Rakurai Reward Distribution Program

A Solana smart contract for distributing block rewards among Rakurai, validators, and stakers. Rewards are accumulated throughout each epoch and distributed post-epoch to stakers using a Merkle tree-based mechanism.

➤ For more details, refer to the IDL File.

How It Works

Each validator, for each epoch, creates a unique PDA called RewardCollectionAccount:

• Seeds: ["REWARD_COLLECTION_ACCOUNT", validator_vote_pubkey, epoch_number]
• Only the validator's authorized withdrawer can initialize it.
• When creating the account, the validator must specify:
  • reward_merkle_root_authority — Authority responsible for uploading the Merkle root post-epoch.
  • validator_commission_bps — Commission (in basis points) that the validator retains from block rewards.
  • rakurai_commission_bps — Commission (in basis points) for Rakurai from block rewards.
  • rakurai_commission_account — Destination account for Rakurai's commission.

The values for rakurai_commission_bps, validator_commission_bps, and rakurai_commission_account are pulled from the RakuraiActivationAccount, a validator-specific PDA (not epoch-specific), part of the rakurai_activation program. This account controls whether the validator is running the Rakurai scheduler (and should be charged commission).

🔁 Epoch Flow

1. RewardCollectionAccount Account Initialization

On the first turn of each epoch, the RewardCollectionAccount is automatically initialized by the Rakurai Solana client. This initialization includes:

• Commission details (from validator-specific RakuraiActivationAccount).
• Authority to update the reward Merkle root (only this authority can upload the Merkle root to the RewardCollectionAccount account).

Account initialization logic is part of the Rakurai Solana client. The node operator must specify the following CLI arguments.

2. Per-Turn Transfers

During every leader turn:

• The previous turn's block reward is processed:
  • Rakurai commission → transferred to Rakurai's account.
  • Validator commission → remains in the validator's identity account.
  • Staker share → accumulated into the RewardCollectionAccount.

Because the reward of the current turn is transferred during the next one, the first turn of an epoch handles the last reward of the previous epoch.

3. Post-Epoch Staker Distribution

At the final slot of each epoch, the following process takes place:

• A snapshot of Solana accounts is captured.
• Each validator's staker details and stake weights are extracted.
• An off-chain Merkle tree is generated containing reward share data.
  • Extra flexibility: At this stage, specific stakers can be blacklisted, and individual stake weights can be adjusted before finalizing the tree.
• The Merkle root is uploaded to the RewardCollectionAccount by the reward_merkle_root_authority.
• Each staker claims their rewards by submitting a valid Merkle proof derived from the Merkle root. Claims are processed individually per staker.

Reward Distribution — Free & Automated by Rakurai

• Set this authority to Rakurai for fully automated reward distribution.
• Keep it yourself if you want to do the distribution yourself.

When set to Rakurai, the rakurai will automatically:

1. Create a snapshot
2. Calculate the Merkle root
3. Upload it on-chain
4. Distribute rewards to stakers

0% distribution fees charged by Rakurai — only standard Solana transaction fees apply.

Account Lifecycle

• RewardCollectionAccount is valid for 10 epochs.
• After that:
  • Any unclaimed funds are returned to the validator's identity account.
  • The account is closed to reclaim rent.