{
  description = "beefy-player — a flashy terminal player for internet radio";

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

  outputs =
    { self, nixpkgs }:
    let
      systems = [
        "x86_64-linux"
        "aarch64-linux"
        "x86_64-darwin"
        "aarch64-darwin"
      ];

      forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});

      # Things the app shells out to at runtime: mpv for audio, ffmpeg for the
      # spectrum capture, and parec/pactl from PulseAudio for the monitor source
      # (PipeWire speaks the same protocol).
      runtimeDeps =
        pkgs:
        with pkgs;
        [
          mpv
          ffmpeg
        ]
        ++ lib.optionals stdenv.hostPlatform.isLinux [ pulseaudio ];

      beefy-player =
        pkgs:
        let
          py = pkgs.python3Packages;
        in
        py.buildPythonApplication {
          pname = "beefy-player";
          version = "1.2.2";
          pyproject = true;
          src = self;

          build-system = [ py.hatchling ];

          dependencies =
            with py;
            [
              textual
              rich
              httpx
              numpy
              pillow
            ]
            ++ pkgs.lib.optionals pkgs.stdenv.hostPlatform.isLinux [ dbus-next ];

          nativeBuildInputs = [ pkgs.makeWrapper ];
          nativeCheckInputs = with py; [
            pytestCheckHook
            pytest-asyncio
          ];

          # The suite is offline (catalogues are cached fixtures).
          doCheck = true;

          pythonImportsCheck = [ "beefy_player" ];

          makeWrapperArgs = [
            "--prefix"
            "PATH"
            ":"
            (pkgs.lib.makeBinPath (runtimeDeps pkgs))
          ];

          meta = {
            description = "Flashy terminal player for internet radio, with a live spectrum analyser";
            homepage = "https://tildeforge.dev/beefcarver/beefy-player";
            license = pkgs.lib.licenses.wtfpl;
            mainProgram = "beefy-player";
            platforms = pkgs.lib.platforms.unix;
          };
        };
      # One module body, two install targets: a NixOS system adds the package
      # to environment.systemPackages, Home Manager to home.packages.
      mkModule =
        install:
        {
          config,
          lib,
          pkgs,
          ...
        }:
        let
          cfg = config.programs.beefy-player;
        in
        {
          options.programs.beefy-player = {
            enable = lib.mkEnableOption "beefy-player, a terminal radio player";

            package = lib.mkOption {
              type = lib.types.package;
              default = self.packages.${pkgs.stdenv.hostPlatform.system}.default;
              defaultText = lib.literalMD "the `beefy-player` package from this flake";
              description = "The beefy-player package to use.";
            };
          };

          config = lib.mkIf cfg.enable (lib.setAttrByPath install [ cfg.package ]);
        };
    in
    {
      packages = forAllSystems (
        pkgs:
        let
          pkg = beefy-player pkgs;
        in
        {
          default = pkg;
          beefy-player = pkg;
        }
      );

      apps = forAllSystems (pkgs: {
        default = {
          type = "app";
          program = "${beefy-player pkgs}/bin/beefy-player";
          meta.description = "Flashy terminal player for internet radio";
        };
      });

      checks = forAllSystems (pkgs: {
        beefy-player = beefy-player pkgs;
      });

      devShells = forAllSystems (
        pkgs:
        let
          inherit (pkgs) lib;
        in
        {
          # No FHS needed here: `nix develop` puts libstdc++ on LD_LIBRARY_PATH
          # so uv's manylinux wheels load, unlike the plain `nix-shell` case in
          # shell.nix.
          default = pkgs.mkShell {
            packages = runtimeDeps pkgs ++ [
              pkgs.python3
              pkgs.uv
              pkgs.ruff
              pkgs.git
              pkgs.cacert
            ];

            env = {
              UV_PYTHON = "${pkgs.python3}/bin/python3";
              UV_PYTHON_DOWNLOADS = "never";
              UV_PROJECT_ENVIRONMENT = "${toString ./.}/.venv";
              UV_LINK_MODE = "copy";
              SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
            };

            LD_LIBRARY_PATH = lib.makeLibraryPath [
              pkgs.stdenv.cc.cc.lib
              pkgs.zlib
            ];

            shellHook = ''
              echo "beefy-player dev shell — uv sync, uv run pytest, uv run beefy-player"
            '';
          };
        }
      );

      nixosModules.default = mkModule [
        "environment"
        "systemPackages"
      ];
      nixosModules.beefy-player = self.nixosModules.default;

      homeModules.default = mkModule [
        "home"
        "packages"
      ];
      homeModules.beefy-player = self.homeModules.default;

      formatter = forAllSystems (pkgs: pkgs.nixfmt);

      overlays.default = final: _prev: {
        beefy-player = beefy-player final;
      };
    };
}