What DevEx improvements can we add for 7702 transaction interactions?

[fselmo]

What feature should we add?

EIP-7702 is working well with manual transaction signing via ethereum/eth-account#316. There are undoubtedly better ways to interact and build 7702 transactions than currently exist within web3.py. Today we must do something like:

(untested, pseudocode-ish)

# get the contract of interest, as an example
contract = w3.eth.contract(address=contract_address, abi=contract_abi)

acct = Account.from_key(my_key)
signed_auth = acct.sign_authorization({
    "address": contract.address,
    "nonce": w3.eth.get_transaction_count(acct) + 1,
    "chainId": w3.eth.chain_id,
})

# extract the data for the desired contract interaction
contract_call = contract.functions.myFunction(arg1, arg2).build_transaction()

tx = {
    "to": acct.address,
    ...
    "authorizationList": [signed_auth],
    "data": contract_call["data"],
}
signed_tx = acct.sign_transaction(tx)

w3.eth.send_raw_transaction(signed_tx.raw_transaction)

The goal would be to improve the DevEx to build and send a 7702 transaction. I believe this likely has to exist at the web3.py, not the eth-account level, as we should have access to the web3 object to facilitate eth_chainId, eth_getTransactionCount (nonce), eth_estimateGas calls, contract call data collection, etc.

---

Loosely, if I have a known contract and ABI, I'd like to be able to say take this account, authorize this account to behave like that contract, and build my transaction with this auth inside the "authorlzationList" while making the first call to function A on the contract. It may also be better to have a builder where there can be many iterations of this to build a single transaction with many such auths.

[darwintree]

The provided code might not be good enough. I would provide an improved version, but still needs improvement

# get the contract of interest, as an example
contract_factory = w3.eth.contract(abi=contract_abi)

acct = Account.from_key(my_key)

# setting signing middleware here
w3.middleware_onion.inject(0, Signxxxx.build(acct))
w3.eth.default_account = acct.address

signed_auth = acct.sign_authorization({
    "address": contract.address,
    "nonce": w3.eth.get_transaction_count(acct) + 1,  // should plus 1 here
    "chainId": w3.eth.chain_id,
})
self_contract = contract_factory(acct.address)

# use self_contract to send
tx_hash = self_contract.functions.myFunction(arg1, arg2).transact({
    "authorizationList": [signed_auth]
})

I think the improvements should lie in the auth signing, here is what I think would be better:

1. can provide signed authorization in tx param authorizationList as well as a list to sign
2. can automatically fill the right nonce for authorization

For example

authorizationList = [{
    "address": contract.address,
    // "nonce": w3.eth.get_transaction_count(acct) + 1,  // can be automatically selected by web3
    // "chainId": w3.eth.chain_id, // can be automatically selected by web3, using current chain_id as default
    "signer": signer, // can be either an address or an eth_account object, or NotRequired which means signed by default_account
}]

A full new example:

# get the contract of interest, as an example
contract_factory = w3.eth.contract(abi=contract_abi)

acct = Account.from_key(my_key)

# setting signing middleware here
w3.middleware_onion.inject(0, Signxxxx.build(acct))
w3.eth.default_account = acct.address

self_contract = contract_factory(acct.address)

# use self_contract to send
tx_hash = self_contract.functions.myFunction(arg1, arg2).transact({
    "authorizationList": [{
        "address": contract_address
    }]
})

[Rango305]

Another small Addition might be A Builder Class Just for 7702

“Why can’t this just… work?”
Give devs a slick builder that handles the auth list and data packing:

builder = w3.eth.EIP7702TxBuilder(acct)
builder.add_call(
    my_contract.functions.doSomething(123), 
    auth_for_contract_X  # Optional if you need multiple auths
)
tx = builder.build()  # Auto-adds gas, nonce, etc.

Bonus: Let it handle batch auths + multi-contract calls in one TX.

[wolovim]

couple notes while prototyping:

• eth_call cant simulate the tx, because auth list/SignedSetCodeAuth.. isnt serializable
• estimate gas doesnt work for type 4 tx and manual gas setting sucks (especially on sepolia)
• tangentially related: manually building calldata for multicall use is painful (e.g., contract.encode_abi...). as rango suggests above, could be nice to leverage the existing batch patterns. if you go far enough in this direction, you probably end up with a native multicall API, but that's a side quest.
• will continue to mull over entire new API domains, like the 7702TxBuilder, but web3.py can also supply minor niceties, like auto nonce management in the "bare metal" versions.