wip: continue migration

aspects/nixpkgs.nix

@@ -0,0 +1,58 @@
+{ self, den, lib, ... }:
+let
+  nixpkgsModule = from:
+    let
+      config = if (from ? host) then from.host else if (from ? home) then from.home else { };
+    in
+    {
+      nixpkgs = {
+        overlays = [
+          self.outputs.overlays.default
+          self.outputs.overlays.stables
+          self.outputs.overlays.modifications
+        ] ++ lib.optionals ((from ? user) || (from ? home)) [
+          (final: prev:
+            let
+              additions = final: _: import "${self}/pkgs/config" {
+                inherit self config lib;
+                pkgs = final;
+                homeConfig = if (from ? user) then from.user else if (from ? home) then from.home else { };
+              };
+            in
+            additions final prev
+          )
+        ];
+        config = lib.mkIf (!config.isMicroVM) {
+          allowUnfree = true;
+        };
+      };
+    };
+
+  hostAspect =
+    { host }:
+    {
+      ${host.class} = nixpkgsModule { inherit host; };
+    };
+
+  hostUserAspect =
+    { host, user }:
+    {
+      ${host.class} = nixpkgsModule { inherit host user; };
+    };
+
+  homeAspect =
+    { home }:
+    {
+      ${home.class} = nixpkgsModule { inherit home; };
+    };
+
+in
+{
+  den.provides.nixpkgs = den.lib.parametric.exactly {
+    includes = [
+      hostAspect
+      hostUserAspect
+      homeAspect
+    ];
+  };
+}