feat: Implement `FiatStrategy` and `getQuotes` functionality by OGPoyraz · Pull Request #8121 · MetaMask/core

OGPoyraz · 2026-03-05T14:56:30Z

Explanation

This PR introduces FiatStrategy:

Adds TransactionPayStrategy.Fiat and registers FiatStrategy in strategy resolution.
Adds Fiat asset mapping by tx type in constants (MMPAY_FIAT_ASSET_ID_BY_TX_TYPE).
Implements Fiat quote flow in fiat-quotes.ts with relay-first estimation:
- reads fiatPayment.amountFiat + selected payment method
- estimates relay fees first
- requests ramps quotes with adjusted fiat amount
- returns one combined strategy: fiat quote
Splits fees in the combined quote:
- fees.provider = relay provider/swap fee
- fees.fiatProvider = ramps provider/network fee
- fees.metaMask = MM fee (100 bps over amountFiat + adjustedAmountFiat)
Updates totals/metadata sync so fee aggregation stays consistent, including combined metamaskPay.bridgeFeeFiat when fiat provider fee exists.
Adds package wiring for ramps types/dependency and updates changelog.

References

Fixes https://github.com/MetaMask/MetaMask-planning/issues/7069

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
Adds a new Fiat payment strategy that combines Relay fee estimation with Ramps quote retrieval and introduces a new fee bucket (fees.fiatProvider), which can affect totals and transaction metadata calculations.

Overview
Adds a new MM Pay FiatStrategy and wiring (TransactionPayStrategy.Fiat) to generate quotes by first estimating fees via Relay, then requesting Ramps quotes using an adjusted fiat amount (user amount + estimated relay fees), returning a single combined quote.

Introduces TransactionPayFiatAsset + tx-type-to-fiat-asset mapping, adds RampsController:getQuotes to messenger AllowedActions, and updates fee/totals plumbing to support a separate fees.fiatProvider bucket (including aggregating it into totals and metamaskPay.bridgeFeeFiat).

Includes new unit tests for the fiat quote flow/utilities and adds @metamask/ramps-controller dependency/build references; fiat execute is currently a placeholder returning no tx hash.

^{Written by Cursor Bugbot for commit ee58873. This will update automatically on new commits. Configure here.}

socket-security · 2026-03-05T14:58:34Z

No dependency changes detected. Learn more about Socket for GitHub.

👍 No dependency changes detected in pull request

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

OGPoyraz · 2026-03-17T10:16:52Z

@SocketSecurity ignore npm/@metamask/ramps-controller@12.0.0

cursor

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

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cursor · 2026-03-17T10:23:33Z

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

+      amount: adjustedAmount,
+      paymentMethods: [selectedPaymentMethodId],
+      walletAddress,
+    });


Missing assetId in ramps getQuotes call

High Severity

The RampsController:getQuotes call is missing the assetId parameter. The fiatAsset object (derived from deriveFiatAssetForFiatPayment) contains a caipAssetId field that was clearly intended to be passed as assetId, but it's never included in the call. The RampsController.getQuotes method validates that assetId is present and throws "assetId is required." if neither the parameter nor this.state.tokens.selected?.assetId is available. This causes the fiat quote flow to either silently fail (caught by try-catch, returning []) or use an unrelated asset from ramps controller state.

Additional Locations (1)

packages/transaction-pay-controller/src/constants.ts#L17-L23

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

matthewwalsh0 · 2026-03-20T21:57:35Z

packages/transaction-pay-controller/CHANGELOG.md

 ### Added

 - **BREAKING:** Add `AssetsControllerGetStateForTransactionPayAction` to the `AllowedActions` messenger type ([#8163](https://github.com/MetaMask/core/pull/8163))
+- Add MMPay `FiatStrategy` quotes flow ([#8121](https://github.com/MetaMask/core/pull/8121))


Suggested change

- Add MMPay `FiatStrategy` quotes flow ([#8121](https://github.com/MetaMask/core/pull/8121))

- Add `FiatStrategy` to retrieve quotes via `RampsController` ([#8121](https://github.com/MetaMask/core/pull/8121))

matthewwalsh0 · 2026-03-20T21:58:18Z

packages/transaction-pay-controller/src/constants.ts

 export const POLYGON_USDCE_ADDRESS =
  '0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174' as Hex;

+export type TransactionPayFiatAsset = {


Should all of the be in strategy/fiat/[types|consants].ts?

matthewwalsh0 · 2026-03-20T22:00:48Z

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

+
+import type { RelayQuote } from '../relay/types';
+
+export type FiatOriginalQuote = {


Minor, in the context of this controller, could this just be FiatQuote?

matthewwalsh0 · 2026-03-20T22:01:24Z

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

+import type { RelayQuote } from '../relay/types';
+
+export type FiatOriginalQuote = {
+  fiatQuote: Quote;


Would it add clarity to call this rampsQuote as "Fiat" is our abstraction over Ramps and Relay together?

matthewwalsh0 · 2026-03-20T22:03:04Z

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

  provider: FiatValue;

+  /** Fee charged by fiat on-ramp provider. */
+  fiatProvider?: FiatValue;


providerFiat?

Or should we be more generic and call this providerSecondary so we can have a mechanism to have a more granular fee and the client can choose what to call it?

matthewwalsh0 · 2026-03-20T22:22:09Z

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

+
+function getRampsProviderFee(fiatQuote: RampsQuote): BigNumber {
+  return new BigNumber(fiatQuote.quote.providerFee ?? 0).plus(
+    fiatQuote.quote.networkFee ?? 0,


Nice, so they obviously handle any network fees, but include it separately?

matthewwalsh0 · 2026-03-20T22:23:16Z

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

+        fiat: metaMaskFee,
+        usd: metaMaskFee,
+      },
+      provider: relayQuote.fees.provider,


For consistency, this needs to be the total provider fee for the quote, so ramps + relay.

Meaning we can calculate the Relay portion if needed in the client by subtracting the fiatProvider value.

matthewwalsh0 · 2026-03-20T22:23:57Z

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

+    }
+  }
+
+  return MMPAY_FIAT_ASSET_ID_BY_TX_TYPE[transactionType as TransactionType];


Minor, is MMPAY implied?

matthewwalsh0 · 2026-03-20T22:24:38Z

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

      tx.metamaskPay = {
-        bridgeFeeFiat: totals.fees.provider.usd,
+        bridgeFeeFiat: totals.fees.fiatProvider
+          ? new BigNumber(totals.fees.provider.usd)


As mentioned in other comment, this shouldn't be needed as provider always needs to be the total.

matthewwalsh0 · 2026-03-20T22:25:09Z

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

    .toString(10);

  const totalUsd = new BigNumber(providerFee.usd)
+    .plus(fiatProviderFee.usd)


Also here, this is an additional optional breakdown, but provider remains the total provider fee.

OGPoyraz requested review from a team as code owners March 5, 2026 14:56

OGPoyraz force-pushed the ogp/7069 branch from a6dd26b to 23e8bab Compare March 5, 2026 14:57

OGPoyraz added the DO-NOT-MERGE label Mar 5, 2026

OGPoyraz changed the title ~~feat: Implement FiatStrategy and getQuotes functionality~~ [DONT MERGE] feat: Implement FiatStrategy and getQuotes functionality Mar 5, 2026

cursor bot reviewed Mar 5, 2026

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packages/transaction-pay-controller/src/strategy/fiat/fiat-quotes.ts Show resolved Hide resolved

OGPoyraz commented Mar 9, 2026

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packages/transaction-pay-controller/src/strategy/fiat/fiat-quotes.ts Show resolved Hide resolved

Implement FiatStrategy and getQuotes functionality

266a525

OGPoyraz force-pushed the ogp/7069 branch from 23e8bab to 266a525 Compare March 17, 2026 10:14

OGPoyraz changed the title ~~[DONT MERGE] feat: Implement FiatStrategy and getQuotes functionality~~ feat: Implement FiatStrategy and getQuotes functionality Mar 17, 2026

OGPoyraz removed the DO-NOT-MERGE label Mar 17, 2026

Update yarnlock

c532265

cursor bot reviewed Mar 17, 2026

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Fix lint

ee58873

matthewwalsh0 requested changes Mar 20, 2026

View reviewed changes

	- Add MMPay `FiatStrategy` quotes flow ([#8121](https://github.com/MetaMask/core/pull/8121))
	- Add `FiatStrategy` to retrieve quotes via `RampsController` ([#8121](https://github.com/MetaMask/core/pull/8121))


		import type { RelayQuote } from '../relay/types';

		export type FiatOriginalQuote = {

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Missing assetId in ramps getQuotes call

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OGPoyraz commented Mar 5, 2026 •

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Missing `assetId` in ramps `getQuotes` call

matthewwalsh0 Mar 20, 2026 •

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