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Use chain gas price for L2 cost estimates and funding #5

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48 changes: 36 additions & 12 deletions scripts/deploy-predeploys.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -203,12 +203,19 @@ function formatEther(wei: bigint): string {
async function gasEstimateOnL2(params: {
deployments: PreSignedDeployment[]
rpcUrl: string
}): Promise<GasEstimateResult[]> {
}): Promise<{ results: GasEstimateResult[]; chainGasPrice: bigint }> {
const { deployments, rpcUrl } = params
const provider = new JsonRpcProvider(rpcUrl)
const results: GasEstimateResult[] = []

// Fetch the chain's current gas price so we can produce accurate cost estimates.
// Pre-signed txs embed a gas price (e.g. 100 gwei) that may differ wildly from the
// L2's actual pricing — especially on zkSync-style chains with a different gas model.
const feeData = await provider.getFeeData()
const chainGasPrice = feeData.gasPrice ?? BigInt(0)

console.log('\n[L2] Running gas estimation...')
console.log(` Chain gas price: ${formatUnits(chainGasPrice, 'gwei')} gwei`)

for (const deployment of deployments) {
console.log(`\n ${deployment.label}`)
Expand Down Expand Up @@ -256,8 +263,13 @@ async function gasEstimateOnL2(params: {
console.log(` ⚠ Gas estimation failed: ${err.message}`)
}

const estimatedCost = estimatedGasUsed !== null ? estimatedGasUsed * txGasPrice : null
const expectedLeftover = estimatedCost !== null ? maxCost - estimatedCost : null
// Use the chain's actual gas price for cost estimates instead of the gas price
// embedded in the pre-signed tx. On L2s (especially zkSync-style chains) the
// gas model differs from L1 — estimateGas returns L2 gas units which should be
// priced at the L2 gas price, not the 100 gwei baked into the legacy tx.
const effectiveGasPrice = chainGasPrice > BigInt(0) ? chainGasPrice : txGasPrice
const estimatedCost = estimatedGasUsed !== null ? estimatedGasUsed * effectiveGasPrice : null
const expectedLeftover = estimatedCost !== null && maxCost > estimatedCost ? maxCost - estimatedCost : null

results.push({
key: deployment.key,
Expand All @@ -276,7 +288,7 @@ async function gasEstimateOnL2(params: {
})
}

return results
return { results, chainGasPrice }
}

async function deployOnL2(params: {
Expand Down Expand Up @@ -332,22 +344,31 @@ async function deployOnL2(params: {
continue
}

// Estimate actual gas cost for this deployment and use that instead of the
// hardcoded fundingAmount, so we don't over-fund the deployer address.
// The node requires the deployer to hold at least gasLimit × txGasPrice to
// accept the pre-signed transaction. We use gas estimation only to decide
// whether we can send *less* than the hardcoded amount — but we must never
// go below the node's minimum (gasLimit × txGasPrice).
const parsedTx = Transaction.from(deployment.rawTransaction)
const txGasPrice = parsedTx.gasPrice ?? BigInt(0)
const txGasLimit = BigInt(parsedTx.gasLimit)
const nodeMinimum = txGasPrice * txGasLimit
let requiredWei: bigint

try {
const feeData = await provider.getFeeData()
const chainGasPrice = feeData.gasPrice ?? BigInt(0)
const effectiveGasPrice = chainGasPrice > BigInt(0) ? chainGasPrice : txGasPrice

const estimatedGas = await provider.estimateGas({
from: deployment.fundingAddress,
data: parsedTx.data,
value: parsedTx.value
})
// Apply the configurable buffer on top of the estimate
const bufferedGas = estimatedGas * BigInt(100 + gasBuffer) / BigInt(100)
requiredWei = bufferedGas * txGasPrice
const estimatedCost = bufferedGas * effectiveGasPrice
// Never fund below the node's minimum acceptance threshold
requiredWei = estimatedCost > nodeMinimum ? estimatedCost : nodeMinimum
console.log(` Gas estimate: ${estimatedGas.toLocaleString()} (+ ${gasBuffer}% buffer → funding ${formatEther(requiredWei)} ETH vs hardcoded ${deployment.fundingAmount} ETH)`)
} catch (err: any) {
// Fall back to the hardcoded amount if estimation fails
Expand Down Expand Up @@ -493,7 +514,7 @@ async function main() {

// Gas estimate mode: connect to L2, estimate actual costs, check deployer nonces
if (options.gasEstimate) {
const estimates = await gasEstimateOnL2({
const { results: estimates, chainGasPrice } = await gasEstimateOnL2({
deployments,
rpcUrl: options.l2Rpc!
})
Expand Down Expand Up @@ -533,13 +554,16 @@ async function main() {
}

console.log(` Gas price (tx): ${formatUnits(est.txGasPrice, 'gwei')} gwei`)
console.log(` Gas price (chain): ${formatUnits(chainGasPrice, 'gwei')} gwei`)
console.log(` Gas limit (tx): ${est.txGasLimit.toLocaleString()}`)

if (est.estimatedGasUsed !== null && est.estimatedCost !== null && est.expectedLeftover !== null) {
if (est.estimatedGasUsed !== null && est.estimatedCost !== null) {
if (!est.alreadyDeployed) totalEstimated += est.estimatedCost
console.log(` Estimated gas: ${est.estimatedGasUsed.toLocaleString()} used`)
console.log(` Estimated cost: ${formatEther(est.estimatedCost)} ETH`)
console.log(` Expected refund: ${formatEther(est.expectedLeftover)} ETH left in deployer after tx`)
console.log(` Estimated cost: ${formatEther(est.estimatedCost)} ETH (estimatedGas × chain gas price)`)
if (est.expectedLeftover !== null) {
console.log(` Expected refund: ${formatEther(est.expectedLeftover)} ETH left in deployer after tx`)
}
} else if (est.estimateError) {
if (!est.alreadyDeployed) totalEstimated += est.maxCost // fall back to max cost if estimation failed
console.log(` Gas estimate: ⚠ Failed (${est.estimateError})`)
Expand All @@ -553,7 +577,7 @@ async function main() {
console.log(` Hardcoded total: ${formatEther(totalHardcoded)} ETH`)
console.log(` Min required: ${formatEther(totalMaxCost)} ETH (sum of gasPrice × gasLimit per tx)`)
if (totalEstimated > BigInt(0)) {
console.log(` Estimated actual: ${formatEther(totalEstimated)} ETH (likely spend based on gas estimation)`)
console.log(` Estimated actual: ${formatEther(totalEstimated)} ETH (based on chain gas price: ${formatUnits(chainGasPrice, 'gwei')} gwei)`)
}
const hardcodedSavings = totalHardcoded - totalMaxCost
if (hardcodedSavings > BigInt(0)) {
Expand Down