Skip to content

Walkthrough Guide


GitHub Repo can be found here:

Getting Started

SDK for XGA bidders and users. This guide provides information on how to interact with the auction contracts and the L2 RPC endpoints. The codebase can be found here to follow along:



  • Private transactions and bundles can be passed to beta blocks through the deployed OpenBidder.
  • Beta transactions can be constructed and submitted with provided cast or python libs.

Convenience Setup

Environment vars

Copy .env.example to .env and change as necessary. Holesky Testnet and mainnet details have been provided.

Beta Transactions

MaxFeePerGas = 0 An important difference with beta block transactions is that the MaxFeePerGas is set to zero. Instead this fee is set for the L2 bid.

Construct and sign a beta transaction

Make sure to setup env vars before signing txs.


Using Foundry's cast:

#!/usr/bin/env bash
# Script to sign a tx given details

# shellcheck source=/dev/null
set -o allexport; source .env; set +o allexport

# Ensure required environment variables are set
for VAR in "${REQUIRED_VARS[@]}"; do
  if [ -z "${!VAR}" ]; then
    echo "Error: $VAR is not set."
    exit 1

# Get current base fee
echo "Getting current base fee"
BASE_FEE=$(cast base-fee --rpc-url "$RPC_L1" latest)
if [ -z "$BASE_FEE" ]; then
  echo "Error: Failed to get base fee."
  exit 1

# Sign TX
echo "Signing tx"
TX=$(cast mktx --rpc-url "$RPC_L1" --private-key "$PRIVATE_KEY" "$TX_TO" "$TX_SIG" "${TX_ARGS[*]}" --value "$TX_VALUE" --priority-gas-price 0 --gas-price $((2 * BASE_FEE)))
if [ -z "$TX" ]; then
  echo "Error: Failed to sign transaction."
  exit 1
echo "$TX"

# Estimate gas
echo "Estimating gas"
AMOUNT_OF_GAS=$(cast estimate --rpc-url "$RPC_L1" "$TX_TO" "$TX_SIG" "${TX_ARGS[*]}" --value "$TX_VALUE")
if [ -z "$AMOUNT_OF_GAS" ]; then
  echo "Error: Failed to estimate gas."
  exit 1


Using python:

poetry run python sign-eth-tx-py/ <contract> <value> <function_sig> <args>


Before bidding, you will need to bridge ETH to L2 for bids.

# Fund L2 address by sending ETH to the bridge address.
cast send -i $L1_BRIDGE --value 0.01ether --rpc-url $L1_RPC_URL --private-key $PRIVATE_KEY

# Confirming the bridged Holesky ETH on L2
cast balance $WALLET_ADDRESS --rpc-url $L2_RPC_URL

Using OpenBidder

Make sure to setup env vars before using open bidder, including WEI_PER_GAS. Scripts are provided for submitting a private transaction to OpenBidder.

Using cast:


Using python:

poetry run beta_bundles_py/

RPC Endpoints

  • L2 RPC:

  • Beta bundle RPC:

    • Description: Beta bundle submission RPC
    • URL:
    • Method: mev_sendBetaBundle
    • Parameters:
      • txs: List of txs as bundle e.g. [0x2323...,]
      • slot: slot number e.g. "11282389"
    • ChainId: 1
  • L2 RPC (Holesky Testnet):

  • Beta bundle RPC (Holesky Testnet):

    • Description: Beta bundle submission RPC
    • URL:
    • Method: mev_sendBetaBundle
    • Parameters:
      • txs: List of txs as bundle e.g. [0x2323...,]
      • slot: slot number e.g. "11282389"
    • ChainId: 17000

Bundle JSON Requests and Responses

Example JSON request

    "jsonrpc": "2.0",
    "method": "mev_sendBetaBundle",
    "params": [
        "txs": [0x... ],
        "slot": "1001"
    "id": 8

Example JSON response

    "jsonrpc": "2.0",
    "id": 1,
    "method": "mev_sendBetaBundle",
    "result": "0x79e5cba7876f532218ac35a357209800be2362dd2e3f1e6dc5974698f0d7cee4",

Contracts Addresses

L1 Addresses

Contract Address
L1StandardBridge 0x490B959870889D5FA0B329431683B8B3e850DD95
L1StandardBridge (Holesky Testnet) 0x3Ae5Ca0B05bE12d4FF9983Ed70D86de9C34e820C

L2 Addresses

Contract Address
WETH 0x4200000000000000000000000000000000000006
Auctioneer 0x86Bc75A43704E38f0FD94BdA423C50071fE17c99
SettlementHouse 0x80C5FfF824d14c87C799D6F90b7D8e0a715bd33C
Accountant 0xE9B82BD9e839f1087d4017b4F7E928E0CADB2AF9
Auctioneer (Holesky Testnet) 0x82052435119AedBEC6e237B5414880bF388F1B63
SettlementHouse (Holesky Testnet) 0x513844F4425d54beC19B0594AE072e49bEbBF388
Accountant (Holesky Testnet) 0x4641748a26D6fca7C11B0366C443dc83d6eb6Be1


Only registered bidders can participate in the auction. Operators can onboard new bidders through the contract. Please contact Mev Protocol to proceed.

The following code snippet uses Foundry as example.

Manual bidding

Wrap ETH for bidding

cast send $WETH "deposit()" --value 1000gwei --private-key $PRIVATE_KEY --rpc-url $L2_RPC_URL

# allow Auctioneer to spend WETH
cast send $WETH "approve(address,uint256)" $AUCTIONEER $(cast max-uint) --private-key $PRIVATE_KEY --rpc-url $L2_RPC_URL

Get slot number of open auctions

cast call $AUCTIONEER "getOpenAuctions()" --rpc-url $L2_RPC_URL

Place a bid

To check for bidderId when registered, call IdMap on the contract:

function IdMap(address bidder) external view returns (uint8 id);

Bids are packed by price, amount, bidderId

* @dev Packed Bid details into a uint256 for submission.
* @param bidPrice Price per item.
* @param itemsToBuy Items to buy in the auction.
* @param bidderId Id for bidder
* @return packedBid for auction submission
function packBid(uint256 bidPrice, uint256 itemsToBuy, uint256 bidderId)
    returns (uint256 packedBid);

For example:

# Packing a bid for 21,000 gas and 0.01 gwei per gas
cast call $AUCTIONEER \
    "packBid(uint128,uint120,uint8)" 0.01gwei 21000 $(cast call $AUCTIONEER "IdMap(address)" $WALLET_ADDRESS --rpc-url $L2_RPC_URL) \
  --rpc-url $L2_RPC_URL

# Placing a bid
cast send $AUCTIONEER \
  "bid(uint256,uint256[] memory)" SLOT_NUMBER ["0x...(Packed Bid)"] \
  --private-key $PRIVATE_KEY \
  --rpc-url $L2_RPC_URL

Winning bid info

After an auction is closed, bidders can query their bid results:

 * @dev Retrieve information about a bidder after auction settlement.
 * @param slot The slot identifier of the auction.
 * @param bidder The address of the bidder for whom information is requested.
 * @return itemsBought The number of items bought by the bidder in the specified auction.
 * @return amountOwed The amount owed by the bidder for the items bought in the specified auction.
 * Requirements:
 * - The auction must have been settled.
 * - The provided `bidder` address must be valid and have participated in the auction.
function getBidderInfo(uint256 slot, address bidder)
    returns (uint120 itemsBought, uint128 amountOwed);
cast call $AUCTIONEER \
  "getBidderInfo(uint256,address)" SLOT_NUMBER $WALLET_ADDRESS \
  --rpc-url $L2_RPC_URL

Contract bidding

Bidder contract requirements:

  • Sufficient WETH balance and approval
  • Registered by operator
  • Implement Bidder interface

A minimal viable bidder is provided below, this contract will bid for every opened auctions:

/// SPDX-License-Identifier: UPL-1.0
pragma solidity ^0.8.25;

import {WETH} from "solmate/tokens/WETH.sol";
import {ERC6909} from "solmate/tokens/ERC6909.sol";

interface Bidder {
     * @dev Get the bid from a bidder for a specific slot and round.
     * @param slot The auction slot.
     * @return packedBids Array of bids (in a packed format). uint256(uint128(bidPrice),uint120(itemsToBuy),uint8(bidderId))
    function getBid(uint256 slot) external view returns (uint256[] memory packedBids);

interface SettlementHouse {
    function submitBundle(uint256 slot, uint256 amount, bytes32[] calldata hashes) external;

/// @title MockBidder
contract MockBidder is Bidder {
    uint256[] public bids;
    ERC6909 auctioneer;
    SettlementHouse house;
    WETH weth;

    constructor(WETH _weth, address _auctioneer, address settlement) {
        weth = _weth;
        auctioneer = ERC6909(_auctioneer);
        house = SettlementHouse(settlement);
        weth.approve(_auctioneer, type(uint256).max);

    function setBids(uint256[] memory newBids) public {
        bids = newBids;

    function getBid(uint256) external view returns (uint256[] memory packedBids) {
        return bids;

    function submit(uint256 slot, uint256 amount, bytes32[] calldata hashes) external {
        auctioneer.approve(address(house), slot, amount);
        house.submitBundle(slot, amount, hashes);

Send Tx and Bundles

Check gas token balance for the slot

cast call $AUCTIONEER \
  "balanceOf(address,uint256)" $WALLET_ADDRESS SLOT_NUMBER \
  --rpc-url $L2_RPC_URL

Build and sign transaction on L1

  • Priority fee MUST be ZERO
  • RPC URL should be L1
  • Return signed transaction
# trasnfer 0.01 ether to self
cast mktx $WALLET_ADDRESS \
  --value 0.01ether \
  --priority-gas-price 0 \
  --private-key $PRIVATE_KEY \
  --rpc-url $L1_RPC_URL

Submit Tx to Beta Bundle RPC

Use the mev_sendBetaBundle method to send the bundle to L1 RPC. The bundle will be stored in L1 RPC, and L1 RPC will return the bundle hash.

curl -X POST \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"mev_sendBetaBundle","params":[{"slot": "SLOT_NUMBER","txs":["0x..SIGNED TX"]}]}' \

Pay gas token for the bundle on L2

 * @dev Function to submit a bundle of transactions.
 * @param slot The slot of the futures token being deposited
 * @param amountOfGas Amount of futures tokens to deposit
 * @param bundleHashes List of bundle hashes
function submitBundle(uint256 slot, uint256 amountOfGas, bytes32[] calldata bundleHashes) external

Submit the bundle hash to SettlementHouse. During this process, the submitBundle in SettlementHouse will check and burn future Gas tokens.

  "submitBundle(uint256,uint256,bytes32[])" SLOT_NUMBER GAS_TOKEN_AMOUNT ["0x..BUNDLE_HASH"] \
  --private-key $PRIVATE_KEY \
  --rpc-url $L2_RPC_URL

The block builder will query the bundle hash in the SettlementHouse contract. If a bundle in the bundle pool is in the SettlementHouse contract, it will be included in the beta block by the block builder.