How the app finds your funds
The app reads Announcement events from the vault since its deployment block, checks each one with your viewing key, and keeps the stealth addresses that belong to you. It then reads sharesOf for each.
Shares and value
Displayed HYDD = shares × totalBacking / totalShares (with virtual shares to prevent rounding attacks). The value per share only goes up as fees are donated.
What stays on your device
Keys and the list of discovered stealth addresses stay in your browser. Clearing site data only clears the cache — signing again with the same wallet recovers everything from chain data.