The course tool is one extension, full screen

You're teaching data cleaning, not VS Code. Spawn each student's editor with ?extension=PUBLISHER.NAME and the file explorer disappears: the instance opens showing only that extension's UI. Students see the tool the course is actually about, isolated: their own instance, their own settings, nothing to get lost in. The lesson page iframes it, so the tool sits inside the course material instead of beside it.

Compare the first Tuesday of any tools course: forty laptops, forty installs, three operating systems, one hour gone. Here the install step is a query parameter: and the environment underneath is still a real machine when week six needs the rest of it.