Updated logic for remove the paymaster remaining code and adapt for the simplified MVP schema

[0xarcano]

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Pull Request: Implement Signature-Based Minting and SBT Retention

🎯 Overview

This PR implements a major architectural change to the Merch MVP system, replacing the whitelisted minter approach with signature-based minting and ensuring SBTs are retained during companion minting.

🔄 Key Changes

BasicMerch Contract (src/BasicMerch.sol)

• ✅ Removed whitelisted minter system completely
• ✅ Added signature-based minting with mintSBT(address _to, uint256 _eventId, string memory _tokenURI, bytes memory _signature)
• ✅ Added eventId tracking with mappings for user+event to tokenId lookups
• ✅ Added getSBTByEvent() function for looking up SBTs by user and event
• ✅ Removed burnSBT function - SBTs are now permanent
• ✅ Updated _update function to prevent all transfers (SBTs are permanent)
• ✅ Added setBackendIssuer() function for signature verification

PremiumMerch Contract (src/PremiumMerch.sol)

• ✅ Renamed upgradeSBT to mintCompanion
• ✅ Removed all SBT burning logic - SBTs are now retained during companion minting
• ✅ Updated events from SBTUpgraded to CompanionMinted
• ✅ Updated function names and comments to reflect companion minting
• ✅ Verified dual asset ownership - users keep both SBT and Premium NFT

Test Updates

• ✅ BasicMerch tests: Updated to use signature-based minting with helper functions
• ✅ PremiumMerch tests: Updated to verify SBT retention and dual asset ownership
• ✅ Integration tests: Updated to test complete dual-asset flow
• ✅ All tests verify that SBTs are retained after companion minting

Deployment Script Updates (script/DeployMerchMVP.s.sol)

• ✅ Updated configuration to use setBackendIssuer() instead of whitelisted minters
• ✅ Added backend issuer to deployment parameters and JSON output
• ✅ Updated test commands to show signature-based minting and companion minting
• ✅ Updated next steps to reflect new architecture

🚀 New Features

1. Signature-Based Minting: SBTs can only be minted with valid signatures from the backend issuer
2. SBT Retention: When users mint Premium companions, their SBTs are retained (not burned)
3. Dual Asset Ownership: Users can own both SBTs and Premium NFTs simultaneously
4. Event Tracking: SBTs are linked to specific events via eventId
5. Permanent SBTs: SBTs cannot be transferred or burned (true soulbound behavior)

🧪 Testing

All tests have been updated and pass:

• ✅ Signature verification tests
• ✅ SBT retention verification
• ✅ Dual asset ownership tests
• ✅ Integration tests for complete flow
• ✅ Error handling for invalid signatures
• ✅ Duplicate event minting prevention

📋 Breaking Changes

• BasicMerch.mintSBT() now requires eventId and signature parameters
• PremiumMerch.upgradeSBT() renamed to mintCompanion()
• SBTs are no longer burned during companion minting
• Whitelisted minter system removed - replaced with signature verification

🔧 Migration Notes

For existing deployments:

1. Update backend to generate signatures for SBT minting
2. Update frontend to use new mintCompanion() function
3. Users will now retain SBTs after companion minting
4. Update any integration code that relied on SBT burning

📚 Documentation Updates

• Updated contract specifications in context/ folder
• Updated testing strategy to reflect new architecture
• Updated deployment scripts with new configuration

✅ Checklist

• All contracts updated with new logic
• All tests updated and passing
• Deployment scripts updated
• Documentation updated
• No breaking changes to existing functionality (where applicable)
• Comprehensive test coverage for new features

🎯 Impact

This change enables:

• Better UX: Users keep their SBTs as permanent proof of attendance
• Enhanced Security: Signature-based minting prevents unauthorized minting
• Dual Asset Model: Users can own both SBTs and Premium NFTs
• Event Tracking: Better organization of attendance records
• True Soulbound Behavior: SBTs cannot be transferred or burned

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Ready for review and testing on Base Sepolia testnet! 🚀