Nexus Vault

Production-grade upgradeable smart contract vault for the Avail Nexus cross-chain intent settlement protocol.

Overview

Nexus Vault enables secure handling of cross-chain intents with support for ERC20 tokens and native assets across multiple blockchain ecosystems (Ethereum, Fuel, Solana, Tron). The vault uses an intent-based architecture where users sign messages off-chain and relayers execute transactions on their behalf.

Architecture

Core Components

• Vault.sol - Main upgradeable contract handling deposits, fulfillments, and settlements

Key Features

• Intent-Based Execution: Users sign intents off-chain; relayers execute on-chain
• Gasless User Experience: Users only pay gas once for token approvals
• Cross-Chain Support: Handles intents across Ethereum, Fuel, Solana, and Tron
• Signature Verification: EIP-191 compliant message signing
• Reentrancy Protection: Transient reentrancy guards for gas efficiency
• Access Control: Role-based permissions for upgrades and settlements

Request Flow

1. Deposit - User signs intent, relayer deposits funds into vault
2. Fulfillment - Solver fulfills the intent on destination chain
3. Settlement - Avail blockchain multisig settles payments to solvers

Usage

Prerequisites

node >= 18.0.0
npm >= 9.0.0

Installation

npm install

Testing

# Run full test suite
npx hardhat test

# Run tests with coverage
npx hardhat coverage

# Run tests on local network
npm run test:local

Deployment

# Compile contracts
npm run compile

# Deploy to multiple networks
npm run deploy:multi

# Upgrade existing proxies
npm run upgrade:multi

# Estimate gas costs
npm run estimate-gas

Contract Addresses

Mainnet and testnet addresses to be added post-deployment

Security

• Audits: Contracts are designed following OpenZeppelin best practices
• Upgradeability: UUPS proxy pattern with role-based upgrade authorization
• Reentrancy: Transient reentrancy guards protect all state-changing functions
• Signature Replay Protection: Nonce-based replay protection for all operations

Access Control Roles

• DEFAULT_ADMIN_ROLE - Contract administration
• UPGRADER_ROLE - Contract upgrade authorization
• SETTLEMENT_VERIFIER_ROLE - Settlement signature verification

Dependencies

• @openzeppelin/contracts ^5.5.0
• @openzeppelin/contracts-upgradeable ^5.5.0
• hardhat ^2.28.0

License

MIT License - see individual contract files for SPDX identifiers.

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