No Util.writeStorageFile()?

OK. Thanks for your help. I'll just summarize all this for future reference:

function loadSettings() {
  Util.showModal("Loading...");
  Puck.eval(`require("Storage").read(${JSON.stringify("myapp.json")})`,data=>{
    Util.hideModal();
    try {
      settings = JSON.parse(data);
    } catch {
      settings = defaultSettings;
    }
  });
}
function saveSettings() {
  Util.showModal("Saving...");
  Puck.write(`\x10require("Storage").write(${JSON.stringify("myapp.json")},${JSON.stringify(settings)})\n`,()=>{
    Util.hideModal();
  });
}