André from Parity Technologies gives a deep-dive into GRANDPA and BEEFY (Bridge Efficiency Enabling Finality Yielder) consensus gadgets and what problems they solve.

He covers how BEEFY can be coupled together with the Merkle Mountain Range (MMR) pallet to build an efficient, trustless, low-volume light client, which can then be used to bridge different blockchains. We also discuss a design for a Substrate-Etherum bridge and its use of BEEFY + MMR.

Finally, André gives a BEEFY gadget code walkthrough and outlines the implementation details of outstanding issues.