Shadow Arena #001: Basin

Basin is a composable DEX architecture built by Beanstalk Farms. It decouples the AMM into pluggable components: Wells (liquidity pools), Well Functions (pricing invariants), Pumps (oracles), and Aquifers (factories). The core ConstantProduct2 implements x * y = k, the same CFAMM as Uniswap V2.

Scope (1145 SLOC)

File	SLOC	Description
src/Well.sol	486	Core AMM pool: swap, liquidity, LP token, pump updates
src/pumps/MultiFlowPump.sol	231	Oracle: geometric EMA + cumulative geometric SMA
src/Aquifer.sol	58	Permissionless Well factory and registry
src/functions/ConstantProduct2.sol	47	x * y = k pricing invariant for 2 tokens
src/functions/ProportionalLPToken2.sol	14	Proportional LP token math for 2 tokens
src/libraries/LibLastReserveBytes.sol	92	Byte packing for pump reserve storage
src/libraries/LibBytes.sol	73	Byte packing for uint128 reserves
src/libraries/LibBytes16.sol	58	Byte packing for bytes16 pump values
src/libraries/LibWellConstructor.sol	57	Well construction and encoding helpers
src/libraries/LibContractInfo.sol	29	Contract info retrieval utilities

Documentation

Source Code Protocol Docs

Part of the Uniswap V2 Path

This shadow audit connects to the Uniswap V2 Build module. Students who completed the CFAMM build have an advantage because they understand the core architecture.

View Build Module

Duration7 days

Total Findings14

Scope1145 SLOC

PriceFree