uniswap-rebate

This is NOT a uniswap v4 hook, but to give fee rebate to pools w/ non-zero hooks address.

See https://github.com/uniswapfoundation/router-rebates/ for more details. Onchain claim code is integrated into Uniswap's contract.

Over the time, scope/requirements have changed multiple times. Latest as of 2025-03-10:

1. swaps may happen on multiple chains that have uniswap v4 deployed. claim only happens on unichain
2. each router impl rebateClaimer() view to indicate which address is allowed to call claim onchain
3. rebate gas cost in Eth. rebate gas for one tx is n * (rebatePerSwap+rebatePerHook) + rebateFixed where n is number of valid swaps in this tx. Then compare the result with tx's actual gas usage * 0.8 and choose the smaller one

Workflow

• Onchain setup: deploy ClaimHelp contract via create2 to address 0x112233C73c74a810BA963171ADc431A60e051D38. For supported routers, call ClaimHelp.claim(router address) which emits event Claimer(address,address), needed later for zk circuit
• projects submit list of tx hashes to Brevis gas rebate server and get a request id
• Brevis server will fetch tx receipts, filter events by poolids (swaps on ineligible pools are ignored), add corresponding Claimer event and start zk proving process
• Brevis server submits internal proof request to Brevis gateway, wait till final proof and onchain calldata becomes available and save to its own db
• projects query Brevis server for calldata and send onchain tx to RouterRebates.claimWithZkProof

ClaimHelp and Create2

Initially we expected router to emit Claimer address but final design only has view func. We deploy a helper contract to call rebateClaimer and emit both router and claimer address. Use create2 to ensure ClaimHelp is deployed at the same address on every supported chain.

• Claimer(address,address) event ID: 0xf0d796bb38c321bf748f9334d1b7b16ba5fb79e2112396aa77c47cd5d21a8b2f
• use cast create2 -s 0x112233 to get a salt so deployed addr starts w/ 0x112233. full addr is 0x112233C73c74a810BA963171ADc431A60e051D38
• for full verification, we include metadata downside is ClaimHelp.sol file must be kept exactly the same (even extra space will change code hash)
• operation overhead is to call claim(address router) for supported routers
• note forge script script/create2_claimer.sol ... --verify failed due to possibly an etherscan bug. Run forge verify-contract 0x112233C73c74a810BA963171ADc431A60e051D38 ClaimHelp --chain sepolia separately successfully verifies contract

High level design

Flow

1. projects submit list of tx hashes to brevis unirebate server and get a request id
2. server will fetch tx receipts, organize events by poolids and start proving process (ineligible pools are ignored)
3. server submits to Brevis gateway, polling till onchain calldata available and save to db
4. projects polling server for calldata and send onchain tx to their own router contract

Sepolia setup

• this repo, deploy uni/eth price oracle, UniEthTestnet has ratio in constructor
• brevis-network/uniswap-v4-core repo mysetup branch, deploy myswaprouter and two erc20s. Note smaller addr token will be currency0.
• brevis-network/uniswap-v4-template repo my branch, set script/base/Constants.sol POOLMANAGER and posm from uniswap doc, Config.sol token0 and token1 from previous step
• run 00_Counter to deploy counter hook by CREATE2, then add hook address to Config.sol. CREATE2 due to uniswap requires hook addr to have certain bits set, only possible by mining salt with create2.
• run 01_CreatePoolAndMintLiquidity, initialize pool w/ our erc20 tokens and add liquidity
• 03_Swap: set myswaprouter address and modify swap amount, then run script

now we have swap event and slot available at same block. next to setup zk related, prove and verify onchain

onchain:

• this repo, deploy zkrebate and transfer test uni to zkrebate contract
• run add_pool, make sure PoolKey matches 01_CreatePoolAndMintLiquidity, query map to check poolid matches
• add zkrebate addr to allowed provers. call BrevisProof.addProvers (can use etherscan web, must be owner)

offchain:

• server must listen to pool Initialize event from 01_CreatePoolAndMintLiquidity blocknumber and populate db
• send swap tx to server which starts the process and sent to prover
• prover generates app proof and submits to Brevis Gateway

when proof is ready, run claim.sol submit onchain to myswaprouter:

Contract	Address
Oracle	0xc8caf3c1d76d264b6d5d511d883b58b3874eafa0
MySwapRouter	0xd45f72e31e19fcf75bF47d217e500745Cb36263b
Hook	0xaA5f84D2F6A2423E50b3e598F934f6626e12CAc0
ZkRebate	0xA50e5203ECa1685B4e01A8A569dd12150A8b419D