# ReputationFee

> Charges a counterparty according to how it has behaved, using an on-chain reputation registry, with no signature to present and nothing for a router to forward.

A production Uniswap v4 hook. Source: https://github.com/nirholas/reputation-fee. Part of the HookForge catalogue: https://hookforge.pages.dev

## 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. An agent registers the router it trades through, once, in a transaction sent from its own address:   reputationFee.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.

## Prior art
Identity-gated hooks are common (KYC, Civic, VioletID, World ID, PureFi) and they gate: pass or be refused. Loyalty and fidelity hooks discount by volume or tenure, which is a proxy for behaviour rather than a judgement of it. Pricing continuously off an external reputation score, and resolving the trader through a registered router so no signature or hookData is needed, is the contribution here.

## Where it does not help
The pool trusts the registry absolutely: a registry that can be bought is a fee schedule that can be bought, and nothing here detects that. Registration is also per router, so an agent that trades through a router it has not registered pays the unknown rate until it registers, and an agent using a shared public router either cannot register it or is subsidising everyone else who uses it.

## Facts
Slug: reputation-fee
Contract: ReputationFeeHook
Callbacks: beforeSwap, afterInitialize
Parameters: minFee (uint24), maxFee (uint24)
Dynamic fee required: yes

## Caveats
- Unaudited.
- A deployment with status "deterministic" is a mined CREATE2 address with no code at it yet. Never present one as live.