Slippage

Slippage is what happens between your quote and your settlement. An AMM quote is computed from pool reserves at one instant, but the ledger keeps moving: if other swaps settle against the same pool before yours does, the reserves your trade actually meets differ from the ones that priced your quote. The resulting difference in your executed rate is slippage.

It is worth separating from price impact. Price impact is the deterministic cost of your own trade's size, fully visible in the quote. Slippage is the nondeterministic part, caused by other people's activity in the gap before settlement. Impact you can calculate; slippage you can only bound.

The standard defense is a slippage tolerance: a worst acceptable rate attached to your transaction. If settlement would cross that bound, the transaction fails instead of filling badly, and an atomic ledger like Canton returns your assets untouched. Set the tolerance too tight and normal reserve movement fails your trades; too loose and you accept meaningful drift.

In quiet pools the practical slippage on OneSwap is often near zero simply because few trades compete for the same reserves, but the protection matters most exactly when activity spikes.