What I’d prefer to atomicity is automatic file versioning such that a file descriptor opened at time t0 always points to the same contents, unless you refresh i

What I’d prefer to atomicity is automatic file versioning such that a file descriptor opened at time t0 always points to the same contents, unless you refresh it. You’d also need CoW and/or writing patches rather than rewriting the whole file and a GC/compactor for cleaning up transient versions of a file. The workflows this would be enable is that, when vim wants syntax checking, it writes a transient version of the file to the fs without updating the “HEAD” pointer and then hands a fd to the syntax checker that points to that new transient version.