# GridLadder

> A pool that quotes a bid and an ask, like a market maker, instead of one price both ways.

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

## How it works
Every AMM curve has a single price at any moment, and both sides of the market trade against it. That is the defining simplification of the design, and it means a pool cannot express the one thing a quoting desk exists to express: I will buy at this, and sell at that, and the gap between them is what I am paid. The gap is not the same thing as a fee. A fee is symmetric and proportional; a spread is a position. A desk that is long and wants to get flat quotes a keen bid and a wide ask, and it does that by moving the two sides independently. An AMM with a fee cannot say that at all: raising the fee makes it less willing to trade in both directions equally, which is exactly not what the desk wanted. This pool holds two ladders. The bid ladder is what it pays for currency0, the ask ladder is what it charges, and each has its own base price, its own increment and its own band width. Set them symmetrically and it behaves like an ordinary stepped pool with a spread. Set them apart and the pool leans: keen on one side, wide on the other, which is a resting position rather than a fee schedule. Both ladders step with inventory, so the pool also becomes less willing to keep going the way it is already leaning, which is the same self-correction any inventory-aware desk applies. The spread is the providers' revenue and it never leaves the reserves, so there is no separate fee parameter: a swap that crosses the spread simply hands the pool more than the mid, and the shares are a claim on reserves that grew. Setting `askBaseX96` equal to `bidBaseX96` makes the pool free to trade and is allowed, because refusing it would be an opinion rather than a safety property.

## Prior art
Bancor's Carbon quotes independent, asymmetric bid and ask curves and is the direct ancestor of this idea, off v4 and as per-user strategies rather than a pool. Uniswap v4's own range orders express one side at a time. A single fungible v4 pool that quotes two independent inventory-stepped ladders, so providers share one book with a real spread, is the contribution here.

## Where it does not help
Two ladders mean the pool is not a conservative curve: there is no single invariant a swap preserves, so the usual arbitrage-free reasoning about constant-function market makers does not apply, and a badly configured spread can be crossed for a loss. The bands are also fixed at deployment, so a pool whose asset leaves the configured range stops quoting on that side. It is a market maker's tool and it wants a market maker's attention.

## Facts
Slug: grid-ladder
Contract: GridLadderHook
Callbacks: none
Parameters: none
Dynamic fee required: no

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