What a wallet holds

Before paying from a wallet: what address holds of every coin taken here, on every network of its kind that is switched on (or only network), its gas coin there, and what a transfer of each coin costs (fee, in the gas coin, with room to spare; on Solana also the rent of a receiving token account that is not there yet, and the wallet’s own reserve). A transfer of more than amount, or without fee in the gas coin, would fail. chainSymbol is the contract’s own symbol, the one a wallet lists the coin under (EIP-747). Public chain data read for the address given, from public nodes; nothing is stored. A network whose node did not answer has ok: false. Answers are kept 20 s (fresh: true reads again after 5 s); 20 asks a minute per account.