The HydrationEngine (components/system/HydrationEngine.tsx) is an invisible React component mounted at the root of the app tree inside the ThemeProvider.
This component exists solely to run the useHydrationSync hook at the root level. By mounting it inside the provider tree (after authentication and database providers are available), it ensures continuous background synchronization between the Convex cloud and local SQLite.
The component can be extended to render a full-screen blur overlay during Amnesia Mode (complete database rebuild), preventing the user from interacting with stale or empty data.