update dev runtime

flake.nix

@@ -0,0 +1,23 @@
+{
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs = { self, nixpkgs }: let
+    systems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+    forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
+  in {
+    devShells = forAllSystems (pkgs: {
+      default = pkgs.mkShell {
+        packages = with pkgs; [
+          uv python312
+          (writeShellScriptBin "serve" ''
+            python generate.py && python watch.py
+          '')
+        ];
+        shellHook = ''
+          uv sync
+          source .venv/bin/activate
+        '';
+      };
+    });
+  };
+}