Superchain and the Monolithic Experience - A cross-chain guide for Superchain

Hey Optimism Collective, I’m Sandman, a researcher associated with Delphi Digital who worked on the cross-chain report for Superchain.

For context, here’s the RFG for the Cross-Chain Interoperability research (RFG-8): Link
Here’s Delphi’s proposal: Link

And here’s the full report we worked on: Link

In a nutshell
To start with, we go into some important concepts in the cross-chain context to help understand the whole report better. We define Token Bridges, Messaging Bridges and the rest of the components in the interoperability stack as we will be discussing which parts of the stack Optimism should focus on and why.

We then dive into various stakeholders like Users, dApp Builders and Chain Builders, and what are their preferences are when it comes to interoperability. For example,

  1. Users care about user experience, costs of interoperability and the security of the tokens they are holding
  2. Whereas dApp Builders care about interop standards, composability and abstraction of permissions, etc.
  3. And Chain Builders care about the sovereignty, MEV extraction (or prevention) and reorg dependencies, etc.
    Optimism needs to satisfy each of these stakeholders before making major changes to the Superchain stack.

Then we look at how other ecosystems similar to Superchain have approached the interop problem and how they are planning to. We also compare how these solutions affect each of their stakeholders (users, dapp builders, and chain builders).

We believe shared sequencing is a powerful solution that can solve many of our problems. The next evolution of shared sequencing, which is based sequencing, is the best solution to the Ethereum interop problem. We believe this decision is an important one that should be made with a lot of discussions.

The Main Part
We later make suggestions on the directions Superchain should take. There are many directions Superchain can choose to go into. Every option we list trades off one factor for another.
1. No Changes to the Base Layer: We explore what it would look like to let the market figure it out for themselves. Interop will be solved one way or the other. Superchain may choose to solve it or let new teams pop up to solve it. Chain builders benefit here the most as they get to retain their sovereignty. We do not recommend this, for the sake of our industry.
2. Asynchronous Composability: In this approach, Superchain chooses to offer trustless interop between chains thus solving interop to a very good extent, but does not offer the complete solution. This may limit what dApp Developers can build on Superchain.
3. Shared Validity Sequencing: This seems to be the approach Optimism is taking right now. Although a great approach, we believe it trades off permissionless interop with all the old and new OP Stack chains. Chains will have to be super vary about who they interop with as there can be frequent rollbacks via fraud proofs.
4. zk-Aggregation Layer: If OP Stack chooses to turn into a zk-rollup, this solutions seems to be the best option available. The main tradeoff is giving up the benefits of Optimistic rollups. On the other side, it is possible to achieve secure atomic execution natively across all of the aggregated chains.
5. Shared Sequencer Networks: A shared sequencing network solution built to offer interoperability as a feature. The chain builders lose part of their sovereignty if they opt in. But gain interop and decentralization.
6. Based Sequencing: Based Sequencing is about interop with the L1. We believe this should be the ultimate goal for rollups. With this approach, Ethereum can work as a monolithic chain while retaining the benefits of the fragmented rollups.

Finally, we roughly gauge the amount of effort required by various stakeholders to offer the monolithic experience to their stakeholders.

This TLDR version just scratches the surface. Please go through the entire report, ask questions and voice your opinions in the thread below. Thank you.

And I thank Mark Murdock, Can Gurel, Ceteris, Facundo and the rest of the Delphi Team for comments and feedback.