Use fish instead of bash as default shell

nixos/modules/common.nix

@@ -24,6 +24,11 @@ in
 
   config = mkMerge [
     {
+      system = {
+        stateVersion = "21.11";
+        configurationRevision = with inputs; mkIf (self ? rev) self.rev;
+      };
+
       home-manager = {
         # Installs packages in the system config instead of in the local profile on activation
         useUserPackages = mkDefault true;
@@ -105,6 +110,12 @@ in
         vim
       ];
 
+      programs = {
+        # This will enable generating completions at build time and prevent home-manager fish from generating them
+        # locally
+        fish.enable = mkDefault true;
+      };
+
       services = {
         kmscon = {
           # As it turns out, kmscon hasn't been updated in years and has some bugs...
@@ -124,11 +135,6 @@ in
           passwordAuthentication = mkDefault false;
         };
       };
-
-      system = {
-        stateVersion = "21.11";
-        configurationRevision = with inputs; mkIf (self ? rev) self.rev;
-      };
     }
     (mkIf config.services.kmscon.enable {
       fonts.fonts = with pkgs; [

nixos/modules/user.nix

@@ -32,6 +32,9 @@ in
           uid = mkDefault 1000;
           extraGroups = mkDefault [ "wheel" ];
           password = mkDefault "hunter2"; # TODO: secrets...
+          shell =
+            let shell = cfg.homeConfig.my.shell;
+            in mkIf (shell != null) (mkDefault' shell);
           openssh.authorizedKeys.keyFiles = [ lib.my.authorizedKeys ];
         };
         # In order for this option to evaluate on its own, home-manager expects the `name` (which is derived from the