Trading
The curve, then the pool. Kiln is not in the middle of either.
Trading happens on pons. Kiln does not run a router, does not take a fee and cannot see your trade. The Trade button on a coin's page opens pons.
Stage one: the bonding curve
A new coin has no pool. It trades against a formula instead: a constant-product curve with a virtual reserve on the quote side. Buying pushes the price up along the curve, selling pushes it back down. There is no counterparty and no order book.
The progress bar on every coin is how much real money has been paid into the curve against the amount pons requires before it will graduate.
Stage two: the pool
At the threshold the curve is retired and pons opens a Uniswap v4 pool with everything it collected. From then on the coin trades like any other pool coin: real depth, real slippage, a chart on DexScreener.
Fees only accrue after graduation
Curve trades do not feed the vault the way pool trades do. A coin that never graduates never burns anything.