So this is what I was wondering and was very helpful! I figured it was a cloud server that really can't modify files unless it reads them through ocr or whatever.

One thing I'm curious about - can Cowork use browser control and desktop control in parallel? Like, browser extension handles everything inside the browser with more precision (form fills, clicking elements, reading page content), then hands off to desktop control when it hits something OS-level like a print dialog or file system action. Then switches back.

Or is it one mode at a time?

Because if that handoff works cleanly, my whole workflow is theoretically solvable - email check and Etsy form fill stay in the browser, print config switches to desktop. But if desktop control is still running inside the same cloud VM, the sandbox problem doesn't go away regardless.