feat: add metrics property mm_pay_time_to_complete_s (#27476)

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## **Description**

Add new property for MM Pay transaction metrics
`mm_pay_time_to_complete_s`. Which is time from when transaction is
submitted to what it is finalized.

## **Changelog**

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CHANGELOG entry:

## **Related issues**

Fixes: https://consensyssoftware.atlassian.net/browse/CONF-721

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

## **Screenshots/Recordings**
NA

## **Pre-merge author checklist**

- [X] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [X] I've completed the PR template to the best of my ability
- [X] I've included tests if applicable
- [X] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [X] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk analytics-only change that adds a derived timing property on
`TRANSACTION_FINALIZED` events; main risk is incorrect/undefined
`submittedTime` leading to missing or skewed metrics.
> 
> **Overview**
> Adds a new MetaMetrics property, `mm_pay_time_to_complete_s`, to
MetaMask Pay transaction metrics, computed as seconds from
`submittedTime` to `TRANSACTION_FINALIZED`.
> 
> The metric is emitted for both parent pay transactions and child
bridge/swap steps (using the parent transaction’s `submittedTime`), with
unit tests covering finalized vs non-finalized events and missing
timestamps.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
b3f5da6. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: jpuri

app/core/Engine/controllers/transaction-controller/metrics_properties/metamask-pay.test.ts

@@ -484,4 +484,75 @@ describe('Metamask Pay Metrics', () => {
       sensitiveProperties: {},
     });
   });
+
+  describe('mm_pay_time_to_complete_s', () => {
+    afterEach(() => {
+      jest.restoreAllMocks();
+    });
+
+    it('adds mm_pay_time_to_complete_s for finalized parent MM Pay transaction', () => {
+      jest.spyOn(Date, 'now').mockReturnValue(1060500);
+
+      request.transactionMeta.type = TransactionType.perpsDeposit;
+      request.transactionMeta.submittedTime = 1000000;
+
+      const result = getMetaMaskPayProperties(request) as TransactionMetrics;
+
+      expect(result.properties).toStrictEqual(
+        expect.objectContaining({
+          mm_pay_time_to_complete_s: 60.5,
+        }),
+      );
+    });
+
+    it('adds mm_pay_time_to_complete_s for finalized child transaction using parent submittedTime', () => {
+      jest.spyOn(Date, 'now').mockReturnValue(2045123);
+
+      request.allTransactions = [
+        {
+          id: 'parent-1',
+          type: TransactionType.perpsDeposit,
+          requiredTransactionIds: ['child-1'],
+          submittedTime: 2000000,
+        } as TransactionMeta,
+      ];
+
+      const result = getMetaMaskPayProperties(request) as TransactionMetrics;
+
+      expect(result.properties).toStrictEqual(
+        expect.objectContaining({
+          mm_pay_time_to_complete_s: 45.123,
+        }),
+      );
+    });
+
+    it('does not add mm_pay_time_to_complete_s for non-finalized events', () => {
+      request.eventType = TRANSACTION_EVENTS.TRANSACTION_SUBMITTED;
+      request.transactionMeta.type = TransactionType.perpsDeposit;
+      request.transactionMeta.submittedTime = 1000000;
+
+      const result = getMetaMaskPayProperties(request) as TransactionMetrics;
+
+      expect(result.properties).not.toHaveProperty('mm_pay_time_to_complete_s');
+    });
+
+    it('does not add mm_pay_time_to_complete_s when submittedTime is undefined', () => {
+      request.transactionMeta.type = TransactionType.perpsDeposit;
+
+      const result = getMetaMaskPayProperties(request) as TransactionMetrics;
+
+      expect(result.properties).not.toHaveProperty('mm_pay_time_to_complete_s');
+    });
+
+    it('does not add mm_pay_time_to_complete_s for non-MM-Pay transactions', () => {
+      jest.spyOn(Date, 'now').mockReturnValue(1060000);
+
+      request.transactionMeta.type = TransactionType.contractInteraction;
+      request.transactionMeta.submittedTime = 1000000;
+
+      const result = getMetaMaskPayProperties(request) as TransactionMetrics;
+
+      expect(result.properties).not.toHaveProperty('mm_pay_time_to_complete_s');
+    });
+  });
 });

app/core/Engine/controllers/transaction-controller/metrics_properties/metamask-pay.ts

@@ -15,6 +15,7 @@ import {
 import { RootState } from '../../../../../reducers';
 import { selectSingleTokenByAddressAndChainId } from '../../../../../selectors/tokensController';
 import { Hex } from '@metamask/utils';
+import { TRANSACTION_EVENTS } from '../../../../Analytics/events/confirmations';
 
 const FOUR_BYTE_SAFE_PROXY_CREATE = '0xa1884d2c';
 
@@ -34,6 +35,7 @@ const PAY_TYPES = [
 ];
 
 export const getMetaMaskPayProperties: TransactionMetricsBuilder = ({
+  eventType,
   transactionMeta,
   allTransactions,
   getUIMetrics,
@@ -58,6 +60,10 @@ export const getMetaMaskPayProperties: TransactionMetricsBuilder = ({
   if (hasTransactionType(transactionMeta, PAY_TYPES) || !parentTransaction) {
     addFallbackProperties(properties, transactionMeta, getState());
 
+    if (hasTransactionType(transactionMeta, PAY_TYPES) || properties.mm_pay) {
+      addTimeToComplete(properties, eventType, transactionMeta.submittedTime);
+    }
+
     return {
       properties,
       sensitiveProperties,
@@ -127,12 +133,30 @@ export const getMetaMaskPayProperties: TransactionMetricsBuilder = ({
     }
   }
 
+  addTimeToComplete(properties, eventType, parentTransaction.submittedTime);
+
   return {
     properties,
     sensitiveProperties,
   };
 };
 
+function addTimeToComplete(
+  properties: JsonMap,
+  eventType: Parameters<TransactionMetricsBuilder>[0]['eventType'],
+  submittedTime: number | undefined,
+) {
+  if (
+    eventType !== TRANSACTION_EVENTS.TRANSACTION_FINALIZED ||
+    typeof submittedTime !== 'number'
+  ) {
+    return;
+  }
+
+  properties.mm_pay_time_to_complete_s =
+    Math.round(Date.now() - submittedTime) / 1000;
+}
+
 function addFallbackProperties(
   properties: JsonMap,
   transaction: TransactionMeta,