Hardfork.hasEIP1559

import { Hardfork } from 'tevm'

function buildTransaction(fork: BrandedHardfork, params: TxParams) {
  if (fork.hasEIP1559()) {
    return {
      type: 2,  // EIP-1559
      maxFeePerGas: params.maxFee,
      maxPriorityFeePerGas: params.tip
    }
  }

  return {
    type: 0,  // Legacy
    gasPrice: params.gasPrice
  }
}

import { Hardfork } from 'tevm'

function calculateGasPrice(
  fork: BrandedHardfork,
  baseFee: bigint,
  maxPriorityFee: bigint
): bigint {
  if (fork.hasEIP1559()) {
    return baseFee + maxPriorityFee
  }

  // Pre-EIP-1559: fixed gas price
  return baseFee
}

import { Hardfork } from 'tevm'

function getFeeMarketConfig(fork: BrandedHardfork) {
  if (fork.hasEIP1559()) {
    return {
      baseFeeChangeDenominator: 8,      // 12.5% max change
      elasticityMultiplier: 2,          // 2x target gas limit
      baseFeeMaxChangeDenominator: 8
    }
  }

  return null  // No dynamic base fee
}

import { Hardfork } from 'tevm'

function getBaseFeeOpcode(fork: BrandedHardfork): number | null {
  if (fork.hasEIP1559()) {
    return 0x48  // BASEFEE opcode
  }

  return null  // Not available
}

import { Hardfork, LONDON } from 'tevm'

function validateEIP1559Support(config: NetworkConfig) {
  const fork = Hardfork(config.hardfork)

  if (!fork.hasEIP1559()) {
    throw new Error(
      `Network ${config.name} does not support EIP-1559. ` +
      `Requires London or later, got ${Hardfork.toString(fork)}`
    )
  }
}