import org.openqa.selenium.Cookie;// Add session cookie:
Cookie authCookie = new Cookie("session_token", "jwt_abc123");
driver.manage().addCookie(authCookie);
driver.navigate().refresh(); // Apply cookie
// Clear cookies:
driver.manage().deleteAllCookies();
// LocalStorage via JavaScriptExecutor:
JavascriptExecutor js = (JavascriptExecutor) driver;
js.executeScript("localStorage.setItem('theme', 'dark');");
String token = (String) js.executeScript("return localStorage.getItem('token');");