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## **Description**

This PR adds a segment event to track when the Market Insights card
comes into view. This is necessary because at the moment it always
renders below the fold, making it arduous to get good CTR data for the
Market Insights feature. This adds a useful, intermediate step in the
funnel.


https://github.com/user-attachments/assets/f6267a60-300d-4aaf-831e-970af5f43743




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## **Changelog**

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CHANGELOG entry: null

## **Related issues**

Fixes:

## **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**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

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### **After**

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## **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]
> **Medium Risk**
> Adds a new visibility-detection hook that uses a 250ms polling
interval until the card is visible, which could impact performance or
battery if misapplied. Other changes are additive analytics property
updates with low functional risk.
> 
> **Overview**
> Adds a new `MARKET_INSIGHTS_CARD_SCROLLED_TO_VIEW` analytics event
that fires once when the Market Insights entry card becomes at least 50%
visible, using a new `useViewportTracking` hook (layout + short polling)
and wiring it into `MarketInsightsEntryCard`.
> 
> Extends Market Insights telemetry to include `asset_symbol` on
`MARKET_INSIGHTS_OPENED`, `MARKET_INSIGHTS_VIEWED`, and
`MARKET_INSIGHTS_INTERACTION` events (token + perps contexts), with
updated unit tests to assert the new properties and event emission.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
4407c73. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->