Staking Pool

A Solidity staking-rewards contract implementing the Synthetix StakingRewards algorithm — time-based reward distribution with O(1) accounting via rewardPerToken / earned, so per-user rewards are tracked without ever looping over stakers.

Contracts-only project (no frontend). Written to understand the canonical staking reward math from scratch, tested with Hardhat 3 + viem and deployable to Sepolia.

Contracts

Contract	What it does
staking.sol	Users stake one ERC20 and earn a second ERC20 as rewards. Reward accrual is handled by the updateReward modifier with rewardPerToken() / earned(); the owner funds rewards through notifyRewardAmount over a configurable rewardsDuration. Reentrancy-guarded.
tokenA.sol / tokenB.sol	Minimal OpenZeppelin ERC20 test tokens used as the staking / reward assets.

How the reward math works

Instead of updating every staker whenever rewards accrue, the contract maintains a single global rewardPerTokenStored accumulator. Each account snapshots it in userRewardPerTokenPaid, so a user's earnings are:

earned = balance * (rewardPerToken() - userRewardPerTokenPaid[account]) + rewards[account]

This is the standard gas-efficient staking pattern used by Synthetix and most DeFi staking pools — reward accounting stays O(1) regardless of how many users stake.

Key functions: stake · withdraw · getReward · notifyRewardAmount · setRewardsDuration Events: Staked · Withdraw · RewardPaid · RewardAdded · RewardsDurationUpdated

Development

npx hardhat test                    # run all tests
npx hardhat test solidity           # Solidity (Foundry-compatible) tests
npx hardhat test nodejs             # TypeScript integration tests (node:test + viem)

Deploy to Sepolia

Set the deployer key (kept out of the repo) via the keystore, then deploy with Ignition:

npx hardhat keystore set SEPOLIA_PRIVATE_KEY
npx hardhat ignition deploy --network sepolia ignition/modules/DeployStaking.ts

Roadmap

A multi-pool variant (MultiPool.sol — multiple staking tokens sharing one reward token, registered via addPool) is in progress on the feat/multi-pool branch.