{
  description = "Bevy + local AI game dev template for macOS with Nix";

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

  outputs =
    {
      self,
      nixpkgs,
      flake-utils,
      rust-overlay,
    }:
    flake-utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = import nixpkgs {
          inherit system;
          overlays = [ (import rust-overlay) ];
        };

        lib = pkgs.lib;

        rustToolchain = pkgs.rust-bin.stable."1.95.0".default.override {
          extensions = [
            "rust-src"
            "rustfmt"
            "clippy"
            "rust-analyzer"
          ];
          targets = [
            "wasm32-unknown-unknown"
          ];
        };

        linuxLibs = lib.optionals pkgs.stdenv.isLinux (
          with pkgs;
          [
            alsa-lib
            libudev-zero
            vulkan-loader
            wayland
            libxkbcommon
            xorg.libX11
            xorg.libXcursor
            xorg.libXi
            xorg.libXrandr
          ]
        );
      in
      {
        devShells.default = pkgs.mkShell {
          packages =
            with pkgs;
            [
              rustToolchain
              pkg-config
              clang
              cmake
              git
              just
              bacon
              cargo-edit
              cargo-watch
              cargo-nextest
              nil
              nixd
              taplo
              imagemagick
              pngquant
              ffmpeg
              jq
              fd
              ripgrep
              tree
              python3
              nodejs_22
              libiconv
            ]
            ++ linuxLibs;

          shellHook = ''
            export RUST_SRC_PATH="${rustToolchain}/lib/rustlib/src/rust/library"
            export LIBCLANG_PATH="${pkgs.llvmPackages.libclang.lib}/lib"
            export CARGO_INCREMENTAL=1
            export RUST_BACKTRACE=1
            export BEVY_ASSET_ROOT="$PWD/assets"

            if [ "$(uname)" = "Darwin" ]; then
              if ! xcode-select -p >/dev/null 2>&1; then
                echo 'error: Xcode Command Line Tools missing. Run: xcode-select --install'
              else
                export SDKROOT="$(xcrun --sdk macosx --show-sdk-path 2>/dev/null || true)"
              fi
            fi

            mkdir -p assets ai/context

            echo "Bevy + AI shell ready"
            echo "rustc: $(rustc --version)"
            echo "cargo: $(cargo --version)"
            echo "node:  $(node --version)"

            # Keep user prompt/plugins by switching interactive sessions to system zsh.
            # This does not affect `nix develop -c ...` non-interactive commands.
            if [ -n "''${PS1:-}" ] && [ -z "''${ZSH_VERSION:-}" ] && [ -z "''${IN_NIX_DEVELOP_SYSTEM_ZSH:-}" ] && [ -x /bin/zsh ]; then
              export IN_NIX_DEVELOP_SYSTEM_ZSH=1
              export SHELL=/bin/zsh
              exec /bin/zsh -i
            fi
          '';
        };
      }
    );
}