feat(rewards): update mUSD calculator tab with slider and revamped design

[andrewjcohen]

Description

This PR replaces the placeholder mUSD Rewards tab with a calculator-style experience so users can explore estimated earnings from holding mUSD.

The tab now shows a hero (hold / earn messaging), an amount slider with labeled scale points ($100–$10,000), estimated yearly / monthly / daily earnings derived from a fixed APY constant, disclaimer copy, and primary CTAs (buy / swap). Slider mapping, snapping, and clamping live in pure helpers (musdCalculatorSlider) with unit tests. Strings are added under rewards.musd.* across supported locales.

Changelog

CHANGELOG entry: Updated the mUSD bonus calculator in Rewards with a fresh design.

Related issues

No issue: Rewards mUSD calculator UI iteration (no GitHub or Jira ticket linked).

Manual testing steps

Feature: Rewards mUSD calculator tab

  Scenario: User views calculator and adjusts amount
    Given the user opens MetaMask Mobile and navigates to Rewards
    When the user selects the mUSD calculator tab (or equivalent entry for mUSD)
    Then the calculator hero, amount slider, estimated earnings, disclaimer, and CTAs are visible

  Scenario: User moves the slider
    Given the mUSD calculator tab is open
    When the user drags the amount slider across the track
    Then the displayed amount and estimated earnings update consistently and remain within the expected min/max range

Screenshots/Recordings

Before

N/A

After

N/A

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I've included tests if applicable
• I've documented my code using JSDoc format if applicable
• I've applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Performance checks (if applicable)

• I've tested on Android
  • Ideally on a mid-range device; emulator is acceptable
• I've tested with a power user scenario
  • Use these power-user SRPs to import wallets with many accounts and tokens
• I've instrumented key operations with Sentry traces for production performance metrics
  • See trace() for usage and addToken for an example

For performance guidelines and tooling, see the Performance Guide.

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.

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Note

Medium Risk
Medium risk due to a substantial UI rewrite introducing custom gesture-driven slider behavior (Reanimated/Gesture Handler) and new i18n keys, which could affect interaction/formatting and non-English copy if translations are incomplete.

Overview
Replaces the Rewards mUSD calculator tab UI with a new slider-driven experience: a redesigned hero/earnings display, editable amount input, and a custom press/drag slider (with snapping/clamping) that updates estimated daily/yearly earnings.

Adds pure slider mapping helpers in musdCalculatorSlider (with unit tests), updates button wiring/testIDs and interaction tests (press, pan gestures, input normalization), and wraps MusdCalculatorView content in a KeyboardAvoidingView with a new test.

Updates rewards.musd.* strings (new English copy/keys) and removes the prior localized string set in many non-English locale files.

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[github-actions]

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[andrewjcohen]

I have read the CLA Document and I hereby sign the CLA

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: None (no tests recommended)
• Selected Performance tags: None (no tests recommended)
• Risk Level: low
• AI Confidence: 90%

click to see 🤖 AI reasoning details

E2E Test Selection:
The changes are entirely contained within the Rewards feature's mUSD calculator:

1. MusdCalculatorView.tsx / MusdCalculatorTab.tsx: New/redesigned UI components for the mUSD earnings calculator within the Rewards section. These are registered as a screen in RewardsNavigator under Routes.REWARDS_MUSD_CALCULATOR_VIEW. They don't modify any shared infrastructure.

2. musdCalculatorSlider.ts: Pure utility functions (amount↔percent conversion, snapping, clamping) with no side effects on other features.

3. Locale files: Updated rewards.musd.* string keys across 21 languages. The changes are additive/renaming within the rewards.musd namespace only — no other locale keys are affected.

No E2E tests exist for the Rewards/mUSD calculator feature — a thorough search of the tests/ directory found no test files referencing rewards, mUSD, or the calculator. The Rewards feature is not covered by any of the available E2E test tags.

No shared components are modified: TabBar, navigation primitives, modals, confirmations, controllers, and Engine are all untouched. The swap button in MusdCalculatorTab uses useSwapBridgeNavigation for navigation only — it doesn't modify the swap flow itself.

Risk is low: These are isolated UI changes to a feature with no existing E2E coverage. Running any test suite would not validate these changes, and the changes cannot break existing tests since no shared infrastructure is modified.

Performance Test Selection:
The changes are limited to a Rewards feature UI component (mUSD calculator slider and view) and locale string updates. These are isolated UI components with no impact on app startup, account/network list rendering, login flows, or other performance-sensitive paths. No performance tests are warranted.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
96.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud