> ## Documentation Index
> Fetch the complete documentation index at: https://docs.meteora.ag/llms.txt
> Use this file to discover all available pages before exploring further.

# Farming Rewards

> How DAMM v2's built-in farming works — reward slots, pro-rata distribution, initializing rewards, funding, and claiming. No separate staking contract needed.

## 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.

***

## 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])
```

| Field                     | Description                                                        |
| ------------------------- | ------------------------------------------------------------------ |
| `reward_per_token_stored` | Cumulative rewards per unit liquidity (U256, stored as `[u8; 32]`) |
| `reward_rate`             | Tokens emitted per second (or slot)                                |
| `reward_duration_end`     | When the current campaign ends                                     |
| `total_claimed_rewards`   | Lifetime claimed by this position                                  |

### Why U256?

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

***

## Lifecycle

### 1. Initialize a Reward

The pool creator calls `initializeReward` to set up one of the two reward slots:

```typescript theme={"system"}
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 between 86400 seconds (1 day) and 31536000 seconds (1 year) (`InvalidRewardDuration`)
* Cannot re-initialize an already active slot (`RewardInitialized`)

**Event emitted:** `EvtInitializeReward`

***

### 2. Fund the Reward

Transfer reward tokens into the reward vault:

```typescript theme={"system"}
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`

***

### 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
```

***

### 4. Claim Rewards

```typescript theme={"system"}
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`

***

## Updating a Reward Campaign

| Action              | Instruction                | Notes                                                        |
| ------------------- | -------------------------- | ------------------------------------------------------------ |
| Change duration     | `updateRewardDuration`     | Can only extend, not shorten an active campaign              |
| Change funder       | `updateRewardFunder`       | New funder becomes responsible for future `fundReward` calls |
| Withdraw ineligible | `withdrawIneligibleReward` | Reclaim tokens after campaign ends with unfunded remainder   |

***

## Reward Constraints

| Constraint                     | Details                                                                       |
| ------------------------------ | ----------------------------------------------------------------------------- |
| Max reward slots               | 2 per pool                                                                    |
| Reward during locked liquidity | ✅ Vested + permanent locked liquidity earns rewards                           |
| Token 2022 rewards             | ✅ Supported                                                                   |
| Native SOL rewards             | ❌ (use wrapped SOL)                                                           |
| Frozen vault                   | If reward vault is frozen, must skip reward (`RewardVaultFrozenSkipRequired`) |

***

## Reading Pending Rewards (TypeScript)

```typescript theme={"system"}
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());
  }
}
```