--- tags: epf, ethereum --- # EPF Dev Update #6 ## Builder API updates for Blobs (EIP-4844) Last week, I drafted out the Builder spec changes required for EIP-4844 in [this doc](https://hackmd.io/@jimmygchen/B1dLR74Io), and since then I've worked with **@0xGabi** and created PRs on the specs: - Beacon API PR [here](https://github.com/ethereum/beacon-APIs/pull/271) - Builder spec PR [here](https://github.com/ethereum/builder-specs/pull/58) There are still some open questions there, but it's great to get the PR out there to get some discussions started, and hopefully we'll get some feedback soon. We think it would be great to start testing the external builder flow early in the process. This week I'll be looking into testing in the following areas: - Builder test tool updates for blobs, [code here](https://github.com/sigp/lighthouse/blob/24e5252a55148f8a49e806f2e0943cb834042b31/beacon_node/execution_layer/src/test_utils/mock_builder.rs#L66) - [interop](https://github.com/Inphi/eip4844-interop) & [devnet v3](https://notes.ethereum.org/@timbeiko/4844-devnet-3) testing - create test vectors for [mev-boost](https://github.com/flashbots/mev-boost) to run tests against CLs [Link to Project Proposal](https://github.com/eth-protocol-fellows/cohort-three/blob/master/projects/4844-consensus-client.md )