{
  description = "Browser emulator for the xteink X3 (ESP32-C3) — QEMU-based, runs any firmware .bin";

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

  outputs =
    { self
    , nixpkgs
    , flake-utils
    ,
    }:
    flake-utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = nixpkgs.legacyPackages.${system};

        # Espressif's QEMU fork (ESP32-C3 SoC). Prebuilt generic-linux binary,
        # made runnable on NixOS with autoPatchelfHook (no FHS/bwrap needed).
        qemu-esp32c3 = pkgs.stdenv.mkDerivation {
          pname = "qemu-esp32c3";
          version = "esp-develop-9.2.2-20260417";
          src = pkgs.fetchurl {
            url = "https://github.com/espressif/qemu/releases/download/esp-develop-9.2.2-20260417/qemu-riscv32-softmmu-esp_develop_9.2.2_20260417-x86_64-linux-gnu.tar.xz";
            hash = "sha256-VH8D4EcBqSy7aZ9/fQFa3B9bXvk8u5TA3ZtxB+LYTnc=";
          };
          sourceRoot = "qemu";
          nativeBuildInputs = [ pkgs.autoPatchelfHook ];
          buildInputs = with pkgs; [ pixman libgcrypt SDL2 zlib libslirp stdenv.cc.cc.lib ];
          installPhase = ''
            mkdir -p $out
            cp -r bin share $out/
          '';
        };

        # `nix run .#run-upstream -- flash.bin [extra qemu args]`
        runScript = pkgs.writeShellScriptBin "xteink-qemu-upstream" ''
          flash="''${1:?usage: run <flash.bin> [qemu args...]}"; shift || true
          exec ${qemu-esp32c3}/bin/qemu-system-riscv32 \
            -machine esp32c3 -L ${qemu-esp32c3}/share/qemu \
            -nographic -drive file="$flash",if=mtd,format=raw "$@"
        '';
      in
      {
        packages.qemu-esp32c3 = qemu-esp32c3;
        packages.default = qemu-esp32c3;

        apps.run-upstream = {
          type = "app";
          program = "${runScript}/bin/xteink-qemu-upstream";
        };

        devShells.default = pkgs.mkShell {
          # Reuse nixpkgs' complete QEMU build environment; Espressif's crypto
          # devices additionally require libgcrypt.
          inputsFrom = [ pkgs.qemu ];
          packages = with pkgs; [
            qemu-esp32c3
            esptool
            gnumake
            git
            libgcrypt
            libslirp
            dosfstools
            mtools
            llvmPackages.clang-unwrapped
            lld
            gcc
          ];
        };
      }
    );
}