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Overview

Every DAMM v2 pool has two built-in reward slots (reward_infos[0] and reward_infos[1]). Any SPL token (including Token 2022) can be used as a reward. LPs earn rewards proportional to their total position liquidity — including vested and permanently locked liquidity. No staking contract, no LP token wrapping. Positions earn rewards automatically while they hold liquidity.

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Reward Distribution Model

Rewards use a reward-per-token-stored accumulator pattern (similar to Uniswap v3 staking): 
reward_rate = total_funded_amount / reward_duration
reward_per_token += reward_rate × elapsed_time / total_pool_liquidity

pending_reward[position] = position_liquidity × (reward_per_token - checkpoint[position])
FieldDescription
reward_per_token_storedCumulative rewards per unit liquidity (U256, stored as [u8; 32])
reward_rateTokens emitted per second (or slot)
reward_duration_endWhen the current campaign ends
total_claimed_rewardsLifetime claimed by this position

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Why U256?

The accumulator uses 256-bit math to avoid overflow over long reward campaigns with small reward rates or large liquidity values.

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Lifecycle

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1. Initialize a Reward

The pool creator calls initializeReward to set up one of the two reward slots: 
const tx = await cpAmm.initializeReward({
  pool: poolAddress,
  rewardMint: rewardTokenMint,
  funder: wallet.publicKey,
  rewardIndex: 0, // 0 or 1
  rewardDuration: 30 * 24 * 3600, // 30 days in seconds
});
Constraints:
  • reward_index must be 0 or 1 (InvalidRewardIndex if out of range)
  • reward_duration must be > 0 (InvalidRewardDuration)
  • Cannot re-initialize an already active slot (RewardInitialized)
Event emitted: EvtInitializeReward

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2. Fund the Reward

Transfer reward tokens into the reward vault: 
const tx = await cpAmm.fundReward({
  pool: poolAddress,
  rewardIndex: 0,
  amount: new BN(1_000_000_000_000), // total reward budget
});
Funding sets reward_rate = amount / remaining_duration and extends the campaign if called mid-campaign. Events emitted: EvtFundReward with pre_reward_rate and post_reward_rate

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3. LPs Accrue Rewards Passively

As time passes, reward_per_token_stored increases. Every time a position is touched (add/remove liquidity, claim fees, claim reward), the position’s checkpoint is updated: 
new_reward = position_liquidity × (reward_per_token_stored - checkpoint)
pending += new_reward
checkpoint = reward_per_token_stored

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4. Claim Rewards

const tx = await cpAmm.claimReward({
  owner: wallet.publicKey,
  position: positionAddress,
  pool: poolAddress,
  rewardIndex: 0,
});
This transfers all reward_pendings[0] to the owner and resets the pending amount. Event emitted: EvtClaimReward

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Updating a Reward Campaign

ActionInstructionNotes
Change durationupdateRewardDurationCan only extend, not shorten an active campaign
Change funderupdateRewardFunderNew funder becomes responsible for future fundReward calls
Withdraw ineligiblewithdrawIneligibleRewardReclaim tokens after campaign ends with unfunded remainder

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Reward Constraints

ConstraintDetails
Max reward slots2 per pool
Reward during locked liquidity✅ Vested + permanent locked liquidity earns rewards
Token 2022 rewards✅ Supported
Native SOL rewards❌ (use wrapped SOL)
Frozen vaultIf reward vault is frozen, must skip reward (RewardVaultFrozenSkipRequired)

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Reading Pending Rewards (TypeScript)

const poolState = await cpAmm.fetchPoolState(poolAddress);
const positionState = await cpAmm.fetchPositionState(positionAddress);

// Update position reward checkpoints first (simulate on-chain update)
const currentTime = Math.floor(Date.now() / 1000);

for (let i = 0; i < 2; i++) {
  const rewardInfo = poolState.rewardInfos[i];
  if (rewardInfo.initialized) {
    const pending = positionState.rewardInfos[i].rewardPendings;
    console.log(`Reward ${i} pending:`, pending.toString());
  }
}