[SDK] Feature: Add support for forcing legacy transactions in chain configuration

packages/thirdweb/src/chains/types.ts

@@ -1,3 +1,5 @@
+import type { FeeType } from "../transaction/prepare-transaction.js";
+
 /**
  * @chain
  */
@@ -26,6 +28,7 @@ export type ChainOptions = {
     increaseZeroByteCount?: boolean;
   };
   faucets?: Array<string>;
+  feeType?: FeeType;
 };
 
 /**

packages/thirdweb/src/gas/fee-data.ts

@@ -3,7 +3,10 @@
 import { eth_getBlockByNumber } from "../rpc/actions/eth_getBlockByNumber.js";
 import { eth_maxPriorityFeePerGas } from "../rpc/actions/eth_maxPriorityFeePerGas.js";
 import { getRpcClient } from "../rpc/rpc.js";
-import type { PreparedTransaction } from "../transaction/prepare-transaction.js";
+import type {
+  FeeType,
+  PreparedTransaction,
+} from "../transaction/prepare-transaction.js";
 import { resolvePromisedValue } from "../utils/promise/resolve-promised-value.js";
 import { toUnits } from "../utils/units.js";
 import { getGasPrice } from "./get-gas-price.js";
@@ -50,11 +53,13 @@
   transaction: PreparedTransaction,
 ): Promise<FeeDataParams> {
   // first check for explicit values
-  const [maxFeePerGas, maxPriorityFeePerGas, gasPrice] = await Promise.all([
-    resolvePromisedValue(transaction.maxFeePerGas),
-    resolvePromisedValue(transaction.maxPriorityFeePerGas),
-    resolvePromisedValue(transaction.gasPrice),
-  ]);
+  const [maxFeePerGas, maxPriorityFeePerGas, gasPrice, feeType] =
+    await Promise.all([
+      resolvePromisedValue(transaction.maxFeePerGas),
+      resolvePromisedValue(transaction.maxPriorityFeePerGas),
+      resolvePromisedValue(transaction.gasPrice),
+      resolvePromisedValue(transaction.feeType),
+    ]);
 
   // Exit early if the user explicitly provided enough options
   if (maxFeePerGas !== undefined && maxPriorityFeePerGas !== undefined) {
@@ -63,6 +68,7 @@
       maxPriorityFeePerGas,
     };
   }
+
   if (typeof gasPrice === "bigint") {
     return { gasPrice };
   }
@@ -71,6 +77,7 @@
   const defaultGasOverrides = await getDefaultGasOverrides(
     transaction.client,
     transaction.chain,
+    feeType,
   );
 
   if (transaction.chain.experimental?.increaseZeroByteCount) {
@@ -113,20 +120,27 @@
 export async function getDefaultGasOverrides(
   client: ThirdwebClient,
   chain: Chain,
+  feeType?: FeeType,
 ) {
-  // if chain is in the force gas price list, always use gas price
-  if (!FORCE_GAS_PRICE_CHAIN_IDS.includes(chain.id)) {
-    const feeData = await getDynamicFeeData(client, chain);
-    if (
-      feeData.maxFeePerGas !== null &&
-      feeData.maxPriorityFeePerGas !== null
-    ) {
-      return {
-        maxFeePerGas: feeData.maxFeePerGas,
-        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas,
-      };
-    }
+  // give priority to the transaction fee type over the chain fee type
+  const resolvedFeeType = feeType ?? chain.feeType;
+  // if chain is configured to force legacy transactions or is in the legacy chain list
+  if (
+    resolvedFeeType === "legacy" ||
+    FORCE_GAS_PRICE_CHAIN_IDS.includes(chain.id)
+  ) {
+    return {
+      gasPrice: await getGasPrice({ client, chain, percentMultiplier: 10 }),
+    };
+  }
+  const feeData = await getDynamicFeeData(client, chain);
+  if (feeData.maxFeePerGas !== null && feeData.maxPriorityFeePerGas !== null) {
+    return {
+      maxFeePerGas: feeData.maxFeePerGas,
+      maxPriorityFeePerGas: feeData.maxPriorityFeePerGas,
+    };
   }
+  // TODO: resolvedFeeType here could be "EIP1559", but we could not get EIP1559 fee data. should we throw?
   return {
     gasPrice: await getGasPrice({ client, chain, percentMultiplier: 10 }),
   };

packages/thirdweb/src/transaction/prepare-transaction.ts

@@ -17,6 +17,7 @@ export type StaticPrepareTransactionOptions = {
   maxFeePerGas?: bigint | undefined;
   maxPriorityFeePerGas?: bigint | undefined;
   maxFeePerBlobGas?: bigint | undefined;
+  feeType?: FeeType | undefined;
   nonce?: number | undefined;
   extraGas?: bigint | undefined;
   // eip7702
@@ -34,6 +35,8 @@ export type StaticPrepareTransactionOptions = {
   };
 };
 
+export type FeeType = "legacy" | "eip1559";
+
 export type EIP712TransactionOptions = {
   // constant or user input
   gasPerPubdata?: bigint | undefined;