feat(transaction-pay): add Across strategy support by pedronfigueiredo · Pull Request #7886 · MetaMask/core

pedronfigueiredo · 2026-02-10T11:23:47Z

Explanation

This PR extracts the Across strategy work on top of the provider-fallback baseline.

It adds:

Across strategy wiring (across strategy type + registration)
Across quote retrieval/parsing/normalization
Across submit flow for approval + swap/deposit execution paths
Across-specific types/constants required for compilation
Minimal selection/config hooks to make Across selectable
Changelog entries for transaction-controller and transaction-pay-controller

References

Addresses: https://github.com/MetaMask/MetaMask-planning/issues/6997

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
Introduces a new external-API-backed quote/submit flow that creates and batches on-chain transactions and adds polling/error handling, which can impact transaction execution correctness. Changes are feature-flag gated and well-covered by tests but touch core pay submission and gas estimation logic.

Overview
Enables MetaMask Pay to use Across as an additional TransactionPayStrategy, including feature-flag driven enablement/config (apiBase, allowSameChain) and default strategy ordering to try Relay then Across.

Implements Across quote retrieval/normalization (/swap/approval), including recipient extraction for transfer-style destinations, fee/dust calculation, and buffered gas estimation with a new reusable estimateGasLimitWithBufferOrFallback helper.

Adds an Across execution path that can submit approval+swap as a batch or single transaction, maps Perps/Predict deposits to new transaction types (perpsAcrossDeposit, predictAcrossDeposit), and optionally polls Across /deposit/status to return the destination hash; updates changelogs and adds extensive unit tests around the new strategy and gas/feature-flag behavior.

^{Written by Cursor Bugbot for commit 43816bc. This will update automatically on new commits. Configure here.}

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

packages/transaction-pay-controller/src/strategy/across/types.ts

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

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

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

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

matthewwalsh0 · 2026-02-13T22:48:19Z

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

+  return getFeatureFlags(messenger).relayFallbackGas;
+}
+
+export async function estimateGasWithBufferOrFallback({


estimateGasLimit?

matthewwalsh0 · 2026-02-13T22:48:34Z

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

  };
 }

+export function getFallbackGas(messenger: TransactionPayControllerMessenger): {


Should this be in feature-flags.ts?

matthewwalsh0 · 2026-02-13T22:49:54Z

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

+    error = caughtError;
+  }
+
+  const fallbackGas = getFallbackGas(messenger);


Debatable whether we should have fallback gas or throw as it implies the transaction would revert?

fallback is now option but off by default

matthewwalsh0 · 2026-02-13T22:51:46Z

packages/transaction-pay-controller/src/utils/feature-flags.ts

+  across?: PayStrategyConfigRaw;
+  relay?: {
+    enabled?: boolean;
+    relayQuoteUrl?: string;


Is this redundant as we already have the top level value?

matthewwalsh0 · 2026-02-13T22:52:54Z

packages/transaction-pay-controller/src/utils/feature-flags.ts

  slippage: number;
 };

+export type PayStrategyConfigRaw = {


Should this be AcrossConfig?

matthewwalsh0 · 2026-02-13T23:25:24Z

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

+    messenger,
+  });
+
+  const max = calculateGasCost({


We also need gas station support here, but can do that in a future PR and re-use the Relay logic.

added a ticket for this

matthewwalsh0 · 2026-02-13T23:32:15Z

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

+  request: QuoteRequest,
+): Promise<TransactionPayQuote<AcrossQuote>['fees']['sourceNetwork']> {
+  const { from } = request;
+  const { swapTx } = quote;


Do we also need to include gas cost of approvalTxns?

matthewwalsh0 · 2026-02-13T23:34:19Z

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

+  const chainId = toHex(params.chainId);
+  const value = toHex(params.value ?? '0x0');
+
+  const gas = await estimateGasWithBuffer(


We don't want to duplicate the gas logic again, but store the gas limits in the quote to use during submit, so we know the network fees will match.

matthewwalsh0 · 2026-02-13T23:34:50Z

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

+    data: params.data,
+    from,
+    gas: toHex(gas),
+    maxFeePerGas: normalizeOptionalHex(params.maxFeePerGas),


Can they not return gas fee properties?

not sure I understand the question here, it's simply normalising to hex if needed.

matthewwalsh0 · 2026-02-13T23:37:05Z

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

+  }
+
+  await Promise.all(
+    transactionIds.map((txId) => waitForTransactionConfirmed(txId, messenger)),


We're waiting for the deposit transactions to succeed, but we also need to poll the Across API to verify the status of their transactions on the target chain.

Looks like /deposit/status?

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

cursor · 2026-02-16T13:44:37Z

packages/transaction-pay-controller/src/strategy/across/across-submit.ts

+    await new Promise((resolve) =>
+      setTimeout(resolve, ACROSS_STATUS_POLL_INTERVAL),
+    );
+  }


Status polling error prevents intent completion after confirmed deposit

Medium Severity

The waitForAcrossCompletion polling loop has no try/catch around successfulFetch or response.json(). A transient network error or malformed response on any single polling attempt causes the entire function to throw. Since submitTransactions calls this at the end, the error propagates up to executeSingleQuote, which skips the isIntentComplete = true update on the parent transaction — even though the on-chain deposit was already confirmed via waitForTransactionConfirmed. This leaves the parent transaction stuck in an incomplete state and surfaces an error to the user for a successfully submitted deposit.

Additional Locations (1)

packages/transaction-pay-controller/src/strategy/across/across-submit.ts#L79-L96

cursor · 2026-02-16T13:44:37Z

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

+  return providerFeeUsd.isNegative()
+    ? new BigNumber(0)
+    : providerFeeUsd;
+}


Fallback provider fee conflates exchange rate with actual fee

Medium Severity

When fees.total.amountUsd is unavailable, calculateProviderUsd computes the provider fee as inputUSD − expectedOutputUSD. The expectedOutputRaw passed in is a fallback-chained value that may be minOutputAmount or targetAmountMinimum instead of the actual expected output. For cross-asset bridges (e.g., ETH → USDC), this delta includes the exchange-rate difference between the two tokens, significantly overstating the actual provider/bridging fee shown to the user.

Additional Locations (1)

packages/transaction-pay-controller/src/strategy/across/across-quotes.ts#L224-L230

cursor

Cursor Bugbot has reviewed your changes and found 2 potential issues.

cursor · 2026-02-16T18:12:19Z

packages/transaction-pay-controller/src/strategy/across/types.ts

+
+export type AcrossActionRequestBody = {
+  actions: AcrossAction[];
+};


Unused exported types for unimplemented delegation feature

Low Severity

AcrossAction, AcrossActionArg, and AcrossActionRequestBody are exported types that are never imported or referenced anywhere in the codebase. A grep confirms zero imports. The PR discussion confirms delegation is not supported yet ("delegation not supported yet, so we can build the actions directly from the transactions"), so these types serve no current purpose and will confuse future developers trying to understand which types are part of the working Across implementation.

cursor · 2026-02-16T18:12:19Z

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

+      usd: '0',
+    },
+  );
+}


Duplicated sumAmounts logic already exists in utilities

Low Severity

The local sumAmounts function in across-quotes.ts duplicates the private sumAmounts in utils/totals.ts. Both reduce an Amount[] by summing fiat, human, raw, and usd fields. Having two independent implementations risks inconsistent bug fixes if the Amount type evolves or a calculation needs correction — one copy could be updated while the other is missed. Extracting the shared logic into a common exported utility would prevent this.

pedronfigueiredo self-assigned this Feb 10, 2026

pedronfigueiredo requested review from a team as code owners February 10, 2026 11:23

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pedronfigueiredo force-pushed the cor-6992-extract-fallback-mechanism branch 4 times, most recently from 9cd0f37 to a6c9af9 Compare February 13, 2026 10:47

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feat(transaction-pay): add Across strategy support

68679f6

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Refine Across strategy behavior and expand coverage

43816bc

pedronfigueiredo force-pushed the cor-6997-across-strategy branch from 0df61f2 to 43816bc Compare February 16, 2026 17:55

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Status polling error prevents intent completion after confirmed deposit

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Fallback provider fee conflates exchange rate with actual fee

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cursor bot Feb 16, 2026

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Unused exported types for unimplemented delegation feature

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Duplicated sumAmounts logic already exists in utilities

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pedronfigueiredo commented Feb 10, 2026 •

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Duplicated `sumAmounts` logic already exists in utilities