Auto-balance multiasset transactions

[LudvikGalois]

Previously we gave up when the non-Ada part of a transaction wasn't balanced. We now balance the transaction and correctly update the fee accordingly (since the fee will be higher). We also return an error in the case where the is non-Ada change, but not at least minUTxO change (e.g. in the case where the Ada is already balanced).

Resolves: #3068
Closes: #4453

[Jimbo4350]

LGTM! Liaise with QA and produce a ticket like discussed in the node team call. Only bors the PR when QA has signed off on it

[jonathanknowles]

Hi @LudvikGalois

Just curious: do you have any expectations about how the makeTransactionBodyAutoBalance function should behave if the changeTxOut value is larger that the maximum value size? (As defined by the maxValueSize protocol parameter.)

In cardano-wallet, if we detect that a generated (change) output is larger than the maximum size, we partition it into a number of smaller outputs.

[LudvikGalois]

It's not currently handled here, although it'll be caught when trying to submit. My preference for now is to "give up" and require the user to explicitly make change themselves when building the transaction (my understanding is that this is an edge case in most cases). Manually balancing multiassets is much easier for a human (or script) to do than balancing Ada, because it doesn't need to account for some of what its balancing disappearing as transaction fees.
Multiple change UTxOs is straightforward, but given that we don't know how the user plans to spend it, we might sub-optimally divide it, which could end up costing the user more in fees.

[saratomaz]

I am getting an error when I tried to mint a token (the same test works on latest master):

cardano-cli transaction build 
--mint-script-file test_minting_and_burning_witnesses_ci0_urn_asset_name_True_multisig.script 
--tx-in 898f28715c1fd838f346c523a6977809c5f9726a54ed4dd3c27418c7a00f4463#0 
--tx-out addr_test1vqtp42zsxnuaqt4uw8xh565f8s7tfm98w88sakh9xp7fszg7tksef+3000000+5 11d47abca323a319956e447b7efea9abf91b943c05f2adc42375282a.636f75747473636f696e616d6573 
--mint 5 11d47abca323a319956e447b7efea9abf91b943c05f2adc42375282a.636f75747473636f696e616d6573 
--change-address addr_test1vqtp42zsxnuaqt4uw8xh565f8s7tfm98w88sakh9xp7fszg7tksef 
--witness-override 5 
--out-file test_minting_and_burning_witnesses_ci0_urn_asset_name_True_mint_tx.body 
--babbage-era 
--testnet-magic 42

Command failed: transaction build Error: Negative quantity (-5) in transaction output: TxOutInAnyEra BabbageEra (TxOut (AddressInEra (ShelleyAddressInEra ShelleyBasedEraBabbage) (ShelleyAddress Testnet (KeyHashObj (KeyHash "161aa85034f9d02ebc71cd7a6a893c3cb4eca771cf0edae5307c9809")) StakeRefNull)) (TxOutValue MultiAssetInBabbageEra (valueFromList [(AdaAssetId,18446744073709551615),(AssetId "11d47abca323a319956e447b7efea9abf91b943c05f2adc42375282a" "couttscoinames",-5)])) TxOutDatumNone ReferenceScriptNone)

[Jimbo4350]

@newhoggy was #4450 (comment) resolved?

[newhoggy]

was #4450 (comment) resolved?

Yes. Please see: https://input-output-rnd.slack.com/archives/G011N23CEAE/p1679075401311009?thread_ts=1679052340.879369&cid=G011N23CEAE