Right now it's the VS code keywords only.
I recommended that set because it's much bigger overall, but it reflects only one syntactic category ([builtin functions][0]). We still need [Vim's][1] more general dictionary for high-frequency predicates like `append` and `write`. Merging them into the "primary" set is fine since they're both SWI-Prolog.
[0]: https://github.com/arthwang/vsc-prolog/blob/3fab7b5916c505d55efc1b7556249bbe... [1]: https://github.com/yochem/prolog.vim/blob/master/syntax/prolog.vim