Protocol

Fees and slippage

Three costs, all visible before a wallet is even connected: the Specie fee, the pool's own fee, and gas. Nothing is added on top of a quote after you see it.

The Specie fee

Rate	0.25% (25 basis points)
Taken from	the output currency, never the input
Taken by	`TAKE_PORTION`, inside the same transaction as the swap
Charged on	swaps only
Charged on transfers	nothing

Because the fee is an action in the swap itself, the amount you are shown is the amount after it. The recipient is named in the calldata of every swap, so anyone reading a transaction in the explorer can see exactly what was taken and where it went. The interface does not put that address in front of people who did not ask for it.

The pool fee

Uniswap v4 pools charge their own fee to liquidity providers, and it varies by tier. Specie quotes every tier that holds liquidity and keeps the best result for your size, then prints the winning tier's fee in the panel next to ours. That fee is not ours and we do not add to it.

Gas

Gas on Arc is paid in USDC. There is no second token to hold and no wrapped asset to keep topped up, which also means a wallet needs enough USDC to cover the amount it is spending plus the gas. When a node refuses a transaction for funds, Specie says exactly that rather than repeating the raw error.

Slippage

Slippage is your own bound on how far the pool may move between the quote and the fill. Specie offers 0.1%, 0.5%, 1% and 3%, defaults to 0.5%, and refuses anything above 5% no matter what a request asks for.

Number	Meaning
`minimums.gross`	what the pool must return before the fee, enforced on the swap action
`minimums.net`	what must reach your wallet after the fee, enforced on `TAKE_ALL`
`lossPercent`	how far your size lands under the pool's own mid, before slippage

Slippage is not price impact. Impact is what your own order does to the pool, and it is known at quote time. Slippage is what someone else's order might do before yours lands. The panel shows both, and the second one is the only one you choose.

A worked example

Spend 1,000 USDC, quoted at 920 EURC out, slippage 0.5%:

quoted out        920.000000 EURC
Specie fee        0.25%          -> 2.300000 EURC
you receive       917.700000 EURC   (shown in the panel)

gross minimum     915.400000 EURC   (920 less 0.5%)
net minimum       913.111500 EURC   (gross less the fee)

Numbers in the example are round figures for the arithmetic, not a market quote. The pool decides the rate, and the panel always shows the live one.