Buying and selling

Fees, previews, slippage, refunds, approvals.

Fees

1% of the ETH side of every curve trade, buy or sell. Half accrues to the star, half to the protocol. The fee is carved out of the ETH you send (buy) or the ETH you receive (sell); the preview shows it as its own line. After graduation the pool's own 1% LP fee applies instead, and it accrues to the locked position, which is split the same way when collected.

What you see is what executes

On the curve, the site recomputes the contract's arithmetic locally, integer for integer, so the preview is the quote. After graduation there is no closed form: the site simulates the exact call it is about to send (eth_call of buy or sell) and shows the result.

Slippage

Every trade carries a minimum output of the preview minus 1%. If the chain moved against you by more than that between preview and inclusion, the transaction reverts and you keep your funds. On the curve this practically never triggers unless someone trades the same token in the same 100 ms block.

The buy that graduates

If your buy would take more than what is left on the curve, it is filled to the last token, the fee is charged only on what was spent, and the rest of your ETH comes straight back in the same transaction. That transaction also opens the pool; the preview says so before you sign.

Approvals

Buying needs no approval: you send ETH. The first sell of a token needs an ERC20 approval to the launchpad. The site asks for an unlimited approval once, keeps your amount in the form, and flips the button to Sell when the approval confirms.