Due to the file schemes used in GitHub Codespaces and github.dev, browser-based debugging using an extension running in the web extension host doesn't work. If I remember correctly, it did work ~6 Months ago, but have no evidence.
I've raised this as an issue on codespaces and VSCode here:
https://github.com/orgs/community/discussions/44904
microsoft/vscode#171991
However, it isn't clear to me if this is an issue with VS Code, codespaces or the adapter support.
As Mock Debug is used as a template/example for debuggers, especially browser-based debuggers, I'd really appreciate support/guidance as to how we can get this working.