I came across an interesting thread on the NixOS subreddit today that helped me fix a problem that I didn’t even know I had with my NixOS system configuration. Every now and then, I’ll try to quickly do nix-shell -p somepackage, and it will fail, because somepackage couldn’t be found. I go and check https://search.nixos.org and it’s there. Huh. Weird. So I just go and add it to my environment.systemPackages to install it, and remove it if it turns out I don’t really need it.