Bump nixpkgs to unstable; add agenix

flake.nix

@@ -3,12 +3,13 @@
 
 
   inputs = {
-    nixpkgs.url = "nixpkgs/nixos-23.05";
+    nixpkgs.url = "nixpkgs/nixos-unstable";
     impermanence.url = "github:nix-community/impermanence";
+    agenix.url = "github:ryantm/agenix";
   };
 
 
-  outputs = {self, nixpkgs, impermanence}: 
+  outputs = {self, nixpkgs, impermanence, agenix}: 
     let 
       customPackagesModule = {...}: {
         nixpkgs.overlays = 
@@ -18,11 +19,11 @@
           ];
       };
 
-      forAllSystems = function:
+      forAllSystems = fun:
         nixpkgs.lib.genAttrs [
           "x86_64-linux"
           "aarch64-darwin"
-        ] (system: function nixpkgs.legacyPackages.${system});
+        ] (system: fun system);
       
     in
       {
@@ -32,15 +33,19 @@
             modules = [
               customPackagesModule
               impermanence.outputs.nixosModules.impermanence
+              agenix.nixosModules.default
               ./lib/systems/fugitive
             ];
           };
         };
 
-        devShells = forAllSystems (pkgs: {
-          default = pkgs.mkShell {
-            buildInputs = [ pkgs.nixos-rebuild ];
-          };
-        });
+        devShells = forAllSystems (system: 
+          let pkgs = nixpkgs.legacyPackages.${system}; 
+           in
+           {
+            default = with pkgs; mkShell {
+              buildInputs = [ nixos-rebuild agenix.packages.${system}.default ];
+            };
+           });
       };
 }