Add n.exchange centralized swap integration

[MMrj9]

Add n.exchange centralized swap integration

Description

Integrate n.exchange as a centralized swap provider supporting multiple networks and tokens. The implementation uses contract addresses for token identification, eliminating the need for currency code mapping. This approach provides better support for tokens and aligns with API requirements.

The integration includes support for native currencies and ERC20 tokens across major networks including Ethereum, Polygon, Base, Arbitrum, Optimism, BSC, and others. The plugin handles rate queries, order creation, and payment processing through the n.exchange API v2.

Additional changes include mapctl tooling for automatic provider mappings and updates to existing swap plugins to use the new mapping system.

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes
• No

Dependencies

none

Changes

• Add n.exchange centralized swap plugin implementation
• Support for contract address-based token identification
• Integration with n.exchange API v2 for rate queries and order management
• Support for multiple networks: Ethereum, Polygon, Base, Arbitrum, Optimism, BSC, and others
• Mapctl tooling for automatic provider mappings
• Updates to existing swap plugins to use new mapping system

Testing

• Unit tests added/updated (nexchange tests included in partnerJson.test.ts)
• Manual testing completed

Checklist

• Code follows project style guidelines
• Commit message follows git commit guidelines
• Branch is synced with upstream master
• Tests pass locally (26 passing)
• Documentation updated (CHANGELOG.md updated)
• Linting passes
• Type checking passes (nexchange-specific types fixed)

---

Note

Adds a new centralized swap provider with contract address-based token support and API v2 rate/order flows.

• New swap/central/nexchange.ts plugin (pluginId: nexchange) using contract-address formatting, mainnet code transcription, min/max checks, and fixed-rate order creation
• Registered nexchange in src/index.ts
• Added partner mapping test/partnerJson/nexchangeMap.json and tests in test/partnerJson/partnerJson.test.ts
• Test config updated with NEXCHANGE_INIT in test/testconfig.ts
• CHANGELOG entry under Unreleased

^{Written by Cursor Bugbot for commit 1166816. This will update automatically on new commits. Configure here.}

[cursor]

Promo code parameter silently ignored in swap

Medium Severity

The opts parameter containing promoCode is declared in fetchSwapQuote but is never used anywhere in the plugin. Other swap plugins like changenow and godex extract and pass this parameter to their respective APIs. In nexchange, if a user provides a promo code expecting a discount or special rate, it gets silently ignored. The promo code is not passed to getFixedQuote or included in the order body sent to the n.exchange API.

 

[MMrj9]

promoCode support can be added at some point