Reward Manager

1. Biweekly Reward Cycle

The Curvance Protocol operates on a biweekly (2-week) epoch cycle for distributing rewards to veCVE holders across all supported chains. This process is coordinated by the MessagingHub contract which serves as the cross-chain communication layer.

Key aspects:

• Each epoch lasts exactly 2 weeks as defined by EPOCH_DURATION in the CentralRegistry

• The MessagingHub coordinates epoch transitions by querying veCVE points across all chains

• The RewardManager tracks which epoch's rewards have been delivered using nextEpochToDeliver

• State transitions occur when the MessagingHub calls recordEpochRewards() with the calculated reward amounts

State machine:

2. Pro-Rata Distribution

Rewards are distributed proportionally across all chains based on the amount of veCVE locked on each chain.

Key aspects:

• The MessagingHub uses Wormhole's Cross-Chain Query (CCQ) to get accurate veCVE point counts from all chains

• Reward distribution is calculated as: (Chain's veCVE Points / Total veCVE Points) * Total Rewards

• Each chain receives a pro-rata share of the total protocol fees based on its proportion of total locked veCVE

• This creates an incentive for chains to attract veCVE lockers to increase their share of rewards

Data flow:

3. Reward Accumulation

The system allows users to accumulate rewards over multiple epochs without having to claim them immediately.

Key aspects:

• Each user has a userNextClaimIndex that tracks the next epoch they can claim rewards from

• epochRewardsPerPoint records the rewards allocated per veCVE point for each epoch

• Users can claim multiple epochs of accumulated rewards in a single transaction

• The formula for a user's rewards for an epoch is: (User's veCVE Points * epochRewardsPerPoint[epoch]) / WAD

4. USDC Distribution via CCTP/Wormhole

The cross-chain movement of rewards (primarily USDC) is handled through Circle's Cross-Chain Transfer Protocol (CCTP) and Wormhole's messaging system.

Key aspects:

• The protocol uses CCTP to transfer USDC between chains, ensuring secure token transfers

• Wormhole's automatic relayer system delivers cross-chain messages with execution guarantees

• The MessagingHub sends both USDC tokens via CCTP and reward metadata via Wormhole

• When a chain receives USDC, it routes the tokens to its local RewardManager

Cross-chain token flow:

This architecture ensures that rewards are efficiently distributed across chains while maintaining a consistent state of reward records throughout the entire protocol.