Not possible to define context-aware aspects at top-level `den.aspects`.

[vic]

Discussed in #91

^{Originally posted by michaelBelsanti November 14, 2025}
I'm having trouble using the user context in the way demonstrated by the autologin module in the user template.

This is a simplified version of what I'm doing:

{ den, ... }
{
  den.hosts.x86_64-linux.hades.users.quasi = { };
  den.aspects.quasi.includes = [ den.aspects.nushell ];
  den.aspects.nushell =
    { user, ... }:
    {
      nixos =
        { pkgs, ... }:
        {
          environment.systemPackages = [ pkgs.nushell ];
          users.users.${user.userName}.shell = pkgs.bashInteractive;
        };
      homeManager = {
        programs.bash.initExtra = ''
          # https://discourse.nixos.org/t/nushell-as-default-shell/68609/17
          # Some programs launch interactive shells and pretend
          # to use them; such programs always expect a form of POSIX
          # shell.
          #
          # If you don't use programs like that, you can just skip
          # this conditional.
          if ! [ "$TERM" = "dumb" ]; then
            exec nu
          fi
        '';
      };
  };
}

Building hades I end up with this:

error:
       … while calling the 'head' builtin
         at /nix/store/3fis83br4c3xkqh3457ji3w37gihzk6s-source/lib/attrsets.nix:1696:13:
         1695|           if length values == 1 || pred here (elemAt values 1) (head values) then
         1696|             head values
             |             ^
         1697|           else

       … while evaluating the attribute 'value'
         at /nix/store/3fis83br4c3xkqh3457ji3w37gihzk6s-source/lib/modules.nix:1118:7:
         1117|     // {
         1118|       value = addErrorContext "while evaluating the option `${showOption loc}':" value;
             |       ^
         1119|       inherit (res.defsFinal') highestPrio;

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: attribute 'user' missing
       at /nix/store/55z53i8nflvx4y9662rc0b6xb9y43b66-source/lib/modules.nix:685:33:
          684|             "noting that argument `${name}` is not externally provided, so querying `_module.args` instead, requiring `config`"
          685|             config._module.args.${name}
             |                                 ^
          686|           )

I'm sure I'm messing something up with the dependency system, but to me, it looks pretty much the same as the autologin example in the template.

[vic]

I decided that this top-level contextual aspects was an issue to be solved at flake-aspects itself: See vic/flake-aspects#14 and vic/flake-aspects#15