the marketplace works. E.g., this is what vscode-odf shows:

I opened up the webview DevTools console and found out the extensions failed to receive the PDF at all:

Pressing the Download button of vscode-pdf reveals the culprit: it sends me to https://vsls+.vscode-resource.vscode-cdn.net/MY_PDF_NAME.pdf#pdfjs.action=download, an unreachable URL.

There are various other error messages about failing to fetch remote embedding cache from https://embeddings.vscode-cdn.net, etc., showing that vscode-cdn.net is not forwarded correctly in Live Share.

Motivation to fix this issue

This issue renders VSCode Live Share strictly inferior to Google Doc, and affects GitHub Codespaces. In #3372, #3624, and #1895, people discovered that PDF and image preview does not work in Live Share. Many more extensions relies on vscode-cdn.net to fetch resources, and they likely all fail in Live Share. In fact, I cannot find any way to view images in Live Share, a fundamental capability.

What was your system configuration?
Product and Version [VS/VSCode]: 1.92.1 eaa41d57266683296de7d118f574d0c2652e1fc4 arm64
OS Version: macOS
Live Share Extension Version: 2024-08-07, 00:11:02
Target Platform or Language: PDF

Please attach logs to this issue: live-share-logs.zip