evm-decimal-validation

EVM Token Decimal Validation

Ensure token decimals are correctly configured for each blockchain deployment to prevent amount calculation errors.

Quick Start

1. Check current configuration - Review network configs for decimal fields
2. Validate against contracts - Query on-chain decimals() for each deployment
3. Update configuration - Add per-chain decimals to network config
4. Test conversions - Verify FromWei/ToWei work correctly

Token Decimal Standards

Common Decimal Values

Decimals	Use Case	Examples
18	Standard ERC20 (most tokens)	WETH, DAI, USDC (on some chains)
6	Stablecoins	USDC, USDT (on Ethereum)
8	Bitcoin-wrapped	WBTC
2	Fiat-backed (cents)	IDRX, some CBDCs
0	Raw integers	Some wrapped tokens

Chain-Specific Variations

The same token contract deployed on different chains may use different decimals:

Token A on Ethereum:    18 decimals
Token A on Polygon:     0 decimals (different deployment)
Token A on BNB Chain:   0 decimals (different deployment)

Validation Checklist

Step 1: Audit Current Configuration

# Find hardcoded decimals
grep -rn "18)" --include="*.go" | grep -i "decimal\|wei\|amount"

# Check for decimals field in network config
grep -rn "Decimals" blockchain/networks.go

Step 2: Query On-Chain Values

// Get decimals from contract
decimals, err := contract.Decimals(nil)
if err != nil {
    return fmt.Errorf("failed to get decimals: %w", err)
}

Step 3: Update Network Config

type NetworkConfig struct {
    // ... existing fields ...
    Decimals uint8 // Token decimals for this deployment
}

// In SupportedNetworks
BaseMainnet: {
    // ...
    Decimals: 2, // From on-chain query
},

Step 4: Add Helper Function

// GetDecimals returns token decimals for a chain ID.
// Always provide a sensible fallback.
func GetDecimals(chainID uint64) uint8 {
    config, _, exists := GetNetworkConfigByChainID(chainID)
    if !exists {
        return 2 // Fallback to majority value
    }
    return config.Decimals
}