resolveGasData method

@override Future<ResolvedGasData?> resolveGasData(TransactionBlockDataBuilder data)

One-shot server-side gas resolution for a fully input-resolved transaction: the server selects the gas coin and computes the budget (gRPC simulate with doGasSelection). Returns null when the transport does not support it (e.g. JSON-RPC); the builder then falls back to local coin selection + a budget dry-run.

Implementation

@override
Future<ResolvedGasData?> resolveGasData(
    TransactionBlockDataBuilder data) async {
  // Structured message (not BCS, which cannot express an unset budget) +
  // `doGasSelection` — mirrors Mysten's TS gRPC `resolveTransactionPlugin`.
  // Omit any preset (e.g. dApp-supplied) budget so the node estimates it
  // rather than selecting coins to satisfy that budget.
  final grpcTx = transactionDataToGrpcTransaction(data, includeBudget: false);
  final sim = await core.simulateStructured(
    grpcTx,
    doGasSelection: true,
    readMask: const [
      'transaction.transaction.gas_payment',
      'transaction.effects.status',
    ],
  );
  final status = sim.transaction.effects.status;
  if (!status.success) {
    throw StateError(
        'Gas resolution simulation failed: ${status.error.description}');
  }
  final gp = sim.transaction.transaction.gasPayment;
  final budget = BigInt.parse(gp.budget.toString());
  if (gp.objects.isEmpty) {
    // The node selected no gas coin (an address-balance PTB it deems
    // gasless-capable). Executing without a gas coin additionally requires a
    // ValidDuring expiration, which this resolution path does not manage —
    // gasless sends are built explicitly via `SuiGrpcCompat.setGaslessGas`.
    // Fall back to local gas selection here so the transaction stays valid.
    return null;
  }
  return ResolvedGasData(
    budget: budget,
    price: gp.hasPrice() ? BigInt.parse(gp.price.toString()) : null,
    payment: gp.objects
        .map((o) => SuiObjectRef(o.digest, o.objectId, o.version.toInt()))
        .toList(),
  );
}