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 quoting path that combines relay fee estimation with fiat on-ramp quotes and introduces new fee breakdown fields, which could affect quote selection and totals calculations. Risk is moderated by extensive unit tests and the submit path being a placeholder.

Overview
Adds a new TransactionPayStrategy.Fiat and registers FiatStrategy, enabling MM Pay to return combined fiat+relay quotes by first estimating relay fees, then requesting RampsController:getQuotes with an adjusted fiat amount.

Extends the quote/totals data model to carry fiatPaymentMethod through quoting and to include an optional fees.providerFiat breakdown (fiat on-ramp provider/network fees), and updates totals aggregation and metadata sync logic accordingly.

Wires in @metamask/ramps-controller (deps + TS references), adds fiat-asset mappings by transaction type, introduces computeRawFromFiatAmount, and includes comprehensive tests for the new fiat quote flow and edge cases.

^{Written by Cursor Bugbot for commit ee9b3b7. 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

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

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?

Moved to strategy/fiat/constants.ts and strategy/fiat/utils.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?

Renamed to 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?

Good call, renamed to rampsQuote

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?

Went with providerFiat for now, we can generalize later if needed

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?

Exactly, not sure how accurate that is but it's definitely in the quote as I saw from testing.

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.

fees.provider is now relay + ramps combined; providerFiat is the ramps-only breakdown.

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?

Done, renamed to FIAT_ASSET_ID_BY_TX_TYPE

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.

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cursor · 2026-03-22T21:06:22Z

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

+    // TODO: Implement provider selection logic; force Transak staging for now.
+    (quote) => quote.provider === '/providers/transak-native-staging',
+  );
+}


Hardcoded staging provider blocks production fiat quotes

Medium Severity

pickBestFiatQuote only matches the staging provider string '/providers/transak-native-staging'. In any non-staging environment the ramps response will use a different provider identifier, causing this function to always return undefined and the fiat strategy to produce no quotes.

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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OGPoyraz commented Mar 9, 2026

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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

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Fix lint

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matthewwalsh0 requested changes Mar 20, 2026

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OGPoyraz added 2 commits March 22, 2026 21:42

Address comments

a7204d9

Merge branch 'main' into ogp/7069

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OGPoyraz requested a review from matthewwalsh0 March 22, 2026 20:43

Fix lint and changelog

ee9b3b7

cursor bot reviewed Mar 22, 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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Hardcoded staging provider blocks production fiat quotes

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OGPoyraz commented Mar 5, 2026 •

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