I am developing a LINE-based service for users in Japan. With each user's explicit consent, our backend would read their selected iCloud calendars and send event reminders through LINE. Users would not be required to install a native iOS or macOS app. Apple's support article describes Apple Account authorization for supported third-party apps: https://support.apple.com/en-us/121539 Is this authorization available to a web service with this architecture? What are the eligibility requirements, application process, and Calendar integration documentation? If it is not available, does Apple officially support server-side CalDAV access using a user-generated app-specific password for this use case? What requirements and limitations apply to credential handling, access scope, and synchronization frequency? Do the requirements differ between reading calendars and potentially creating or updating events in the future? If this architecture is not supported, is there another documented integration path? I would appreciate links to the relevant documentation or the appropriate technical contact.