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Transaction Submission Timing

It is recommended that transactions returned by the create-tx API be signed and submitted within 30 seconds. When response.tx is submitted within this window, the likelihood of successful order execution exceeds 99.9%. There is no explicit time-to-live (TTL) on the transaction itself — i.e., the period between receiving the create-tx response and submitting it on-chain. Transactions may remain valid for extended periods, especially when no pre-order-swap is involved or the pre-order-swap is between stablecoins.

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Handling Operating Expense Fluctuations

When the prependOperatingExpenses parameter is enabled, special attention must be paid to how token approval amounts are set. If the allowance exactly matches response.estimation.srcChainTokenIn.amount and there’s a delay — typically more than a minute — before submitting response.tx, operating expenses may increase. In that case the estimate should be refreshed. If the updated expense exceeds the approved amount, an additional approval step is required, degrading the experience.

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Recommendation

  • Set token allowance to infinity if user experience allows
  • Or add a 30% buffer when setting the allowance to absorb changes
const { approximateOperatingExpense } = response.estimation.srcChainTokenIn;
const approveAmount = srcChainTokenInAmount + approximateOperatingExpense * 1.3;
This ensures the approved amount remains sufficient even if gas costs or execution fees rise before submission.
You can find more examples in the code reference