Consensus

op-alloy-consensus crate

The op-alloy-consensus crate provides an Optimism consensus interface. It contains constants, types, and functions for implementing Optimism EL consensus and communication. This includes an extended OpTxEnvelope type with deposit transactions, and receipts containing OP Stack specific fields (deposit_nonce + deposit_receipt_version).

In general a type belongs in this crate if it exists in the alloy-consensus crate, but was modified from the base Ethereum protocol in the OP Stack. For consensus types that are not modified by the OP Stack, the alloy-consensus types should be used instead.

Block

op-alloy-consensus exports an Optimism block type, OpBlock.

This type simply re-uses the alloy-consensus block type, with OpTxEnvelope as the type of transactions in the block.

Transactions

Optimism extends the Ethereum EIP-2718 transaction envelope to include a deposit variant.

OpTxEnvelope

The OpTxEnvelope type is based on Alloy's TxEnvelope type.

Optimism modifies the TxEnvelope to the following.

  • Legacy
  • EIP-2930
  • EIP-1559
  • EIP-7702
  • Deposit

Deposit is a custom transaction type that is either an L1 attributes deposit transaction or a user-submitted deposit transaction. Read more about deposit transactions in the specs.

Transaction Types (OpTxType)

The OpTxType enumerates the transaction types using their byte identifier, represents as a u8 in rust.

Receipt Types

Just like op-alloy-consensus defines transaction types, it also defines associated receipt types.

OpReceiptEnvelope defines an Eip-2718 receipt envelope type modified for the OP Stack. It contains the following variants - mapping directly to the OpTxEnvelope variants defined above.

  • Legacy
  • EIP-2930
  • EIP-1559
  • EIP-7702
  • Deposit

There is also an OpDepositReceipt type, extending the alloy receipt type with a deposit nonce and deposit receipt version.