open-sourcing another piece of the cross-chain swap puzzle

a framework for settling swaps on destination chains, handling disputes between fillers & redirecting MEV to swappers in the process:

Tribunal ☝️

https://github.com/Uniswap/Tribunal

let's get into what Tribunal's about 💬

so there are two "sides" to a cross-chain swap using The Compact or other resource locks

the "fill side" is the chain where their output tokens are received

the "claim side" is the chain where their input tokens are held & claimed by a filler

most development effort thus far for The Compact has focused on the claim side

that's where the resource locks are, of course

allocators (mediating resource locks) & arbiters (processing claims) both live on the claim side too

but arbiters need to act on a cross-chain action

this initial version of Tribunal is focused on fill side chains with sequencers that enforce priority ordering

this just means the sequencer orders all transactions in the block by gas price

it's the de-facto behavior on all OP-stack chains today, & Unichain will enforce this

if a chain commits to priority ordering, you can actually run a fair auction where any filler can compete to fill the swap

the output tokens the filler will pay are increased (or the input tokens they can claim are decreased) based on the priority fee

it's beautifully simple

for chains that don't use priority ordering, you can change out the priority tax mechanic and use something like a reverse dutch auction or an RFQ where the filler is selected based on a quote

there's also a "directive" that maps to a cross-chain message Tribunal will dispatch

check it out, make some PRs, and stay posted as the onslaught of repos continues over the coming weeks and months

we'll get there sooner than many expect — and we'll get there faster by working together

mad respect for all the builders jumping into my DMs with q's & making PRs

that's where Tribunal comes in

it serves two core functions

first, it protects fillers from settling a swap that another filler got to first

second, it protects swappers from having claims processed from unrelated payments (like if you tried to do 2 cross-chain swaps at once)