Lab 3: EIP-7702 prep — batch "approve + pay" from an EOA

Time: ~40 min. Goal: see what a 7702 delegation does, locally, before XDC mainnet has Prague.

Status: Ethereum mainnet has 7702 since Pectra; XDC devnet has it, XDC Apothem activates Prague at

block 84,333,000; XDC mainnet (chain 50) is still Cancun. So: anvil / forge only.

Steps

Exercises are the numbered comments in the starter files.

cd lab3 && forge install foundry-rs/forge-std@v1.17.0 --no-git && forge build (foundry.toml sets evm_version = "prague").
Complete Exercises 1-3 in src/BatchExecutor.sol (delegate code for the EOA).
Write Exercises 4-7 in test/BatchExecutor.t.sol. Key cheatcode: vm.signAndAttachDelegation(impl, key)

(keys from makeAddrAndKey, throwaway).

forge test -vv until green. Check: alice.code == 0xef0100 || impl (23 bytes).
Optional on anvil (local only): anvil --port 18513 --hardfork prague, deploy BatchExecutor with

forge create, then send a type-4 tx with `cast send <eoa> 'execute((address,uint256,bytes)[])' '[...]'

--auth <impl> --private-key <anvil test key of that EOA> --rpc-url anvil, then cast code <eoa> --rpc-url anvil`.

Why msg.sender == address(this)? Without it anyone could drive the EOA.
Sponsored version: sign nonce + target + calldata + value + gas (EIP-7702 security section).
tx.origin == msg.sender no longer proves "top-level EOA call".
Storage collisions when switching delegates (ERC-7201 namespaced storage).

Solution: lab3-solution.tar.gz (download link below; same layout, run the same forge install step first).