feat(transaction-pay-controller): Add shared EIP-7702 quote gas estimation by pedronfigueiredo · Pull Request #8145 · MetaMask/core

pedronfigueiredo · 2026-03-09T11:30:28Z

Explanation

Add a shared quote gas estimator that switches between per-transaction and EIP-7702 batch estimation, reuses Across’s ordered submission transaction list at quote time, and falls back to the single-transaction path when batch estimation is unsupported or fails.

References

https://github.com/MetaMask/MetaMask-planning/issues/7098

Checklist

I've updated the test suite for new or updated code as appropriate
I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
I've communicated my changes to consumers by updating changelogs for packages I've changed
I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

Note

Medium Risk
Medium risk because it changes gas limit/cost calculation and batching behavior for Across and Relay, including optional EIP-7702 estimateGasBatch and 7702 batch submission paths. Incorrect estimation ordering or fallback handling could lead to failed transactions or mispriced fees on supported chains.

Overview
Adds a new shared estimateQuoteGasLimits utility to compute per-transaction gas limits, optionally using EIP-7702 estimateGasBatch on supported chains with buffering and safe fallback to individual estimation/fallback gas.

Across quoting now uses a single ordered transaction list (getAcrossOrderedTransactions) and can return a combined gasLimits.batch for multi-tx quotes; Across submission detects this and submits a 7702 batch (gasLimit7702, disables hook/sequential) while omitting per-tx gas.

Relay quoting replaces bespoke single/batch gas estimation with the shared estimator, including placeholder/fallback param population when quote items omit fields, and updates feature-flag helpers by adding getEIP7702SupportedChains (used by isEIP7702Chain). Tests are expanded to cover batch usage, fallbacks, and edge cases (missing swap gas, missing approval chainId, non-7702 chains).

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cryptotavares

Reviewing as @cryptotavares's AI assistant

Overall this is a clean refactor — the shared estimator logic is well-structured, fallbacks are correctly wired, and the batch/individual split in estimateQuoteGasLimits is sound. A few things worth addressing before merge:

Bug: Missing `chainId` fallback in `getAcrossOrderedTransactions`

File: src/strategy/across/transactions.ts + src/strategy/across/across-quotes.ts

getAcrossOrderedTransactions spreads approval transactions directly from the Across API response:

const approvalTransactions = (quote.approvalTxns ?? []).map((approval) => ({
  ...approval,
  kind: 'approval' as const,
  type: TransactionType.tokenMethodApprove,
}));

If the Across API omits chainId on an approval transaction (which the old code explicitly guarded against with quote.approvalTxns?.[index]?.chainId ?? swapTx.chainId), then transaction.chainId will be undefined at runtime despite the type saying number. The gas estimation call in calculateSourceNetworkCost then does:

chainId: toHex(transaction.chainId),  // toHex(undefined) → likely '0x0'

This would target the wrong chain for gas estimation. The cost calculation later in calculateSourceNetworkCost still has the correct fallback (quote.approvalTxns?.[index]?.chainId ?? swapTx.chainId), but that doesn't help if estimation ran against chain 0x0.

The old fallback was intentional. Either:

Add the fallback inside getAcrossOrderedTransactions (pass swapTx.chainId and use approval.chainId ?? swapChainId), or
Add it at the call site in calculateSourceNetworkCost when building the transactions array

Logic concern: `useBuffer` skips buffer when batch API echoes provided gas

File: src/utils/quote-gas.ts (~L105)

const useBuffer =
  gasLimits.length === 1 || paramGasLimits[index] !== gasLimit;

When estimateGasBatch returns per-transaction results (gasLimits.length === transactions.length), useBuffer is false if the batch API returns exactly the value that was passed in via transaction.gas. The intent seems to be "if the chain just echoed back our provided value, don't add a buffer on top." That's a reasonable interpretation, but paramGasLimits[index] is the parsed input gas; if the batch API happens to estimate the same number that was provided (not just echo it), buffer would also be skipped. Is that intentional? Worth adding a comment to clarify.

Minor: `combinePostQuoteGas` EIP-7702 detection heuristic

File: src/strategy/relay/relay-quotes.ts (~L480)

// TODO: Test EIP-7702 support on the chain as well before assuming single gas limit.
const isEIP7702 = gasLimits.length === 1;

A single-step Relay quote (one transaction, individual estimation) also produces gasLimits.length === 1, so this misidentifies it as a 7702 batch and combines the original tx gas into a single limit. I see this has a TODO already — just flagging it as something that becomes more load-bearing now that the shared estimator is in use for both strategies.

One merge blocker (the chainId fallback regression), one question (buffer logic intent), one pre-existing TODO that's worth tracking. Happy to look at a follow-up once the chainId question is resolved.

packages/transaction-pay-controller/src/utils/quote-gas.ts

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packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts

…ation

matthewwalsh0 · 2026-03-11T22:18:31Z

packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts

-    params.length === 1
-      ? await calculateSourceNetworkGasLimitSingle(params[0], messenger)
-      : await calculateSourceNetworkGasLimitBatch(params, messenger);
+  const fallbackChainId = params.find(


These are all marked as required in the Relay type meaning we can assume they are present to simplify the code, and it can throw if they are not provided.

matthewwalsh0 · 2026-03-11T22:18:53Z

packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts

-    params.length === 1
-      ? await calculateSourceNetworkGasLimitSingle(params[0], messenger)
-      : await calculateSourceNetworkGasLimitBatch(params, messenger);
+  const fallbackChainId = params.find(


These are all marked as required in the Relay type meaning we can assume they are present to simplify the code, and it can throw if they are not provided.

matthewwalsh0 · 2026-03-11T22:19:13Z

packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts

+  )?.data;
+
+  const relayGasResult = await estimateQuoteGasLimits({
+    allowBatch: params.every(


Can we just assume this is always the case? Either the quote has valid calls we can process or we should throw?

matthewwalsh0 · 2026-03-11T22:20:14Z

packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts

+    fallbackGas: getFeatureFlags(messenger).relayFallbackGas,
+    fallbackOnSimulationFailure: true,
+    messenger,
+    transactions: params.map((singleParams) => ({


Minor, should we define in variable for readability?

matthewwalsh0 · 2026-03-11T22:20:30Z

packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts

+      from:
+        singleParams.from ??
+        fallbackFrom ??
+        '0x0000000000000000000000000000000000000000',


Also here, we shouldn't need these fallbacks since these aren't optional properties in the params?

matthewwalsh0 · 2026-03-11T22:42:53Z

packages/transaction-pay-controller/src/utils/quote-gas.ts

+  } else if (gas.startsWith('0x')) {
+    parsedGas = new BigNumber(gas.slice(2), 16);
+  } else {
+    parsedGas = new BigNumber(gas);


Are all of these not identical and already handled by the BigNumber constructor with no arguments such as base?

matthewwalsh0 · 2026-03-11T22:55:10Z

packages/transaction-pay-controller/src/utils/quote-gas.ts

+    allowBatch &&
+    transactions.length > 1 &&
+    hasUniformBatchContext(transactions) &&
+    isEIP7702Chain(messenger, firstTransaction.chainId);


This flow and estimateGasBatch isn't just for 7702, it also supports sequential transactions by simulating them together to estimate gas for each one.

The 7702 check and all these fallbacks are already inside estimateGasBatch.

matthewwalsh0 · 2026-03-11T22:56:10Z

packages/transaction-pay-controller/src/utils/quote-gas.ts

+    try {
+      return {
+        ...(await estimateQuoteGasLimitsBatch(transactions, messenger)),
+        usedBatch: true,


Since this flow isn't just for 7702, we could change this to return is7702 to the submit phases know whether the single gas limit is because 7702 worked?

matthewwalsh0 · 2026-03-11T22:57:03Z

packages/transaction-pay-controller/src/utils/quote-gas.ts

+  };
+}
+
+async function estimateQuoteGasLimitsIndividually({


This should just be for single via estimateGas, as the above batch flow already handles multiple non-7702 calls also.

matthewwalsh0 · 2026-03-11T22:57:31Z

packages/transaction-pay-controller/src/utils/quote-gas.ts

+        } as QuoteGasLimit;
+      }
+
+      const gasLimitResult = await estimateGasLimit({


We can't estimate sequential calls since the latter would almost certainly revert since it requires state from the first, such as token approval then swap.

That's why estimateGasBatch does simulation on all the transactions to get sequential gas limits.

pedronfigueiredo self-assigned this Mar 9, 2026

pedronfigueiredo added the team-confirmations label Mar 9, 2026

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jpuri previously approved these changes Mar 11, 2026

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feat(transaction-pay-controller): Add shared EIP-7702 quote gas estim…

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Bug: Missing chainId fallback in getAcrossOrderedTransactions

Logic concern: useBuffer skips buffer when batch API echoes provided gas

Minor: combinePostQuoteGas EIP-7702 detection heuristic

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matthewwalsh0 Mar 11, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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pedronfigueiredo commented Mar 9, 2026 •

edited by cursor bot

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Bug: Missing `chainId` fallback in `getAcrossOrderedTransactions`

Logic concern: `useBuffer` skips buffer when batch API echoes provided gas

Minor: `combinePostQuoteGas` EIP-7702 detection heuristic

matthewwalsh0 Mar 11, 2026 •

edited

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