swap

Before Starting Work Critical - Ask these from user

MANDATORY — Do NOT write or modify any code until every item below is answered by the user:

• RPC URL provided or a fallback agreed upon (for any on-chain or tx-building step)
• Signer wallet public key (fee payer / user)
• Framework confirmed (Next.js, Express, CLI scripts only, other)
• Operation type confirmed (buy or sell)
• Coin mint address provided
• Amount confirmed (SOL lamports for buy; token smallest units for sell)
• Front-runner protection desired? If yes, confirm tip amount (default 0.0001 SOL). Transactions will be sent only to Jito block engine endpoints.

You MUST ask the user for ALL unchecked items in your very first response. Do not assume defaults. Do not proceed until the user has explicitly answered each one.

API (preferred) — https://fun-block.pump.fun

Use the API to build swap transactions instead of running scripts directly. The API automatically determines coin state (bonding curve vs AMM) and builds the correct transaction.

POST /agents/swap

Builds a buy or sell transaction. Set inputMint to So11111111111111111111111111111111111111112 (NATIVE_MINT) for buys, or set outputMint to NATIVE_MINT for sells.

Request body:

{
  "inputMint": "So11111111111111111111111111111111111111112",
  "outputMint": "<TOKEN_MINT>",
  "amount": "1000000",
  "user": "<PUBKEY>",
  "slippagePct": 2,
  "feePayer": "<PUBKEY>",
  "frontRunningProtection": false,
  "tipAmount": 0,
  "encoding": "base64"
}

Only inputMint, outputMint, amount, and user are required. All other fields have defaults.

tipAmount is a Jito tip in SOL (e.g. 0.0001 for 100,000 lamports). Only relevant when frontRunningProtection is true.

Encoding: The API defaults to "base58" encoding. Always pass "encoding": "base64" in the request body — scripts already output base64. When sending the signed transaction to an RPC or Jito endpoint, the encoding used to serialize the transaction must match the encoding parameter passed in the send call. Mismatched encodings will cause transaction failures. Always explicitly pass encoding: "base64" in sendTransaction / simulateTransaction RPC calls — never rely on the RPC's default.