Quotes & swaps

Quotes and Swaps

This guide shows how to get price quotes and execute swaps using the unified SDK (@whetstone-research/doppler-sdk-alpha) across Uniswap V2, V3, and V4 (including Doppler dynamic auctions).

• Quoting uses the SDK Quoter for V2/V3/V4.

• Executing swaps uses the Uniswap Universal Router. For convenience, we show examples with the doppler-router helpers used in the demo app.

Setup

import { DopplerSDK, Quoter, getAddresses, DYNAMIC_FEE_FLAG } from '@whetstone-research/doppler-sdk'
import { createPublicClient, createWalletClient, http, parseUnits } from 'viem'
import { base } from 'viem/chains'

const publicClient = createPublicClient({ chain: base, transport: http(rpcUrl) })
const walletClient  = createWalletClient({ chain: base, transport: http(rpcUrl), account })

const sdk = new DopplerSDK({ publicClient, walletClient, chainId: base.id })
const quoter = new Quoter(publicClient, base.id)
const addresses = getAddresses(base.id)

---

Quoting

V3: Exact Input (Single Pool)

const { amountOut, sqrtPriceX96After } = await quoter.quoteExactInputV3({
  tokenIn:  tokenInAddress,
  tokenOut: tokenOutAddress,
  amountIn: parseUnits('1.0', inDecimals),
  fee: 3000,                 // 0.3%
  sqrtPriceLimitX96: 0n,     // optional
})

V3: Exact Output (Single Pool)

const { amountIn } = await quoter.quoteExactOutputV3({
  tokenIn:  tokenInAddress,
  tokenOut: tokenOutAddress,
  amountOut: parseUnits('100', outDecimals),
  fee: 3000,
})

V2: Exact Input (Path)

// Simple 2-hop path (tokenIn -> tokenOut). Multi-hop supported.
const amounts = await quoter.quoteExactInputV2({
  amountIn: parseUnits('1.0', inDecimals),
  path: [tokenInAddress, tokenOutAddress],
})
const amountOut = amounts[amounts.length - 1]

V4 (Dynamic Auctions): Exact Input

For Doppler V4 dynamic auctions, build a poolKey and determine direction with zeroForOne:

import { Address } from 'viem'

// Sort to get currency0/currency1 as in V4 (lexicographically ascending)
const [currency0, currency1] = [baseToken as Address, quoteToken as Address]
  .sort((a, b) => (a.toLowerCase() < b.toLowerCase() ? -1 : 1))

const poolKey = {
  currency0,
  currency1,
  fee: DYNAMIC_FEE_FLAG, // Doppler dynamic auctions use the dynamic fee flag
  tickSpacing: 8,        // Typical for Doppler auctions; use actual value if known
  hooks: hookAddress as Address,
}

// Direction: swap 0->1 when tokenIn is currency0
const zeroForOne = (tokenInAddress.toLowerCase() === currency0.toLowerCase())

const { amountOut } = await quoter.quoteExactInputV4({
  poolKey,
  zeroForOne,
  exactAmount: parseUnits('1.0', inDecimals),
  hookData: '0x', // usually empty for Doppler swaps
})

Notes:

• Use your pool’s actual tickSpacing if available from the indexer or hook config.

• hookData is typically 0x for Doppler swaps.

---

Executing Swaps (Universal Router)

The SDK exposes addresses for the Uniswap Universal Router via getAddresses(chainId). To build inputs, the miniapp uses doppler-router helpers; you can do the same or craft bytes manually.

Install helpers:

npm install doppler-router

V4 Dynamic Auction: Swap Exact In Single

import { CommandBuilder, V4ActionBuilder, V4ActionType } from 'doppler-router'
import { zeroAddress, maxUint256, parseUnits } from 'viem'

// 1) Build poolKey and zeroForOne as in the quoting example
const [currency0, currency1] = [baseToken as Address, quoteToken as Address]
  .sort((a, b) => (a.toLowerCase() < b.toLowerCase() ? -1 : 1))
const poolKey = { currency0, currency1, fee: DYNAMIC_FEE_FLAG, tickSpacing: 8, hooks: hookAddress as Address }
const zeroForOne = (tokenInAddress.toLowerCase() === currency0.toLowerCase())
const amountIn = parseUnits('1.0', inDecimals)
const minAmountOut = 0n // add slippage logic as needed

// 2) Build V4 swap actions
const actionBuilder = new V4ActionBuilder()
const [actions, params] = actionBuilder
  .addSwapExactInSingle(poolKey, zeroForOne, amountIn, minAmountOut, '0x')
  // Settle and take ensures outputs are transferred correctly
  .addAction(V4ActionType.SETTLE_ALL, [zeroForOne ? poolKey.currency0 : poolKey.currency1, maxUint256])
  .addAction(V4ActionType.TAKE_ALL,   [zeroForOne ? poolKey.currency1 : poolKey.currency0, 0])
  .build()

// 3) Encode Universal Router command
const [commands, inputs] = new CommandBuilder().addV4Swap(actions, params).build()

// 4) Minimal Universal Router ABI with execute()
const universalRouterAbi = [
  {
    type: 'function',
    name: 'execute',
    stateMutability: 'payable',
    inputs: [
      { name: 'commands', type: 'bytes' },
      { name: 'inputs',   type: 'bytes[]' },
    ],
    outputs: [],
  },
] as const

// 5) Execute
const txHash = await walletClient.writeContract({
  address: addresses.universalRouter,
  abi: universalRouterAbi,
  functionName: 'execute',
  args: [commands, inputs],
  // Send ETH when swapping from native currency (currency0 usually WETH/native)
  value: zeroForOne ? amountIn : 0n,
})
const receipt = await publicClient.waitForTransactionReceipt({ hash: txHash })

Tips:

• For ERC20 inputs, ensure allowance (Permit2 or token approve). See doppler-router getPermitSignature helper.

• Use a non‑zero minAmountOut based on a prior quote and desired slippage.

V3 and V2 Swaps

The Universal Router also supports V3/V2 swaps. You can:

• Use the CommandBuilder to add V3/V2 swap commands similarly, or

• Call the respective pool routers directly (outside the scope of this doc).

The unified SDK’s Quoter covers price discovery for all of V2/V3/V4 regardless of which path you choose for execution.

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End‑to‑End Pattern (Demo application)

The doppler-demo-app demonstrates:

• Building V4 poolKey and zeroForOne from base/quote tokens

• Quoting via quoter.quoteExactInputV4

• Executing via Universal Router using doppler-router builders

• View it's code here: https://github.com/whetstoneresearch/doppler-demo-app

Look at src/pages/PoolDetails.tsx for a complete reference implementation.