EIPs

EIP-1559 — Fee market change for ETH 1.0 chain

eips.ethereum.org/EIPS/eip-1559

The post-London fee market. Replaces a single gasPrice with maxFeePerGas + maxPriorityFeePerGas on a type-2 transaction, and adds a per-block baseFeePerGas that targets 50% block fullness via geometric adjustment. The type-2 tx wire format, the spec constants, and the base-fee arithmetic all live here.

import {
  transaction1559UnsignedSchema,
  transaction1559SignedSchema,
  encode_transaction_unsigned,
  calculate_base_fee,
  effective_gas_price,
  INITIAL_BASE_FEE,
  BASE_FEE_MAX_CHANGE_DENOMINATOR,
  ELASTICITY_MULTIPLIER,
} from "@ethernauta/eip/1559";

Surface

Wire format

Export	Purpose
`transaction1559UnsignedSchema`, `Transaction1559Unsigned`	The pre-signing payload: `{ chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gas, to, value, input, accessList }`.
`transaction1559SignedSchema`, `Transaction1559Signed`	The signed envelope including `v`, `r`, `s`.
`encode_transaction_unsigned`	RLP encode + `0x02` type prefix. The bytes you hash to produce the signing digest.

Spec constants

Export	Value	Source
`INITIAL_BASE_FEE`	`1_000_000_000n` (1 gwei)	EIP-1559 §“Specification”
`BASE_FEE_MAX_CHANGE_DENOMINATOR`	`8n`	The 12.5%-per-block cap.
`ELASTICITY_MULTIPLIER`	`2n`	Target gas = gas limit / 2.

Arithmetic

Export	Returns	Purpose
`calculate_base_fee`	`bigint`	Next block’s base fee from the parent block’s `(gas_used, gas_limit, base_fee_per_gas)`. The spec formula, port for port.
`effective_gas_price`	`bigint`	What a transaction actually pays: `base_fee + min(max_priority_fee, max_fee - base_fee)`.

Where this used to live

Before the typed-transaction extraction, Transaction1559Unsigned and its codec lived in @ethernauta/eth/core/transaction/1559.ts. Spec arithmetic didn’t exist in the library at all. The move:

Eth now imports from @ethernauta/eip/1559 when its variant unions (signed.ts, unsigned.ts) need the type-2 schema.
eth_feeHistory and eth_maxPriorityFeePerGas stay in @ethernauta/eth — they’re execution-API methods, not EIP-paper-defined.
The dependency edge is now eth → eip, acyclic.

If you’re a consumer: pull Transaction1559Unsigned directly from @ethernauta/eip/1559. Don’t re-export through @ethernauta/eth.

When dapps need this

Most of the time you don’t construct the wire bytes yourself — @ethernauta/gas’s estimate_1559_fees composes the fee triple, and the wallet’s eth_sendTransaction handler does the encoding. You reach for these primitives when you need:

Path-2 signing. Sign + broadcast without a wallet: encode → hash → sign → eth_sendRawTransaction. See Concepts → two paths.
Block-by-block base-fee modeling. Predicting the next N blocks’ base fee via calculate_base_fee.
L2 fee surcharge composition. OP-stack’s getL1Fee(bytes) consumes a serialized type-2 unsigned transaction — that’s encode_transaction_unsigned.