Everlong is a synthetic liquidity engine for BTC and ETH that transforms user deposits into deep, on-chain liquidity to earn sustainable, fee-based yield. By creating an internal synthetic counter-asset, Everlong deploys liquidity into AMMs without requiring users to sell or short their BTC/ETH positions. Depositors receive ERC-4626 vault tokens that accrue real yield in the asset they deposited, offering long-only exposure, institutional-scale efficiency, and DeFi composability.