feat: add NixOS support with flake.nix and installer detection

.envrc

@@ -0,0 +1 @@
+use flake

flake.nix

@@ -0,0 +1,40 @@
+{
+  description = "Nerve — self-hosted AI agent runtime";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            # Core tools
+            uv
+            nodejs_22
+            git
+
+            # Native libs for Python wheel builds (bcrypt, cryptography, aiosqlite, etc.)
+            openssl
+            sqlite
+            libffi
+            pkg-config
+          ];
+
+          env = {
+            # Let uv manage Python — don't pull it from Nix
+            UV_PYTHON_PREFERENCE = "only-managed";
+          };
+
+          shellHook = ''
+            # Help native builds find nix-provided libs
+            export LD_LIBRARY_PATH="${pkgs.lib.makeLibraryPath [ pkgs.openssl pkgs.sqlite pkgs.libffi ]}:$LD_LIBRARY_PATH"
+          '';
+        };
+      });
+}

install.sh

@@ -94,6 +94,8 @@ detect_os() {
                         DISTRO="arch"; PKG_MGR="pacman" ;;
                     opensuse*)
                         DISTRO="suse"; PKG_MGR="zypper" ;;
+                    nixos)
+                        DISTRO="nixos"; PKG_MGR="nix" ;;
                     *)
                         DISTRO="${ID:-unknown}" ;;
                 esac
@@ -115,6 +117,17 @@ detect_os() {
     esac
 }
 
+# --- NixOS helper ---
+
+nixos_require() {
+    local tool="$1"
+    if command_exists "$tool"; then return 0; fi
+    error "$tool is required but not found."
+    error "On NixOS, enter the dev shell first:  nix develop"
+    error "Or install $tool in your system/user profile."
+    exit 1
+}
+
 # --- Dependency: git ---
 
 ensure_git() {
@@ -123,6 +136,8 @@ ensure_git() {
         return
     fi
 
+    if [ "$DISTRO" = "nixos" ]; then nixos_require git; return; fi
+
     info "git is not installed"
     if [ "$HAS_SUDO" = "0" ] && [ "$OS" = "linux" ]; then
         error "git is required but sudo is not available. Install git manually and re-run."
@@ -162,6 +177,8 @@ ensure_uv() {
         return
     fi
 
+    if [ "$DISTRO" = "nixos" ]; then nixos_require uv; return; fi
+
     info "Installing uv (Python package manager)..."
     curl -LsSf https://astral.sh/uv/install.sh | sh
 
@@ -214,6 +231,11 @@ ensure_python() {
     # Last resort: system packages
     warn "uv python install failed. Trying system packages..."
 
+    if [ "$DISTRO" = "nixos" ]; then
+        error "uv python install failed. On NixOS, ensure you're in the dev shell: nix develop"
+        exit 1
+    fi
+
     if [ "$HAS_SUDO" = "0" ] && [ "$OS" = "linux" ]; then
         error "Cannot install Python: no sudo and uv python install failed."
         error "Install Python 3.12+ manually and re-run."
@@ -276,6 +298,8 @@ ensure_node() {
         warn "Node.js $(node --version) is too old (need v${MIN_NODE_MAJOR}+)"
     fi
 
+    if [ "$DISTRO" = "nixos" ]; then nixos_require node; return; fi
+
     info "Node.js ${MIN_NODE_MAJOR}+ is not installed"
 
     if [ "$HAS_SUDO" = "0" ] && [ "$OS" = "linux" ]; then