ReputationFee

How it works

Pools price everyone identically because they cannot tell anyone apart, and the cost of that falls on the people who are cheapest to trade with. A venue that could distinguish its flow would quote the retail order and the arbitrageur differently, which is what every venue that can identify its counterparties actually does. The obstacle in v4 is that a hook does not see the trader.

`beforeSwap` receives the router, not the person who called it, so any scheme keyed on the trader's address needs the trader to sign something and the router to forward it, which means most routers cannot trade the pool at all. This takes the other route. register(myRouter); Thereafter the hook resolves `sender` to that agent with one storage read, asks the registry for its score, and prices the swap between `maxFee` at a score of zero and `minFee` at a perfect score.

No signature, no `hookData`, nothing for a router to support. Flow through an unregistered router is simply unknown and pays `maxFee`, which is the correct default: an unidentified counterparty is priced as the worst one. Spoofing is not possible because the mapping runs from router to agent and only the agent can write its own entry.

Registering a router somebody else also uses means paying for their flow with your reputation, which is a mistake you can only make about yourself. The registry is fixed at deployment and the fee bounds are fixed before the pool exists. There is no admin and no way to re-point the pool at a friendlier scorer once liquidity has arrived.

Using it

Uniswap v4 removed hookData from initialize, so per-pool parameters arrive out of band. Fix them for a pool key whose pool does not exist yet, then initialize. Nobody can change them afterwards, including you.

hook.configure(
    key,
    ReputationFeeHook.Config({
        minFee: /* uint24 */ 0,
        maxFee: /* uint24 */ 0
    })
);

poolManager.initialize(key, startingSqrtPriceX96);

The pool's fee field must be LPFeeLibrary.DYNAMIC_FEE_FLAG. The hook rejects a pool initialized without it, which is the most common integration failure.

Parameters

From TypeScript

npm i @hookforge/sdk

import {getHook, hookAddress, poolKeyFor} from "@hookforge/sdk";

const hook = getHook("reputation-fee");
const key  = poolKeyFor({
  hook: hookAddress("reputation-fee", 8453),   // Base
  currencyA: USDC, currencyB: WETH,
  tickSpacing: 60, dynamicFee: true,
});

What it reverts with

The callbacks it claims

Uniswap v4 reads a hook's permissions from the low fourteen bits of its own address, which is why deploying one means mining a CREATE2 salt. This hook claims 2, so every deployment of it has an address ending in 0x1080.

• beforeInitialize
• afterInitialize
• beforeAddLiquidity
• afterAddLiquidity
• beforeRemoveLiquidity
• afterRemoveLiquidity
• beforeSwap
• afterSwap
• beforeDonate
• afterDonate
• beforeSwapReturnsDelta
• afterSwapReturnsDelta
• afterAddLiquidityReturnsDelta
• afterRemoveLiquidityReturnsDelta

It says what it is, on-chain

Nothing about a hook's address tells an indexer, a wallet, a router or an agent what the pool does, which is why hook discovery today is a curated list. This hook answers for itself, in one eth_call, with no registry in the loop.

cast call $HOOK "hookName()(string)"    # ReputationFee
cast call $HOOK "specURI()(string)"     # https://reputation-fee.pages.dev/hook.json
cast call $HOOK "hookTags()(string[])"  # agent, reputation, dynamic-fee, erc8004, no-admin

Build, test and deploy

git clone --recurse-submodules https://github.com/nirholas/reputation-fee
cd reputation-fee
forge build && forge test

# Dry run: mines the salt, prints the address, sends nothing.
forge script script/Deploy.s.sol --rpc-url $RPC_URL

# For real.
forge script script/Deploy.s.sol --rpc-url $RPC_URL --broadcast --verify

Try it

This is the hook running, not a picture of it. Connect a wallet on a chain it is deployed to, or bring the whole stack up locally in one command and use it with no funds and no wallet risk at all.

git clone --recurse-submodules https://github.com/nirholas/reputation-fee
cd reputation-fee

anvil &
forge script script/DeployLocal.s.sol --rpc-url http://127.0.0.1:8545 --broadcast \
  --private-key 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

node web/build.mjs && npx serve web/dist