Swap on CPMM - Powfi Docs

1. Load and fetch the pool

import { Powfi, CpmmModule, PoolNotFoundError } from '@alephium/powfi-sdk'
import { ALPH_TOKEN_ID } from '@alephium/web3'

const powfi = Powfi.load({ networkId: 'mainnet', signer })
const tokenIn = ALPH_TOKEN_ID
const tokenOut = '<token id>'

let pool
try {
  pool = await powfi.cpmm.getPoolState(tokenIn, tokenOut)
} catch (e) {
  if (e instanceof PoolNotFoundError) throw new Error('No CPMM pool for this pair')
  throw e
}

2. Quote (offline)

Exact in
Exact out

const quote = CpmmModule.computeSwapAmount({
  state: pool,
  tokenInId: tokenIn,
  tokenOutId: tokenOut,
  amountIn: 5n * 10n ** 18n, // sell exactly 5 ALPH
  slippageBps: 50n
})

quote.tokenOutAmount        // expected output
quote.minimalTokenOutAmount // guaranteed minimum
quote.priceImpact           // percent

const quote = CpmmModule.computeSwapAmount({
  state: pool,
  tokenInId: tokenIn,
  tokenOutId: tokenOut,
  amountOut: 100n * 10n ** 6n, // buy exactly 100 units of a 6-decimal token
  slippageBps: 50n
})

quote.tokenInAmount        // expected input
quote.maximalTokenInAmount // worst-case input

Show the execution price from raw amounts and decimals:

import Decimal from 'decimal.js'
import { NumericUtils } from '@alephium/powfi-sdk'

const inHuman = NumericUtils.scaleDecimal(quote.tokenInAmount, quote.tokenInInfo.decimals)
const outHuman = NumericUtils.scaleDecimal(quote.tokenOutAmount, quote.tokenOutInfo.decimals)
const price = outHuman.div(inHuman) // tokenOut per tokenIn

3. Execute

const { address } = await signer.getSelectedAccount()

// Optional: pre-check balances to fail fast with a readable error
const bal = await powfi.nodeProvider.addresses.getAddressesAddressBalance(address)
const balances = new Map<string, bigint>([[ALPH_TOKEN_ID, BigInt(bal.balance)]])
for (const t of bal.tokenBalances ?? []) balances.set(t.id, BigInt(t.amount))

const result = await powfi.cpmm.swap(
  {
    tokenInId: tokenIn,
    tokenOutId: tokenOut,
    amountIn: 5n * 10n ** 18n,
    slippageBps: 50n,
    sender: address,
    ttlMinutes: 10
  },
  balances
)
console.log(result.txId)

swap re-fetches the pool state and re-quotes before signing, so the minimum it enforces is based on the state at send time, not the state you displayed.

The ALPH balance check compares against the swap input only. The transaction also needs a few DUST_AMOUNTs of ALPH for outputs, plus gas. Keep some headroom when the input token is ALPH.

4. Handle errors

Error	What to show
`PriceImpactTooHighError`	”Price impact above 5%. Reduce the amount.”
`InsufficientBalanceError`	The message already includes required and available amounts.
`InsufficientLiquidityError`	Exact-out amount exceeds the pool reserve.
Node error mentioning the router	Slippage or deadline hit. Re-quote.

Moving the price to a target

For arbitrage or rebalancing, swapTo computes the trade that moves the pool to a target price (token1 per token0 in sorted order, human units):

await powfi.cpmm.swapTo({ tokenA: tokenIn, tokenB: tokenOut, targetPrice: 0.052, sender: address, slippageBps: 30n })

swapTo skips the 5% price-impact guard.