> For the complete documentation index, see [llms.txt](https://docs.surged.fun/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.surged.fun/integration/sdk/trading.md).

# Buying and selling

The encoders return `{ to, data, value }`. Send it however you like; nothing in this package talks to the network.

## Buying

```ts
import { encodeBuy, minOutWithSlippage, previewBuy, curveStateFromApi } from '@surged/sdk'

const state = curveStateFromApi(launch)
const quote = previewBuy(state, quoteIn, { currentBlock: BigInt(head) + 1n })

const call = encodeBuy({
  pairToken: launch.pairToken,
  quoteIn,
  minTokensOut: minOutWithSlippage(quote.tokensOut, 500),
  recipient: account.address,
})

await wallet.sendTransaction({ to: launch.curve, ...call })
```

`recipient` is who receives the tokens and, just as important, **who the snipe tax is measured against**. Buying to a different address does not dodge it.

With a native quote, which is every launch today, the USDC travels as the transaction's `value`; `encodeBuy` sets it for you.

## Selling

The curve pulls the tokens from you, so it needs an allowance first. Two transactions:

```ts
import { encodeSell, launcherTokenAbi, minOutWithSlippage, previewSell } from '@surged/sdk'
import { encodeFunctionData } from 'viem'

const quote = previewSell(state, tokensIn)

await wallet.sendTransaction({
  to: launch.token,
  data: encodeFunctionData({
    abi: launcherTokenAbi,
    functionName: 'approve',
    args: [launch.curve, tokensIn],
  }),
})

await wallet.sendTransaction({
  to: launch.curve,
  ...encodeSell({
    tokensIn,
    minQuoteOut: minOutWithSlippage(quote.quoteOut, 500),
    recipient: account.address,
  }),
})
```

Wait for the approval's receipt before sending the sell. Arc has no public mempool and blocks are 500 ms, so this is fast, but a sell that arrives before its approval is mined simply reverts.

## Gas

Gas is paid in USDC, the same asset a buy spends.

* **Never spend the whole balance on a buy.** Hold back enough for the transaction.
* **Do not hardcode the reserve.** Arc's base fee floor is 20 gwei but the fee is not fixed; it reached 196 gwei on the day mainnet opened. Read the base fee of the latest block and leave headroom over it.

## Confirming

```ts
const receipt = await publicClient.waitForTransactionReceipt({ hash })
if (receipt.status !== 'success') {
  // Mined and rejected by the contract. See Handling errors.
}
```

A mined transaction is not a successful one. Check `status`; a revert still produces a receipt.


---

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