LP-5101: Solidity GraphQL Extension for Native G-Chain Integration

See also: LP-1200: C-Chain EVM Specification, LP-1226: C-Chain EVM Equivalence, LP-0098: GraphDB & GraphQL Integration

Abstract

This LP introduces a Solidity language extension that embeds GraphQL query syntax directly into smart contracts, enabling native integration with G-Chain from C-Chain contracts. The extension includes:

GraphQL query literals with compile-time validation
Automatic code generation for type-safe query results
Gas-efficient precompile calls to G-Chain
Built-in caching and result pagination
Quantum-safe query authentication

This allows developers to write cross-chain queries as naturally as they write regular Solidity code, dramatically simplifying dApp development across Lux's 8-chain architecture.

Motivation

Current cross-chain data access from smart contracts is complex and error-prone:

Manual ABI encoding/decoding for cross-chain calls
No compile-time validation of queries
Type safety lost between query and result handling
High gas costs for complex data retrieval
No standard patterns for caching or pagination

By embedding GraphQL directly in Solidity, we can:

Validate queries at compile time
Generate type-safe result structs automatically
Optimize gas usage through precompiles
Provide intuitive syntax familiar to web developers
Enable complex cross-chain queries with minimal code

Specification

GraphQL Query Syntax

Introduce a new query keyword for GraphQL literals:

pragma solidity ^0.8.24;
pragma experimental GraphQL;

contract DeFiAggregator {
    // GraphQL query defined at contract level
    query GetUserPositions {
        """
        query UserPortfolio($user: Address!, $chains: [ChainID!]) {
            positions(owner: $user, chains: $chains) {
                chain
                protocol
                asset {
                    symbol
                    decimals
                    address
                }
                amount
                valueUSD
            }
            totalValueUSD: aggregate(fn: SUM, field: valueUSD)
        }
        """
    }
    
    // Auto-generated struct from query
    struct UserPortfolioResult {
        Position[] positions;
        uint256 totalValueUSD;
    }
    
    struct Position {
        string chain;
        string protocol;
        Asset asset;
        uint256 amount;
        uint256 valueUSD;
    }
    
    struct Asset {
        string symbol;
        uint8 decimals;
        address address;
    }
}

Rationale

Embedding GraphQL enables compile‑time validation and type safety, reducing cross‑chain query bugs.
A precompile abstracts transport details, allowing gas‑efficient execution without bespoke bridges.
Familiar GraphQL syntax lowers the learning curve for web developers building Lux dApps.

Query Execution

Queries are executed through a special precompile at 0x0100:

function getUserPortfolio(address user) external view returns (UserPortfolioResult memory) {
    // Compiler generates this call
    bytes memory queryData = abi.encode(
        GetUserPositions.selector,
        user,
        ["C", "X", "A"] // chains parameter
    );
    
    (bool success, bytes memory result) = address(0x0100).staticcall(queryData);
    require(success, "GraphQL query failed");
    
    return abi.decode(result, (UserPortfolioResult));
}

Inline Queries

Support inline queries for dynamic use cases:

function getTokenPrice(address token) external view returns (uint256) {
    // Inline query with automatic type inference
    var result = query {
        """
        query TokenPrice($token: Address!) {
            token(address: $token) {
                priceUSD
                liquidity
                volume24h
            }
        }
        """
    } with { token: token };
    
    return result.token.priceUSD;
}

Query Modifiers

Support common GraphQL operations:

// Pagination
query GetTransactions {
    """
    query RecentTxs($user: Address!, $limit: Int = 10, $offset: Int = 0) {
        transactions(from: $user, limit: $limit, offset: $offset) @paginate {
            hash
            to
            value
            timestamp
        }
    }
    """
}

// Caching
query GetStats {
    """
    query ProtocolStats @cache(ttl: 300) {
        stats {
            tvl
            users
            transactions
        }
    }
    """
}

// Real-time subscriptions (for off-chain watchers)
query WatchPrices {
    """
    subscription PriceUpdates($pairs: [String!]) @realtime {
        priceUpdate(pairs: $pairs) {
            pair
            price
            timestamp
        }
    }
    """
}

Cross-Chain Aggregation

Enable complex cross-chain queries:

query GetCrossChainBalance {
    """
    query TotalBalance($user: Address!, $token: String!) {
        chains {
            id
            name
            balance(owner: $user, symbol: $token) {
                amount
                valueUSD
            }
        }
        total: aggregate(
            source: chains.balance.valueUSD,
            fn: SUM
        )
    }
    """
}

function getTotalUSDValue(address user, string memory token) 
    external view returns (uint256) 
{
    var result = GetCrossChainBalance.execute(user, token);
    return result.total;
}

Gas Optimization

The compiler optimizes GraphQL queries:

Query Deduplication: Identical queries share bytecode
Result Caching: Built-in result caching with TTL
Batch Queries: Multiple queries in single precompile call
Lazy Loading: Only requested fields are returned

// Batch multiple queries
function getDefiStats(address user) external view {
    var results = query.batch {
        positions: GetUserPositions(user, ["C", "X"]),
        prices: GetTokenPrices(["LUX", "ETH", "USDC"]),
        apr: GetPoolAPR(user.activePools)
    };
    
    // Process results...
}

Type Safety

The compiler ensures type safety:

// Compile error: field doesn't exist
var price = result.token.notAField; // Error!

// Compile error: type mismatch
uint256 symbol = result.token.symbol; // Error: string to uint256

// Automatic type coercion where safe
uint256 amount = result.balance; // OK if balance is numeric

Security Features

All queries are quantum-safe:

modifier onlyWithAttestation() {
    // Queries automatically include attestation
    require(msg.sender.hasValidAttestation(), "Invalid attestation");
    _;
}

function secureQuery() external view onlyWithAttestation {
    // Query includes dual-certificate signature
    var result = query {
        """
        query SecureData @authenticated {
            sensitiveData {
                value
                proof
            }
        }
        """
    };
}

Implementation

Compiler Extensions

Parser: Recognize query keyword and GraphQL syntax
Validator: Validate GraphQL syntax at compile time
Type Generator: Generate Solidity structs from GraphQL schema
Code Generator: Generate efficient precompile calls
Optimizer: Deduplicate queries and optimize gas usage

Runtime Support

Precompile 0x0100: G-Chain query executor
Result Cache: In-memory cache for query results
Schema Registry: On-chain GraphQL schema storage
Query Validator: Runtime query validation

Development Tools

IDE Support: Syntax highlighting and autocomplete
Schema Generator: Generate GraphQL schema from contracts
Query Builder: Visual query builder for Solidity
Gas Estimator: Estimate query gas costs
Testing Framework: Mock G-Chain responses

Example Use Cases

DeFi Aggregator

contract DeFiAggregator {
    query FindBestRate {
        """
        query BestSwapRate($tokenIn: String!, $tokenOut: String!, $amount: BigInt!) {
            dexes {
                protocol
                rate(from: $tokenIn, to: $tokenOut, amount: $amount)
                liquidity
                fee
            }
            best: max(source: dexes.rate)
        }
        """
    }
    
    function swap(address tokenIn, address tokenOut, uint256 amount) external {
        var result = FindBestRate.execute(tokenIn.symbol(), tokenOut.symbol(), amount);
        IDex(result.best.protocol).swap(tokenIn, tokenOut, amount);
    }
}

NFT Marketplace

contract NFTMarketplace {
    query GetNFTHistory {
        """
        query NFTProvenance($collection: Address!, $tokenId: BigInt!) {
            nft(collection: $collection, id: $tokenId) {
                creator
                owners {
                    address
                    acquiredAt
                    price
                }
                attributes
                metadata
            }
        }
        """
    }
}

Cross-Chain Bridge

contract UniversalBridge {
    query CheckBridgeLiquidity {
        """
        query BridgeLiquidity($token: String!, $amount: BigInt!) {
            chains {
                id
                name
                liquidity(token: $token) {
                    available
                    sufficient: gte(available, $amount)
                }
            }
            viableChains: filter(
                source: chains,
                where: liquidity.sufficient == true
            )
        }
        """
    }
}

Test Cases

1. Basic Query Compilation

// Test: Query compiles and generates correct struct
pragma solidity ^0.8.24;
pragma experimental GraphQL;

contract TestBasicQuery {
    query GetBalance {
        """
        query Balance($user: Address!) {
            account(address: $user) {
                balance
            }
        }
        """
    }

    function test_queryCompiles() public view {
        address user = address(0x1234);
        var result = GetBalance.execute(user);
        assert(result.account.balance >= 0);
    }
}

2. Type Safety Enforcement

// Test: Compiler rejects type mismatches
contract TestTypeSafety {
    query GetUser {
        """
        query User($id: BigInt!) {
            user(id: $id) {
                name
                age
            }
        }
        """
    }

    function test_typeMismatchFails() public {
        // This should fail at compile time:
        // string memory age = GetUser.execute(1).user.age; // Error: uint to string

        // This should succeed:
        uint256 age = GetUser.execute(1).user.age;
        string memory name = GetUser.execute(1).user.name;
    }
}

3. Cross-Chain Aggregation

// Test: Multi-chain query returns aggregated results
contract TestCrossChain {
    query GetMultiChainBalance {
        """
        query TotalBalance($user: Address!) {
            chains {
                id
                balance(owner: $user)
            }
            total: aggregate(source: chains.balance, fn: SUM)
        }
        """
    }

    function test_crossChainAggregation() public view {
        address user = msg.sender;
        var result = GetMultiChainBalance.execute(user);

        // Verify all chains returned
        assert(result.chains.length == 8); // All 8 Lux chains

        // Verify aggregation
        uint256 sum = 0;
        for (uint i = 0; i < result.chains.length; i++) {
            sum += result.chains[i].balance;
        }
        assert(result.total == sum);
    }
}

4. Caching Behavior

// Test: Cached queries return consistent results
contract TestCaching {
    query GetCachedData {
        """
        query Stats @cache(ttl: 300) {
            stats {
                tvl
                timestamp
            }
        }
        """
    }

    function test_cacheHit() public view {
        var result1 = GetCachedData.execute();
        var result2 = GetCachedData.execute();

        // Within TTL, results should be identical
        assert(result1.stats.timestamp == result2.stats.timestamp);
    }
}

5. Gas Metering

// Test: Complex queries respect gas limits
contract TestGasLimits {
    query GetLargeDataset {
        """
        query AllTransactions($limit: Int!) {
            transactions(limit: $limit) {
                hash
                from
                to
                value
            }
        }
        """
    }

    function test_gasLimitEnforced() public view {
        uint256 gasBefore = gasleft();
        var result = GetLargeDataset.execute(1000);
        uint256 gasUsed = gasBefore - gasleft();

        // Verify gas consumption is within expected bounds
        assert(gasUsed < 500000); // Max 500k gas for query
        assert(result.transactions.length <= 1000);
    }
}

6. Precompile Integration

// Test: Direct precompile call returns valid response
contract TestPrecompile {
    address constant G_CHAIN_PRECOMPILE = address(0x0100);

    function test_precompileCall() public view {
        bytes memory queryData = abi.encode(
            bytes4(keccak256("ping()")),
            ""
        );

        (bool success, bytes memory result) = G_CHAIN_PRECOMPILE.staticcall(queryData);
        assert(success);
        assert(result.length > 0);
    }
}

7. Error Handling

// Test: Invalid queries revert with descriptive errors
contract TestErrorHandling {
    query GetInvalidField {
        """
        query InvalidQuery {
            nonexistent {
                field
            }
        }
        """
    }

    function test_invalidQueryReverts() public view {
        // Should revert with "GraphQL: unknown field 'nonexistent'"
        try this.executeInvalid() {
            revert("Should have reverted");
        } catch Error(string memory reason) {
            assert(bytes(reason).length > 0);
        }
    }

    function executeInvalid() external view {
        GetInvalidField.execute();
    }
}

8. Batch Query Execution

// Test: Batch queries execute atomically
contract TestBatchQueries {
    function test_batchExecution() public view {
        var results = query.batch {
            balance: GetBalance(msg.sender),
            prices: GetPrices(["LUX", "ETH"]),
            stats: GetProtocolStats()
        };

        // All queries should succeed or all should fail
        assert(results.balance.account.balance >= 0);
        assert(results.prices.length == 2);
        assert(results.stats.tvl > 0);
    }
}

Backwards Compatibility

This extension is opt-in via pragma experimental GraphQL. Contracts without this pragma are unaffected. The feature can be enabled per-contract, allowing gradual adoption.

Security Considerations

Query Injection: Queries are parsed at compile-time, preventing injection
Gas Limits: Queries respect block gas limits via precompile metering
Access Control: Queries inherit contract's access control
Result Validation: Results are validated against schema
Quantum Safety: All queries use dual-certificate authentication

Future Enhancements

Query Composition: Reuse query fragments
Schema Evolution: Automatic migration for schema changes
Off-chain Execution: Execute queries in view functions
Query Optimization: AI-powered query optimization
Cross-Contract Queries: Share queries between contracts

Conclusion

By embedding GraphQL directly into Solidity, we dramatically simplify cross-chain dApp development on Lux. Developers can write complex queries with the same ease as calling a local function, while the compiler handles all the complexity of cross-chain communication, type safety, and gas optimization.

Solidity GraphQL Extension for Native G-Chain Integration