Add Loan Insurance & Protection to Lending Contract

[ONEONUORA]

Component: Contracts (Lending) | Effort: 5-7 days | Priority: MEDIUM

Current State

No loan insurance or protection mechanism for borrowers.

Missing Functions

Loan insurance functions:

• purchase_loan_insurance() - Buy insurance for loan
• get_insurance_premium() - Calculate insurance cost
• claim_insurance() - Claim insurance on default
• get_insurance_coverage() - Get coverage amount
• is_loan_insured() - Check if loan has insurance
• cancel_insurance() - Cancel insurance and get refund

Why This Matters

• Risk mitigation: Protect borrowers from liquidation
• Revenue: Insurance premiums generate income
• User confidence: Borrowers feel safer
• Competitive advantage: Unique feature

Tasks

• Add LoanInsurance struct (loan_id, coverage_amount, premium_paid, expires_at)
• Implement purchase_loan_insurance() function
  • Calculate premium (e.g., 2% of loan amount)
  • Transfer premium to insurance fund
  • Store insurance record
  • Emit InsurancePurchased event
• Add get_insurance_premium() calculation
• Implement claim_insurance() function
  • Validate loan defaulted
  • Pay insurance claim
  • Cover loan from insurance fund
  • Emit InsuranceClaimed event
• Add insurance coverage limits
• Implement insurance expiration
• Add cancel_insurance() with partial refund
• Track insurance fund balance
• Add tests for insurance scenarios
• Document insurance system

Acceptance Criteria

• Borrowers can purchase insurance
• Premiums calculated correctly
• Insurance claims processed
• Coverage limits enforced
• Tests cover insurance lifecycle
• Documentation complete