Feat/generate contract interfaces

[allenday]

Add Contract Interface Generation from Proto Services

Overview

This PR adds the ability to generate Solidity contract interfaces directly from Protocol Buffer service definitions, enabling true proto-first blockchain development.

What This Adds

Service-to-Interface Generation

• Generates Solidity interface declarations from proto service definitions
• Maps proto RPC methods to Solidity function signatures
• Maintains type safety between proto definitions and contract implementations

Type System Integration

• Automatic type mapping from proto fields to Solidity types
• Support for complex nested message types
• Generic library naming for reusable components

Development Workflow

• Proto services define contract APIs
• Generated interfaces ensure compile-time compliance
• Contracts implement generated interfaces, not ad-hoc signatures

Example

Proto Service Definition:

service ContractInterface {
  rpc RegisterIdentity(RegisterIdentityRequest) returns (RegisterIdentityResponse);
  rpc GetIdentities(GetIdentitiesRequest) returns (GetIdentitiesResponse);
}

Generated Solidity Interface:

interface IContractInterface {
    function registerIdentity(string memory domain, string memory identifier)
        external returns (bool success, string memory error, string memory transaction_hash);
    function getIdentities()
        external returns (StandaloneAttestorStandaloneIdentity.Data[] memory identities);
}

Contract Implementation:

contract MyContract is IContractInterface {
    // Compiler enforces interface compliance
    function registerIdentity(string memory domain, string memory identifier)
        external override returns (bool success, string memory error, string memory transaction_hash) {
        // Implementation
    }
}

Benefits

• Single Source of Truth: Proto files define both frontend types and backend contracts
• Type Safety: Compile-time verification that contracts match specifications
• Consistency: Same API structure across different implementations
• Maintainability: Proto changes automatically propagate to generated interfaces

Files Changed

• src/protoc/plugin/gen_sol.py: Added gen_contract_interface() function and service processing
• README.md: Added comprehensive documentation with examples

Testing

This feature has been validated with a real-world attestor contract implementation, demonstrating:

• Successful interface generation from complex proto services
• Contract compilation with interface inheritance
• Full test suite compatibility with generated interfaces

Backward Compatibility

This change is fully backward compatible. Existing proto files that only contain messages will continue to work exactly as before. The new interface generation only activates when proto services are present.