Programming

There's languages designed with Capabilities in mind. Like, whatever starts the program gets to decide what functionality is exposed to the running program. It's great for situations where you might run untrusted code and want to, as an example, not allow network access, or filesystem access.

More generally there's also sandboxing techniques that runtimes provide. Webassembly for instance is designed for programs to run in their own memory space with a restricted set of functions and, again, Capabilities. This might be nice if you ever work on a cloud application that allows users to upload their own programs and you want to impose limits on those programs. Think AWS Lambda, except the programs running wouldn't necessarily even have access to the filesystem or be able to make web requests unless the user configures that.

It might be a good design space for even more esoteric areas, like device drivers. Like, why worry if your GPU drivers are also collecting telemetry on your computer if you can just turn off that capability?

There's older applications of sandboxing that are a bit further from what you're asking as well; like, iframes on a webpage; allowing code served from different servers you don't necessarily control to run without needing to worry about them reading access tokens from local storage.

Or even BSD Jails and chroot.

Good question 💖