Upgradeability Layer

As mentioned in the preface, most rollups today have an enshrined bridge to Ethereum. This bridge keeps track of the rollup state, validates fraud proofs (or validity proofs for ZK rollups) and allows withdrawal of assets from the rollup to Ethereum. However, these enshrined bridges are mostly controlled via a multisig wallet and therefore the bridge has the ability to arbitrarily steal funds from users via a malicious upgrade. Beacon Layer acts as a social layer for upgrades for all the rollups enshrined to it. Sequencers that register to operate a rollup together with the Beacon Layer rollup validators can socially fork the rollup regardless of whether or not the enshrined bridge contract on Ethereum gets upgraded. Recall that an enshrined bridge is only an observer of the rollup like every other rollup validator.

Sequencers and rollup validators on the Beacon Layer who do not agree with the fork may decide to not support the new fork.