Max fills in a token's whole balance, cut down to the 18 decimal places the
confirmation screen accepts, or for ETH the exact balance minus the fee
reserve the confirmation screen's balance check gates on. An ETH fee estimate
that finishes after the Send screen was left, or its address, holding or
recipient changed, fills nothing in. The confirmation screen works a max ETH
amount out again from its own fee estimate and signs it with that estimate's
fee fields, so a fee that rose before signing cannot push amount plus fee
above the balance. validateTransfer() still gates every send, the check that
ETH covers a token send's fee included. Where there is nothing to fill in, a
flash message says why.
Model: opus-5-5
