OS/2 used to have that feature. You could flag a folder as a project in the desktop environment. Anything you opened from that folder was part of that project.

OS/2 used to have that feature. You could flag a folder as a project in the desktop environment. Anything you opened from that folder was part of that project. Close the project folder, everything opened from it closes. Open the project folder, everything you had open from it last time opens. And I'm pretty sure (it's been ~20 years since I used it) that it would also hide all everything if you hid the project folder.