Buying and selling
Fees, previews, slippage, approvals.
Fees
The pool's own 1% fee, charged on the input of every swap: out of the ETH you send when you buy, out of the tokens you send when you sell. The launcher adds nothing on top. The fee accrues to the position rather than being paid out per trade; anyone can call collectPoolFees(token), which harvests what the position has earned and splits it between the star and the treasury. Half goes to the star at the current setting. Balances are pulled with claim(), never pushed.
What you see is what executes
Each token has exactly one position, no hook, and a price that can never leave that position's range, so a single step of Uniswap's swap maths is the whole trade. The site recomputes that step locally — the same integers with the same rounding — so the preview is the quote. It has been checked against the live pool: same inputs, same outputs, to the wei.
Slippage
buy and sell both take a minimum output, and the contract reverts if the swap comes back under it. The site sets that minimum to the preview minus 1%. If someone trades the same token between your preview and your inclusion and moves it further than that, the transaction reverts and you keep your funds.
Approvals
Buying needs no approval: you send ETH. The first sell of a token needs an ERC20 approval to the launcher, which pulls the tokens before swapping them. The site asks for it once, keeps your amount in the form, and flips the button to Sell when the approval confirms.