🚧 UNDER CONSTRUCTION 🚧

Router Rebates

A gas subsidy program, sponsored by Uniswap Foundation and Brevis, to encourage routing and solving integration with Uniswap v4 Hooks

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Program Specs

For any transaction that touches a Uniswap v4 pool, with a hook, authors of the swap router (sender address in the Swap event), will be able to claim a rebate against the gas spent

Rebates will be available on the 12 initial chains with Uniswap v4, with claims faciliated on Unichain. The rebate is paid out in native Ether.

Rebate Size

For a given transaction hash, with swap events coming from a hook'ed pool, the rebate is calculated according to:

gasUsageToRebate = 80,000 * number_of_swap_events + 80,000
ethToRebate = gasUsageToRebate * txnReceipt.baseFee

As a safety precaution against hyper-optimized swaps, the minimum of the above calculation or 80% of transaction gas usage is taken

Router Integrations

Because rebates are claimed on Unichain for trades happening on other networks, beneficiaries need to specify the authorized claimer.

The swap router contract (the contract calling poolManager.swap()) should implement this function selector:

function rebateClaimer() external view returns (address);

See IRebateClaimer for the full interface.

The wallet which claims the rebate is specified by this address, rebateClaimer. The backend system performs verification against this address, to prevent griefing scenarios where malicious attackers are claiming rebates they are not entitled to.

Claim Process: Signatures

The Router Rebates initiative offers two flows for claiming rebates. In the signature flow, an API service operated by Uniswap Foundation, verifies transactions to produce the rebate size and an authorization signature. The authorization signature, along with its corresponding data, is provided to a smart contract on Unichain to claim the rebate.

To prevent signature replays and/or duplicate claiming, rebate claims operate on a block range. Once a block number has been claimed against, transactions occuring prior to the block number are inelligible for rebates.

1. Gather a list of transaction hashes, for a single chain

txnHashList = ["", ""]

2. Provide the chainId and transaction list to the API

curl -G 'http:/localhost:3000/sign' --data-urlencode 'chainId=1' --data-urlencode 'txnHashes=0x77014b4caad9c07a4840d6874d6f219ec3476c0311c90036e5f2e4c8072396f6,0xa2b356e88e7b8a2992711790e57a4c0dba7d409d97ea19cd42102f39dbddc3c9'

3. Claim the rebate, from the authorized claimer address, on Unichain

IRouterRebates(routerRebateAddress).claimWithSignature(...);

Glossary

swap router / beneficiary - the onchain contract, that implements IUnlockCallback, and is the caller for poolManager.swap(). Can also be thought of as the sender address in the Swap() event

claimer - the address which is claiming the rebate on behalf of the swap router / beneficiary

recipient - the recipient address that is receiving the rebate

Claim with Brevis ZK Proof

1. router contract emits event Claimer(address) to indicate which address is authorized to call claim function
2. router project sends list of tx to Brevis backend zk/new?chainId=1&txnHashes=0x123...,0x456..., and receives reqid in response
3. router project queries zk/get/{reqid} to get proof data. Claimer then sends onchain tx to claimWithZkProof