{
  description = "gotta-scroll-fast (gsf) - host-side scroll acceleration toolkit";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    let
      eachSystem = flake-utils.lib.eachDefaultSystem;
    in
    eachSystem (system:
      let
        pkgs = import nixpkgs {
          inherit system;
          config.allowUnfree = false;
        };
      in {
        devShells.default = pkgs.mkShell {
          packages = with pkgs; [
            rustc
            cargo
            rustfmt
            clippy
            rust-analyzer
            rustPlatform.rustLibSrc

            pkg-config
            gcc
            clang
            gnumake
            git

            evtest
            libinput
            wev

            jq
            ripgrep
            fd
            jj
          ];

          shellHook = ''
            export RUST_SRC_PATH="${pkgs.rustPlatform.rustLibSrc}"

            echo
            echo "✅ gsf dev shell ready"
            echo "   Rust: $(rustc --version)"
            echo "   Cargo: $(cargo --version)"
            echo "   JJ: $(jj --version | head -n1)"
            echo
            if [ -e /dev/uinput ]; then
              echo "uinput: present at /dev/uinput"
              ls -l /dev/uinput
            else
              echo "uinput: /dev/uinput not found"
              echo "        enable with: boot.kernelModules = [ \"uinput\" ];"
            fi
            echo
          '';
        };
      });
}