feat: Implement `FiatStrategy` submit flow with order polling and relay execution by OGPoyraz · Pull Request #8347 · MetaMask/core

OGPoyraz · 2026-03-31T09:02:39Z

Explanation

Implements FiatStrategy submit flow with order polling and relay execution.

Implement submitFiatQuotes to poll the on-ramp order via RampsController:getOrder until completion, then re-quote and submit the relay leg with the settled crypto amount
Add order validation that verifies the completed order's asset and chain match the expected fiat asset before proceeding with relay
Update relay quote request filtering to support exact-input max amount requests used by the fiat submit re-quote path
Add orderCode field to TransactionFiatPayment and RampsControllerGetOrderAction to AllowedActions to enable order polling from the fiat strategy
Fail-closed on terminal order statuses (failed/cancelled), polling timeout with last-status reporting, asset mismatches, and invalid crypto amounts

References

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
Touches transaction submission flow by adding a new polling + re-quote path and a change to Relay quote filtering, which could affect execution behavior if request classification is incorrect, but it is guarded by strict validation and tests.

Overview
Implements the FiatStrategy submit path: submitFiatQuotes now reads the stored fiat orderId, polls RampsController:getOrder until completion (with timeout and fail-closed terminal statuses), validates the settled order asset/chain, converts the settled crypto amount to a raw source amount, then re-quotes and submits the Relay leg.

Updates Relay quote request filtering to allow exact-input (max-amount) requests used by the fiat re-quote flow, extends messenger AllowedActions to include RampsControllerGetOrderAction, and adds TransactionFiatPayment.orderId to persist the normalized on-ramp order identifier. Adds extensive unit coverage for polling, validation, slippage guardrails, and error cases.

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…ution

OGPoyraz · 2026-03-31T09:07:14Z

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

+  /** Order identifier - `orderCode` specifically used as RampsService:getOrder parameter in normalized format (/providers/{provider}/orders/{id}). */
+  orderCode?: string;


Originally we talked Ramps team to add metadata into fiat orders and also filtering mechanism.
Due to limitation of timeframe this may not be option to deliver besides headless ramp, hence we are adding orderCode (meaning order id) into TransactionFiatPayment

Minor, orderId or rampsId to be more generic?

Done - renamed to orderId

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

OGPoyraz · 2026-03-31T09:16:40Z

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

+      .filter((singleRequest) => {
+        const hasTargetMinimum = singleRequest.targetAmountMinimum !== '0';
+        const isPostQuote = Boolean(singleRequest.isPostQuote);
+        const isExactInputRequest =
+          Boolean(singleRequest.isMaxAmount) &&
+          new BigNumber(singleRequest.sourceTokenAmount).gt(0);
+
+        return hasTargetMinimum || isPostQuote || isExactInputRequest;
+      })


The fiat re-quote request could get dropped by this filter if targetAmountMinimum happened to be '0' - it's not a post-quote, so the second condition wouldn't save it. The isExactInputRequest check distinguishes real exact-input requests (positive source amount + max amount flag) from empty gas fee token requests (zero source amount), ensuring the fiat re-quote passes through.

matthewwalsh0 · 2026-03-31T13:58:35Z

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

+
+const log = createModuleLogger(projectLogger, 'fiat-submit');
+
+const ORDER_POLL_INTERVAL_MS = 1000;


Minor, I added feature flags for this on Relay, could extend for fiat in future.

Good call, I'll extend the feature flags for fiat polling in a follow-up, not only this but also tokens per type.

matthewwalsh0 · 2026-03-31T13:59:04Z

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

+    throw new Error('Missing wallet address for fiat submission');
+  }
+
+  const state = messenger.call('TransactionPayController:getState');


Minor, should this be in the request to make it more "pure"?

Fair point - I can work on this on separate PR as this will touch beyond fiat scope.

matthewwalsh0 · 2026-03-31T14:00:09Z

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

+
+  while (true) {
+    const order = await messenger.call(
+      'RampsController:getOrder',


To clarify, does this trigger a network request in the RampsController?

Would it be more efficient if they owned the polling and we listened to a messenger event like RampsController:quoteStatusChange or RampsController:stateChange if it's updated in state?

Yes it triggers a network request via RampsController:getOrder. Event-based via stateChange would be cleaner - agreed it's the better long-term approach. For now polling keeps fiat self-contained without coupling to RampsController's internal state updates.

In fact this we should be able to just subscribe -order status change-, I will bring this topic once we proceed with other blockers.

matthewwalsh0 · 2026-03-31T14:01:59Z

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

+  const expectedChainId = expectedAssetId.split('/')[0];
+  const orderChainId = orderCrypto?.chainId?.toLowerCase();
+
+  if (orderAssetId && orderAssetId !== expectedAssetId) {


Oh we already have an order ID? Is this generated by the provider or Ramps?

Generated by the provider (e.g Transak). The mobile app receives it after checkout completion and writes it to state via updateFiatPayment. The normalized format /providers/{provider}/orders/{id} is what Ramps uses internally.

So I expect them to execute a callback after successfully checkout passed while starting headless ramps (meaning we have orderId) then regularly fetch in the TPC.

matthewwalsh0 · 2026-03-31T14:02:48Z

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

+    transactionId,
+  });
+
+  const relayQuotes = await getRelayQuotes({


Do we need to validate the final quote to check the fees are within our original slippage compared to what we showed the user?

Or is that a separate PR?

Good catch - added validateRelaySlippage that compares the re-quoted relay's target output against the original. Fails if slippage exceeds 5%.

matthewwalsh0 · 2026-03-31T14:04:00Z

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

+  /** Order identifier - `orderCode` specifically used as RampsService:getOrder parameter in normalized format (/providers/{provider}/orders/{id}). */
+  orderCode?: string;


Minor, orderId or rampsId to be more generic?

cursor

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

cursor · 2026-04-01T08:20:02Z

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

+    isPostQuote: false,
+    sourceBalanceRaw: sourceAmountRaw,
+    sourceTokenAmount: sourceAmountRaw,
+  };


Re-quote may fail when transaction carries contract calldata

Medium Severity

The relay re-quote request sets isPostQuote: false with isMaxAmount: true. Since isPostQuote is false, getSingleQuote calls processTransactions on the original transaction. If that transaction has non-empty, non-token-transfer data (likely for predictDeposit or perpsDeposit contract calls), processTransactions throws "Max amount quotes do not support included transactions." The original fiat quote in fiat-quotes.ts avoids this by using isPostQuote: true to skip processTransactions entirely.

Additional Locations (1)

packages/transaction-pay-controller/src/strategy/relay/relay-quotes.ts#L246-L248

OGPoyraz added 3 commits March 31, 2026 11:01

Implement fiat strategy submit flow with order polling and relay exec…

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…ution

Add changelog

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Merge branch 'main' into ogp/CONF-960

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OGPoyraz marked this pull request as ready for review March 31, 2026 09:04

OGPoyraz requested review from a team as code owners March 31, 2026 09:04

OGPoyraz commented Mar 31, 2026

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

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OGPoyraz commented Mar 31, 2026

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OGPoyraz changed the title ~~feat: Implement fiat strategy submit flow with order polling and relay execution~~ feat: Implement FiatStrategy submit flow with order polling and relay execution Mar 31, 2026

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OGPoyraz mentioned this pull request Mar 31, 2026

feat: Add fiat payment confirmation flow with headless ramp integration placeholder MetaMask/metamask-mobile#28152

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vinistevam previously approved these changes Mar 31, 2026

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matthewwalsh0 requested changes Mar 31, 2026

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OGPoyraz dismissed vinistevam’s stale review via 3362eff April 1, 2026 08:13

OGPoyraz requested a review from matthewwalsh0 April 1, 2026 08:15

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OGPoyraz added 2 commits April 1, 2026 10:59

Update

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Fix lint

6cd9e68

		/** Order identifier - `orderCode` specifically used as RampsService:getOrder parameter in normalized format (/providers/{provider}/orders/{id}). */
		orderCode?: string;


		const log = createModuleLogger(projectLogger, 'fiat-submit');

		const ORDER_POLL_INTERVAL_MS = 1000;

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Re-quote may fail when transaction carries contract calldata

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OGPoyraz commented Mar 31, 2026 •

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