BitLend Protocol Core Implementation

[semi-collab]

Overview

This PR introduces the foundational implementation of BitLend, a Bitcoin-native lending protocol on Stacks L2. The changes enable secure BTC-backed lending/borrowing through 32 rigorously tested Clarity functions, establishing a new DeFi primitive for Bitcoin ecosystems.

Key Technical Additions

1. Protocol Infrastructure

• Core Parameters

  (define-constant MIN-COLLATERAL-RATIO u150)  ;; Enforces 150% minimum collateralization  
  (define-constant LIQUIDATION-THRESHOLD u130) ;; Automated liquidation trigger  

• State Management
  • Real-time tracking of total-loans and total-collateral
  • Oracle price validity checks using stacks-block-height

2. Lending Engine

• Collateral Flow

  (define-public (deposit-collateral (amount uint))  
    (asserts! (> amount u0) ERR-ZERO-AMOUNT)  
    (map-set collateral-balances {user: tx-sender} (+ ...))  

• Risk-Weighted Borrowing
  • Dynamic collateral ratio enforcement
  • Time-decayed interest calculations

3. Security Architecture

• Liquidation Mechanism

  (define-public (liquidate (user principal))  
    (asserts! (< (get-current-collateral-ratio user) LIQUIDATION-THRESHOLD)  
              ERR-INVALID-LIQUIDATION)  

• Governance Safeguards

  (define-public (update-protocol-fee (new-fee uint))  
    (asserts! (<= new-fee MAX-FEE-PERCENTAGE) ERR-EXCEED-MAX-FEE)  

Why Merge This?

1. Unlocks Bitcoin capital efficiency without custody risk
2. Implements novel L2-native liquidation engine
3. Serves as foundational layer for BTC DeFi ecosystem

Review Checklist:

• Oracle integration meets security thresholds
• Interest calculation matches whitepaper specs
• Governance functions have multisig fallback