I have a separate work knowledgebase using org-roam, but occassionally at work I also want to add something into my personal knowledgebase. So having the org-roam-directory set in the org-roam layer isn't enough. I've set a directory local variable for the org-roam personal wiki directory to use.
((nil (eval ngm-journal-mode)) (org-mode (org-roam-directory . "/home/shared/commonplace/")))
3 Hiding certain nodes from the graph
Handy for me to exclude the sitemap that I have generated by org-publish, and the home page. They confuse the node map a bit.
(setq org-roam-graph-exclude-matcher '("sitemap" "index"))