feat(peprs): dynamic fee calculation

[abretonc7s]

Description

Fixed incorrect hardcoded fee display in HyperLiquid trading by implementing dynamic fee calculation that reflects user-specific discounts and fee tiers.

Problem:
HyperLiquid fees were hardcoded at 0.045% for both market and limit orders, causing incorrect fee estimates for users. This didn't account for:

• Different maker/taker rates (market vs limit orders)
• Volume-based fee tiers (0-6 tiers based on 14-day volume)
• Referral code discounts (up to 40%)
• HYPE token staking discounts (5-40% based on tier)

Solution:
Updated the calculateFees method in HyperLiquidProvider.ts to:

1. Use correct API fields: Changed from deprecated userFees.feeSchedule.* to userFees.userCrossRate/userAddRate
2. Apply discounts manually: HyperLiquid API returns base rates, so we manually apply referral + staking discounts (capped at 40%)
3. Enhanced logging: Added comprehensive DevLogger statements for debugging fee calculations
4. Better validation: Added fee rate validation before caching

This now provides accurate fee estimates that match what users see in the HyperLiquid UI.

Changelog

CHANGELOG entry: Fixed HyperLiquid fee calculation to show dynamic rates instead of hardcoded 0.045%

Related issues

Fixes: TAT-1440

Manual testing steps

Feature: Dynamic HyperLiquid Fee Calculation

  Scenario: User with no discounts sees base rates
    Given user has no referral code set
    And user has no HYPE staked
    When user views market order fee estimate
    Then fee should show base taker rate (0.045%)
    When user views limit order fee estimate  
    Then fee should show base maker rate (0.015%)

  Scenario: User with referral discount sees reduced rates
    Given user has MetaMask referral code set
    When user views order fee estimate
    Then fee should show reduced rate based on referral discount
    And discount should be visible in logs

  Scenario: User with HYPE staking sees additional discounts
    Given user has HYPE tokens staked
    When user views order fee estimate
    Then fee should show combined referral + staking discounts
    But total discount should not exceed 40%

  Scenario: High volume trader sees better rates
    Given user has high 14-day trading volume
    When user views order fee estimate
    Then fee should show volume-tier based rates
    And rates should be lower than base rates

  Scenario: API error fallback works correctly
    Given HyperLiquid API is unavailable
    When user views order fee estimate
    Then fee should fallback to base rates (0.045%/0.015%)
    And error should be logged but not shown to user

Screenshots/Recordings

Before

• All orders showed hardcoded 0.045% HyperLiquid fee regardless of order type or user discounts
• No consideration for referral codes or staking rewards
• Inaccurate fee estimates compared to actual HyperLiquid UI

After

• Market orders show dynamic taker rates (e.g., 0.0432% with MetaMask referral)
• Limit orders show dynamic maker rates (e.g., 0.0144% with MetaMask referral)
• Fees accurately reflect user's volume tier, referral discounts, and staking rewards
• Fee estimates match HyperLiquid UI calculations
• Comprehensive logging for debugging fee calculations

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.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
89.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud