Mizupay: Sui BTC PayFi Protocol

Mizupay is a DeFi protocol built on Sui that enables users to:

1. Deposit LBTC as collateral to mint mzUSD stablecoins
2. Stake mzUSD tokens to receive smzUSD which is yield-bearing stablecoin
3. Use the yield to claim USDC upfront and use in payment

Protocol Overview

Vault Program

The vault program allows users to:

• Deposit LBTC as collateral and mint mzUSD stablecoins at a 70% loan-to-value ratio
• Repay mzUSD to unlock and withdraw their LBTC collateral
• Maintain over-collateralization to prevent liquidation

Staking Program

The staking program enables users to:

• Stake mzUSD tokens and receive smzUSD tokens 1:1
• Unstake by burning smzUSD tokens to receive back their mzUSD

Client Application

A web-based interface for interacting with the protocol, built with:

• TypeScript
• Vite
• React
• Sui Wallet Kit

Getting Started

Prerequisites

• Sui CLI tools
• Node.js 16+
• pnpm package manager

Setup

# Clone the repository
git clone https://github.com/yourusername/Mizupay.git
cd Mizupay

# Build Sui modules (once the Sui contracts are ready)
# cd program/modules
# sui move build

# Set up the client application
cd client
pnpm install
pnpm dev

Usage

Minting mzUSD

1. Connect your wallet through the client interface
2. Navigate to the Mint section
3. Deposit LBTC as collateral
4. Mint mzUSD tokens (up to 70% of your collateral value)

Staking mzUSD

1. Navigate to the Earn section
2. Approve mzUSD for staking
3. Stake your mzUSD to receive smzUSD tokens
4. Unstake anytime by burning smzUSD tokens

Architecture

Smart Contracts

• Sui Move modules for vault and staking functionality

Price Oracle (Pyth)

Mizupay integrates Pyth Network to fetch the on-chain BTC/USD price that secures the protocol's LTV calculations.

• On every deposit & borrow action the client app

  1. Queries the Hermes service for the latest BTC/USD price-feed update.
  2. Injects that update into the same transaction via SuiPythClient.updatePriceFeeds, obtaining a fresh PriceInfoObject id.
  3. Passes the returned PriceInfoObject to the lending::borrow Move entry-function, ensuring all collateral checks rely on the most up-to-date oracle data.

• The Move module lending.move uses the supplied PriceInfoObject (and a time-stamp-verified Clock) to

  • calculate max_borrowable and max_withdrawable,
  • validate collateral ratios,
  • and remain oracle-agnostic (any asset supported by Pyth can be added in the future).

This design removes any need for off-chain price pushers—the oracle update and user operation are executed atomically in a single transaction.

Client

The client application provides a user-friendly interface to interact with the Sui modules, handling:

• Wallet connections via Sui Wallet Kit
• Transaction building and signing
• Real-time updates of user positions
• Responsive UI for both desktop and mobile devices

Development

Client Development

cd client
pnpm dev       # Start development server on port 8080
pnpm build     # Build for production
pnpm preview   # Preview production build

Features

• Dashboard: View your assets, accumulated yield, and staked mzUSD management
• Deposit: Convert BTC to LBTC
• Mint: Lock LBTC and mint mzUSD
• Earn: Stake mzUSD to earn yield with smzUSD

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