{
  description = "sow-tools / Crucible — NWN build/conversion/sync toolchain (self-contained Go devshell)";

  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

  outputs = { self, nixpkgs }:
    let
      systems = [ "x86_64-linux" "aarch64-linux" ];
      forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
    in
    {
      # Self-contained (D8): a host with ONLY nix can enter this shell and run
      # `make check`. ffmpeg is present because the migrated music pipeline needs
      # it; the scaffold itself is pure stdlib Go.
      devShells = forAllSystems (pkgs: {
        default = pkgs.mkShell {
          name = "sow-tools";
          packages = with pkgs; [
            go
            gopls
            gotools
            ffmpeg
            git
            gnumake
            bashInteractive
            shellcheck
            yamllint
            jq
          ];
          shellHook = ''
            export GOCACHE="$PWD/.cache/go-build"
            echo "sow-tools / Crucible devshell (self-contained). $(go version 2>/dev/null)"
            echo "  make check   go vet + go test + shellcheck + yamllint"
            echo "  make build   build every cmd/* into ./bin"
            echo "  make smoke   build + run the binary smoke test"
          '';
        };
      });
    };
}