One aspect to define them all, and in dependencies.nix bind them.

Den uses the den.default aspect as a backbone for providing shared values, since each Host, User, and Home automatically includes it.

Global Settings

You can use it to define settings that will never change.

den.default.nixos.system.stateVersion = "25.11";
den.default.darwin.system.stateVersion = 6;
den.default.homeManager.programs.vim.enable = true;

Default Dependencies

den.default also serves as the main router for context-aware aspects, a topic we will explore in later sections.

default.includes

As with any aspect, you can make default depend on other aspects, causing them to be included in all Homes, Users, and Hosts. This topic is also explored incrementally in the following sections.

You can also make any aspect include den.default, but be sure to avoid recursion.