SWAP DESK

One Rentoid is 10,000 $RENT, in both directions, always. There is no curve here and no slippage — the desk quotes the same price on the first trade and the thousandth. Buying takes a Rentoid off the shelf; selling puts one back and pays you out of the desk's $RENT. Each trade costs a flat 0.01 ETH.

The two sides are independent inventories: the shelf is what you can buy, the $RENT balance is how many sells it can absorb. Either can run out on its own — that side simply pauses until it is restocked.