fix: update non-evm token balances on flip

[GeorgeGkas]

Description

fixes an issue where flipping source/dest assets do not update balances when user has zero balance on non-evm chains

Changelog

CHANGELOG entry: fixes an issue where flipping source/dest assets do not update balances when user has zero balance on non-evm chains

Related issues

Fixes: https://consensyssoftware.atlassian.net/browse/SWAPS-3693

Manual testing steps

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

Before

After

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.

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.

---

Note

Improves useLatestBalance behavior for non‑EVM and token switching scenarios.

• Resets balance state when token.address changes to avoid stale UI; returns cached balance immediately while fetching new data
• For non‑EVM chains, uses controller data and sets balance to 0 when token not found or balance is empty/undefined
• Expands effect deps to include previous/current token address
• Adds comprehensive tests covering address flips, non‑EVM fallbacks, zero/invalid balances, and race conditions

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🔍 Smart E2E Test Selection

• Selected E2E tags: SmokeTrade, SmokeSwaps
• Risk Level: medium
• AI Confidence: 85%

click to see 🤖 AI reasoning details

The changes are focused on the useLatestBalance hook in the Bridge component, which is used for displaying token balances during bridge/swap operations. The modifications include:

1. Bug fix for stale balance display: Added logic to reset balance state when token address changes, preventing stale balance from being shown when switching tokens.

2. Bug fix for non-EVM tokens: Added handling for when non-EVM tokens are not found in the balance controller, setting balance to 0 instead of leaving it undefined/stale.

3. Comprehensive unit tests: Added extensive test coverage for the new edge cases.

The hook is used in:

• BridgeView - Main bridge view component
• QuoteDetailsCard - Quote details display
• SwapsKeypad - Swap input keypad
• useBridgeQuoteRequest - Bridge quote request hook

These are all part of the Bridge/Swap functionality, making SmokeTrade (which covers token swaps, bridge, DEX trading) and SmokeSwaps (token swap functionality) the appropriate test tags. The changes are well-contained bug fixes with good test coverage, representing medium risk as they affect user-facing balance display in trading flows.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud