Define overlays properly

flake.nix

@@ -87,15 +87,15 @@
       };
 
       perSystem = { self', system, pkgs, lib, config, inputs', ... }: {
+        # NOTE: These overlays apply to the Nix shell only. See `nix.nix` for
+        # system overlays.
         _module.args.pkgs = import inputs.nixpkgs {
           inherit system;
           overlays = [
             inputs.jenkins-nix-ci.overlay
-            inputs.nixd.overlays.default
-            inputs.nuenv.overlays.default
-            inputs.nixci.overlays.default
           ];
         };
+
         packages.default = self'.packages.activate;
         devShells.default = pkgs.mkShell {
           buildInputs = [

home/terminal.nix

@@ -10,10 +10,9 @@
     # Useful for Nix development
     nix-output-monitor
     devour-flake
+    nixci
     nil
-    # nixd FIXME: why does this not work?
-    flake.inputs.nixd.packages.${pkgs.system}.nixd
-    flake.inputs.nixci.packages.${pkgs.system}.default
+    nixd
 
     nixpkgs-fmt
     shfmt

nixos/nix.nix

@@ -10,6 +10,9 @@
     overlays = [
       flake.inputs.nuenv.overlays.nuenv
       (self: super: { devour-flake = self.callPackage flake.inputs.devour-flake { }; })
+      flake.inputs.nixd.overlays.default
+      flake.inputs.nuenv.overlays.default
+      flake.inputs.nixci.overlays.default
     ];
   };