home: fish: enable nix auto run

home/fish/default.nix

@@ -11,6 +11,12 @@ in
   options.my.home.fish.enable = (mkEnableOption "Fish shell") // { default = true; };
 
   config = mkIf cfg.enable {
+    home.sessionVariables = {
+      # automatically prompt to run program in nix-shell if it's not installed
+      NIX_AUTO_RUN = "1";
+      NIX_AUTO_RUN_INTERACTIVE = "1";
+    };
+
     programs.fish = {
       enable = true;
     };