redeemable converted to collateral at the preview's price, in BTC wei, fee included.
The fee on that collateral at the live rate, redemptionRate * collateralDrawn / 1e18, the
contract's own formula (BorrowerOperations.sol:499-508), in BTC wei.
previewRedeem(...).redeemable at the send margin: what the SDK's walk of the sorted list expected
one call to redeem. Not getRedemptionHints's truncatedAmount, which answers a different
question and over-reports whenever a later partial cancels (MK-048, MK-241).
Figures computed BEFORE the transaction was sent (MK-241). An estimate is all they are, and the name says so: the redemption settles against the chain at inclusion, and SettledRedemption is what it did.