Liquidity Management

The Mento SDK v3 lets you add liquidity, remove liquidity, and zap in/out for FPMM pools. You get transaction parameters to send with any viem wallet client.

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Create the client

import { Mento, ChainId, deadlineFromMinutes } from '@mento-protocol/mento-sdk'
import { parseUnits } from 'viem'

const mento = await Mento.create(ChainId.CELO)

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Add liquidity (two tokens)

Add both sides of a pool in the desired ratio. You need the pool address, token addresses, amounts, recipient, and owner:

const addTx = await mento.liquidity.buildAddLiquidityTransaction(
  poolAddress,
  tokenA,
  amountA,
  tokenB,
  amountB,
  recipient,
  owner,
  { slippageTolerance: 0.5, deadline: deadlineFromMinutes(5) }
)

Send the returned transaction(s) with your viem wallet (approval first if present, then the add-liquidity tx).

---

Zap in (single token → LP)

Deposit a single token and the SDK splits it into the two pool assets according to a split ratio (e.g. 0.5 = 50/50):

const zapTx = await mento.liquidity.buildZapInTransaction(
  poolAddress,
  tokenIn,
  amountIn,
  0.5,   // split ratio (e.g. 50/50)
  recipient,
  owner,
  { slippageTolerance: 0.5, deadline: deadlineFromMinutes(5) }
)

Use this when users want to provide liquidity with one token only.

---

Zap out (LP → single token)

Remove liquidity and receive a single token (the other side is swapped internally). Build the transaction with the pool, LP amount, desired output token, and options:

const zapOutTx = await mento.liquidity.buildZapOutTransaction(
  poolAddress,
  lpAmount,
  tokenOut,
  recipient,
  owner,
  { slippageTolerance: 0.5, deadline: deadlineFromMinutes(5) }
)

---

Remove liquidity (LP → two tokens)

Standard removal: burn LP and receive both pool tokens in proportion to the pool’s reserves. Use the SDK’s remove-liquidity builder (method name may be buildRemoveLiquidityTransaction or similar—check the package exports) with pool address, LP amount, recipient, owner, and slippage/deadline.

---

LP token balance

Read a user’s LP token balance for a given pool:

const balance = await mento.liquidity.getLPTokenBalance(poolAddress, owner)

Use this to show users their position size or to build remove/zap-out amounts.

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Summary

Operation	Service method
Add liquidity (two tokens)	mento.liquidity.buildAddLiquidityTransaction(...)
Zap in (single token → LP)	mento.liquidity.buildZapInTransaction(...)
Zap out (LP → single token)	mento.liquidity.buildZapOutTransaction(...)
LP balance	mento.liquidity.getLPTokenBalance(poolAddress, owner)

All builders return transaction params (and optional approval) for you to send with a viem wallet. Use slippage tolerance and deadline to protect users. Runnable examples: mento-sdk-examples.