send_token_at split the mint swap's results with
partition(send_denoms.contains(amount)) — membership, not count. When a
change denomination equaled a send denomination (guaranteed when
spending from a proof worth exactly 2x the amount: send [n], change
[n]), the change proofs were serialized INTO the token, and the
receiver redeemed double. Both the wallet send flow and peer-files
purchases mint through this path.
The split now consumes exactly one proof per required send denomination
(everything else returns to the wallet as change) and hard-fails if the
mint returns an incomplete denomination set, so a token can never again
be silently over- or under-packed.
Note: tokens minted BEFORE this fix already contain the extra proofs
and will still redeem at their inflated value.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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