Add Contingent Beneficiaries to Inheritance Contract

[ONEONUORA]

Component: Contracts (Inheritance) | Effort: 4-5 days | Priority: MEDIUM

Current State

Only primary beneficiaries supported. No contingent/backup beneficiaries.

Missing Functions

Contingent beneficiary functions:

• add_contingent_beneficiary() - Add backup beneficiary
• remove_contingent_beneficiary() - Remove backup
• get_contingent_beneficiaries() - List contingent beneficiaries
• promote_contingent() - Promote contingent to primary if primary can't claim
• set_contingency_conditions() - Set conditions for contingent activation

Why This Matters

• Backup plan: If primary beneficiary dies or can't claim
• Estate planning: Standard practice in wills
• Completeness: Ensures assets always have recipient
• Legal requirement: Many jurisdictions require contingent beneficiaries

Tasks

• Add ContingentBeneficiary struct
• Add beneficiary_type enum (Primary, Contingent)
• Implement add_contingent_beneficiary() function
• Add remove_contingent_beneficiary() function
• Implement contingency activation logic
  • Primary beneficiary fails to claim within X days
  • Primary beneficiary explicitly declines
  • Primary beneficiary deceased (oracle)
• Add promote_contingent() function
• Implement get_contingent_beneficiaries() view
• Add contingency timeout configuration
• Add ContingentPromoted event
• Add tests for contingent scenarios
• Document contingent beneficiary system

Acceptance Criteria

• Contingent beneficiaries can be added
• Contingents promoted when primary fails
• Allocation transfers correctly
• Timeout mechanism works
• Tests cover promotion scenarios
• Documentation explains contingency rules