``` { pkgs ? import <nixpkgs> {} }: let fhs = if pkgs ? buildFHSUserEnv then pkgs.buildFHSUserEnv else pkgs.buildFHSEnv; fhsEnv = fhs { name = "claudecode-fhs"; targetPkgs = pkgs: [ pkgs.bash pkgs.coreutils pkgs.curl pkgs.zlib pkgs.openssl ]; runScript = "bash"; profile = '' export PATH="$HOME/.local/bin:$PATH" echo "Ensuring latest Claude Code (native installer, no npm)..." curl -fsSL https://claude.ai/install.sh | bash ''; }; in pkgs.mkShell { packages = [ fhsEnv ]; shellHook = '' exec ${fhsEnv}/bin/claudecode-fhs ''; } ```