Add additional USDT approve transaction to account for must-reset-to-0 behavior#413
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Add additional USDT approve transaction to account for must-reset-to-0 behavior#413
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swansontec
approved these changes
Oct 31, 2025
USDT requires an allowance to be zero before it can be nonzero. Most, like 99% of tokens, don't require this behavior. We would ideally check the allowance first before adding any approval transactions to the swap to avoid unnecessary transactions. Instead of adding a bunch of node lists and queries here maybe we could plumb something through the engine or tools to access those node lists.
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| const approvalData = getEvmApprovalData({ | ||
| contractAddress: tokenContractAddress, | ||
| nativeAmount: amount | ||
| }) |
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Bug: Incorrect ERC-20 approve data leading to failures
The createApprovalTx function passes tokenContractAddress to getEvmApprovalData for the contractAddress parameter. The ERC-20 approve function expects the spender address (the recipientAddress) as its first argument. This generates incorrect approval transaction data, leading to failed approval transactions.
| NON_STANDARD_APPROVAL_TOKENS[ | ||
| request.fromWallet.currencyInfo.pluginId | ||
| ].includes(request.fromTokenId) | ||
| ) { |
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Bug: Undefined lookup leads to TypeError on non-ethereum tokens
Accessing NON_STANDARD_APPROVAL_TOKENS for a pluginId other than 'ethereum' results in a TypeError. The lookup returns undefined, and then .includes() is called on that undefined value.
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Adds automatic zero-then-amount ERC20 approvals (for tokens like USDT) and migrates swap flows to support multiple pre-transactions across DEX plugins.
createEvmApprovalEdgeTransactionsto build one or two ERC20 approval pre-txs, including a zero-allowance reset for non-standard tokens (e.g.,ethereumUSDT).getEvmApprovalDatato encodeapprovecalldata locally.preTxwithpreTxsthroughout and pipes them viapendingTxsinmakeSpend/makeTx.lifi,rango,thorchain/swapkit,thorchain/thorchainCommon,unizen: usecreateEvmApprovalEdgeTransactionsand returnpreTxs.spookySwap,tombSwap,velodrome: migrate topreTxshandling.Written by Cursor Bugbot for commit ea8d818. This will update automatically on new commits. Configure here.