const DEFAULT_BACKEND = "http://localhost:8765"; chrome.runtime.onMessage.addListener((message, _sender, sendResponse) => { if (message?.type === "SYNC_TO_BACKEND") { syncSession(message.auth, message.backendUrl) .then((result) => sendResponse(result)) .catch((err) => sendResponse({ ok: false, error: err.message })); return true; } });