yswap impermanent loss protection on buy/sell

[sirpy]

How does yswap protect if the protection only happens on withdrawing liquidity and not during every buy/sell?

audit/contracts/ySwap/StableAMMv3.sol

Line 473 in 4b07283

uint valueA = Oracle(link).getPriceUSD(underlying).mul(amountA).div(uint256(10)**ERC20Detailed(token).decimals());

[sirpy]

@andrecronje
can you explain why yswap protect from impermanent loss?
it needs to know how much of asset A i deposited originally, to compare their value today vs the value I get when withdrawing my LP.
In the code I see only calculation of using current amount of asset A i'm entitled too from the pool, but if asset A relative amount in the pool has shrunk (because of drainage by arbitragers), it will not correctly calculate impermanent loss