MicroStack

Overview

This repository builds a modular microlending platform for the Stellar Soroban smart contract stack. Microlending introduces the risk of default, so the contracts are designed to handle collateral, interest accrual, and liquidations without a single monolithic contract.

Core contracts

The system is composed of small, focused contracts that interact with each other:

1. Lending Pool Contract (The Core)

   • Accepts USDC deposits from lenders and allows borrowers to withdraw loans from pooled liquidity.
   • Mints pool shares (e.g., lUSDC) to represent a lender’s proportional ownership of the pool plus accrued interest.
   • Records borrower loans with principal, start timestamp, duration, and interest rate.
   • Contract: contracts/lending_pool/src/lib.rs

2. Collateral & Liquidation Contract (The Enforcer)

   • Escrows collateral (e.g., XLM or another SEP-41 asset) on behalf of the borrower.
   • Tracks collateral health and allows liquidations if collateral value falls below a safe threshold or loan duration expires.
   • Enables liquidators to repay debt in exchange for collateral at a discount.
   • Contract: contracts/collateral_liquidation/src/lib.rs

3. Interest Rate Strategy Contract (The Calculator)

   • Calculates dynamic interest rates based on utilization, encouraging liquidity when the pool is heavily borrowed.
   • Accrues interest over time using ledger timestamps.
   • Contract: contracts/interest_strategy/src/lib.rs

4. Oracle Interface (The Price Feed)

   • Provides a price feed for collateral valuation in USD terms.
   • Used by the collateral contract to enforce healthy collateral ratios and trigger liquidations.
   • Contract: contracts/oracle_interface/src/lib.rs

5. SEP-41 Token Interfaces

   • All token transfers use Soroban’s SEP-41 compatible token interface for USDC (liquidity) and collateral assets.
   • require_auth() is used to enforce user signatures for deposits, withdrawals, and repayments.

Project layout

• contracts/lending_pool/src/lib.rs
• contracts/collateral_liquidation/src/lib.rs
• contracts/interest_strategy/src/lib.rs
• contracts/oracle_interface/src/lib.rs

Note on prior monolithic prototype

The earlier single-contract prototype is kept only as a reference and is not the recommended deployment path. The modular contracts above are the intended design for production.