Stylix themes per NixOS specialisation: HM follows system automatically

To switch stylix themes without rebuilding, define specialisation.<name>.configuration.stylix.base16Scheme = lib.mkForce "${pkgs.base16-schemes}/share/themes/<scheme>.yaml", plus override = lib.mkForce {} if the default theme uses override. When home-manager runs as a NixOS module and only the stylix NixOS module is imported, HM inherits the system theme via autoImport/followSystem, so you don't need home-manager.users.<u>.stylix in the specialisation. That only applies if the HM stylix module isn't also imported separately. Verify with nix eval of specialisation.<name>.configuration.home-manager.users.<u>.lib.stylix.colors.base00. Activate with /nix/var/nix/profiles/system/specialisation/<name>/bin/switch-to-configuration switch. Note that nixos-rebuild switch or a reboot returns to the default theme.