devshell/nix/repo/devShells.nix

{inputs, ...}: let
  inherit (inputs) pkgs devshell;
in {
  default = devshell.mkShell {
    packages = [
      pkgs.alejandra
    ];
    env."HELLO".value = "world!";
    enterShellCommands.test = {
      text = "echo Hello $HELLO";
      deps = ["env"];
    };
  };
}