The Scheme interpreter only runs when compiling a sandbox. It's compiled into a simple non-Turing-complete bytecode, and that's what's consulted on every sysca

The Scheme interpreter only runs when compiling a sandbox. It's compiled into a simple non-Turing-complete bytecode, and that's what's consulted on every syscall. This has been the case since… 10.5 or something. It's always been on the path for BSD code. And Cocoa operations lower to BSD syscalls anyway. There's no system for them to get a "capability" for a directory tree; on the contrary, file descriptors ought to be able to serve as capabilities, but the Sandbox kext stupidly computes the full path for every file that's accessed before matching it against a bunch of regexes. This too has been the case as long as Sandbox has existed. There is a bunch of new stuff in 10.15, mostly involving binary execs (and I don't understand all of it), but I'm pretty sure it doesn't match what you're describing.