I'm sure the author tried some debugging but it's a bit sad not to see any in the post, instead their workaround is simply presented. I would assume the root o

I'm sure the author tried some debugging but it's a bit sad not to see any in the post, instead their workaround is simply presented. I would assume the root of the difference in behavior comes down to calling fsync when editing files on such a mount. In lieu of having macOS's userland source I grepped through through copies of ed's source from GNU and OpenBSD. I don't see any calls to fsync. Whereas Vim by default does. Note most instances of vi are actually a link to Vim/a minimal version of Vim. Normally I'd test this with with some quick tracing but it appears I've not configured SIP to allow DTrace on my machine and I can't be bothered to reboot right now.