unical_caldav

CalDAV backend for unical, built on the caldav package.

• Events map to VEVENT, tasks to native VTODO (with PERCENT-COMPLETE), so on a task-capable server the engine runs the nativeVtodo strategy and the percentage round-trips natively.
• The caldav package models neither CATEGORIES nor custom X- properties, so this backend reports preservesXProps: false / supportsCategories: false — tags stay in the caller's store. A future revision can inject them through CalendarEvent.rawIcalendar.

final backend = await CalDavBackend.connect(
  baseUrl: 'https://caldav.fastmail.com',
  username: 'me@fastmail.com',
  password: '<app-password>',
);
final engine = SyncEngine(backend: backend, mappings: InMemoryMappingStore());

Google Workspace is not a target for tasks here: Google's CalDAV interface is events-only (it rejects VTODO). Point this backend at a task-capable server (Nextcloud, Fastmail, iCloud). For Google/device use unical_flutter.