Sending a large amount from a wallet with many small UTXOs could
produce a transaction over the standard relay size limit, surfaced
only as a cryptic "Invalid transaction: Transaction's size is too
high" from builder.Verify() after everything else had already
succeeded — with no way for the user to recover other than manually
picking fewer coins.
Build() now orders spendable UTXOs largest-first and binary-searches
the smallest prefix of them that produces a valid transaction, so it
naturally prefers big coins over dust and avoids the limit whenever a
smaller input set can cover the amount. NBitcoin's own coin selector
already refuses to assemble a combination over the size cap and
reports it via NotEnoughFundsException with a distinctive message
rather than ever handing back an oversized transaction, so that case
is now recognized and translated into a clear, actionable error
instead of being read as "insufficient funds".
davide
1a4fefadc3