How Staking Reward Pools Work: A Vyper Implementation Using Lazy Accounting

A developer tutorial published on DEV Community explains the mechanics behind onchain staking reward pools, arguing the underlying model is simpler than commonly perceived. The core concept is lazy accounting: instead of pushing rewards to every staker each block, the contract maintains a running index tracking how much a single staked token has accrued since inception. Each user also stores a personal checkpoint, called reward debt, to ensure they are only paid for the time they were actually staked. The guide implements this pattern in Vyper 0.4.3 using the Moccasin framework, drawing on the Unipool and Synthetix staking rewards designs. It highlights key differences from the MasterChef pattern and covers setup, contract structure, and testing practices including fuzz and integration tests.