{
  description = "Raylib + RmlUI gamejam dev environment (desktop + wasm)";

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

  outputs = { self, nixpkgs, utils }:
    utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };

        rmluiSrc = pkgs.fetchFromGitHub {
          owner = "mikke89";
          repo = "RmlUi";
          rev = "9c74c4fadc2ad7f1496239e560bab19ca2fe5072";
          hash = "sha256-YZz41ViE3+a0VPypnbJ1Orlf5Hyxd65se5yzyHIY7ZI=";
        };

        rmluiCmakeFlags = [
          "-DRMLUI_LUA_BINDINGS=OFF"
          "-DRMLUI_SVG_PLUGIN=OFF"
          "-DBUILD_SAMPLES=OFF"
          "-DBUILD_TESTING=OFF"
        ];

        wasmFindOverrides = [
          "-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH"
          "-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH"
          "-DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=BOTH"
        ];

        # ---- native RmlUi (shared lib) --------------------------------------
        rmlui = pkgs.stdenv.mkDerivation {
          pname = "rmlui";
          version = "master";
          src = rmluiSrc;
          nativeBuildInputs = [ pkgs.cmake pkgs.pkg-config ];
          buildInputs = [ pkgs.freetype ];
          cmakeFlags = rmluiCmakeFlags ++ [ "-DBUILD_SHARED_LIBS=ON" ];
        };

        # ---- WASM Freetype (static, minimal deps) ---------------------------
        freetypeWasm = pkgs.stdenv.mkDerivation {
          pname = "freetype-wasm";
          version = pkgs.freetype.version;
          src = pkgs.freetype.src;
          nativeBuildInputs = [ pkgs.cmake pkgs.emscripten ];
          dontFixup = true;
          configurePhase = ''
            emcmake cmake -S . -B build \
              -DCMAKE_BUILD_TYPE=Release \
              -DBUILD_SHARED_LIBS=OFF \
              -DFT_DISABLE_ZLIB=TRUE \
              -DFT_DISABLE_BZIP2=TRUE \
              -DFT_DISABLE_PNG=TRUE \
              -DFT_DISABLE_HARFBUZZ=TRUE \
              -DFT_DISABLE_BROTLI=TRUE \
              -DCMAKE_INSTALL_PREFIX=$out
          '';
          buildPhase = "emmake make -C build -j$NIX_BUILD_CORES";
          installPhase = "emmake make -C build install";
        };

        # ---- WASM RmlUi (static) ---------------------------------------------
        rmluiWasm = pkgs.stdenv.mkDerivation {
          pname = "rmlui-wasm";
          version = "master";
          src = rmluiSrc;
          nativeBuildInputs = [ pkgs.cmake pkgs.emscripten ];
          dontFixup = true;
          configurePhase = ''
            emcmake cmake -S . -B build \
              -DCMAKE_BUILD_TYPE=Release \
              -DBUILD_SHARED_LIBS=OFF \
              ${pkgs.lib.concatStringsSep " " rmluiCmakeFlags} \
              ${pkgs.lib.concatStringsSep " " wasmFindOverrides} \
              -DCMAKE_PREFIX_PATH="${freetypeWasm}" \
              -DCMAKE_INSTALL_PREFIX=$out
          '';
          buildPhase = "emmake make -C build -j$NIX_BUILD_CORES";
          installPhase = "emmake make -C build install";
        };

        # ---- WASM raylib (PLATFORM=Web) ---------------------------------------
        raylibWasm = pkgs.stdenv.mkDerivation {
          pname = "raylib-wasm";
          version = pkgs.raylib.version;
          src = pkgs.raylib.src;
          nativeBuildInputs = [ pkgs.cmake pkgs.emscripten ];
          dontFixup = true;
          configurePhase = ''
            emcmake cmake -S . -B build \
              -DCMAKE_BUILD_TYPE=Release \
              -DPLATFORM=Web \
              -DBUILD_EXAMPLES=OFF \
              -DCMAKE_INSTALL_PREFIX=$out
          '';
          buildPhase = "emmake make -C build -j$NIX_BUILD_CORES";
          installPhase = "emmake make -C build install";
        };

        # ---- native toolchain / runtime ---------------------------------------
        nativeBuildTools = with pkgs; [
          cmake
          pkg-config
          clang-tools
        ];

        nativeRuntimeDeps = with pkgs; [
          raylib
          libGL
          libX11
          libXcursor
          libXrandr
          libXinerama
          libXi
          wayland
          libxkbcommon
          rmlui
          freetype
        ];
      in
      {
        devShells.default = pkgs.mkShell {
          nativeBuildInputs = nativeBuildTools;
          buildInputs = nativeRuntimeDeps;
          shellHook = ''
            export C_INCLUDE_PATH="${rmlui}/include:${pkgs.raylib}/include"
            export CPLUS_INCLUDE_PATH="$C_INCLUDE_PATH"
            export LIBRARY_PATH="${pkgs.lib.makeLibraryPath nativeRuntimeDeps}"
            export LD_LIBRARY_PATH="$LIBRARY_PATH:$LD_LIBRARY_PATH"
            echo "native dev shell ready (raylib + rmlui)"
          '';
        };

        devShells.wasm = pkgs.mkShell {
          nativeBuildInputs = [ pkgs.cmake pkgs.emscripten pkgs.python3 ];
          shellHook = ''
            export RAYLIB_WASM="${raylibWasm}"
            export RMLUI_WASM="${rmluiWasm}"
            export FREETYPE_WASM="${freetypeWasm}"
            echo "wasm dev shell ready — configure with:"
            echo "  emcmake cmake -B build-wasm -DPLATFORM=Web \\"
            echo "    -DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH \\"
            echo "    -DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH \\"
            echo "    -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=BOTH \\"
            echo "    -DCMAKE_PREFIX_PATH=\"\$RAYLIB_WASM;\$RMLUI_WASM;\$FREETYPE_WASM\""
            echo "  emmake make -C build-wasm"
          '';
        };

        packages.default = pkgs.stdenv.mkDerivation {
          pname = "gamejam";
          version = "0.1.0";
          src = ./.;
          nativeBuildInputs = nativeBuildTools ++ [ pkgs.makeWrapper ];
          buildInputs = nativeRuntimeDeps;
          cmakeFlags = [ "-DCMAKE_BUILD_TYPE=Release" ];
          postInstall = ''
            wrapProgram $out/bin/gamejam \
              --prefix LD_LIBRARY_PATH : "${pkgs.lib.makeLibraryPath nativeRuntimeDeps}"
          '';
        };

        packages.wasm = pkgs.stdenv.mkDerivation {
          pname = "gamejam-wasm";
          version = "0.1.0";
          src = ./.;
          nativeBuildInputs = [ pkgs.cmake pkgs.emscripten ];
          dontFixup = true;
          configurePhase = ''
            emcmake cmake -S . -B build \
              -DCMAKE_BUILD_TYPE=Release \
              -DPLATFORM=Web \
              ${pkgs.lib.concatStringsSep " " wasmFindOverrides} \
              -DCMAKE_PREFIX_PATH="${raylibWasm};${rmluiWasm};${freetypeWasm}" \
              -DCMAKE_INSTALL_PREFIX=$out
          '';
          buildPhase = "emmake make -C build -j$NIX_BUILD_CORES";
          installPhase = ''
            mkdir -p $out
            cp -r build/*.html build/*.js build/*.wasm $out/ 2>/dev/null || true
            emmake make -C build install || true
          '';
        };
      }
    );
}