The launch position is one-sided. At the opening price it holds the new token and none of the quote. No USDC, ETH, or stock is deposited to buy the token. That is how a launch can cost nothing: the creator does not have to fund a $5,000 bid.

The first buy is what puts quote into the pool. The price moves up off the open, along the curve in Price. A later sell can take that quote back out. It can walk the price down to the opening price, and no further through the launch position. When the price is back on the open, the position is tokens again, and the pool will not buy any more.

How much of a sell fills

You can sell up to the quote buyers have put in, minus what earlier sellers have already taken. A market order larger than that does not invent a bid. The part that fits is sold. The rest stays in the wallet. The trade panel leaves “You receive” blank when the full amount does not fit, instead of sending a transaction that only moves a scrap.

A buy on this site

The router swaps through the launch pool and sends the tokens to your wallet. That delivery is what the indexer records as your cost. The cost is the quote that went through the official pool, after the pool fee.

A direct Uniswap buy pays the pool fee, because the fee is part of the pool. The tokens arrive from Uniswap’s router, so your entry price is not recorded and a later Zero-G Rebate has nothing to pay against.