signTransaction

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "signTransaction",
  "params": {
    "transaction": "base64EncodedTransaction"
  }
}

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "signature": "base58Signature",
    "signed_transaction": "base64EncodedTransaction",
    "signer_pubkey": "3Z1Ef7YaxK8oUMoi6exf7wYZjZKWJJsrzJXSt1c3qrDE"
  }
}

curl -X POST http://localhost:8080 \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"signTransaction","params":{"transaction":"base64EncodedTransaction"}}'

const result = await client.signTransaction({
  transaction: "base64EncodedTransaction"
});
console.log("Signature:", result.signature);
console.log("Signed tx:", result.signed_transaction);