Tx Preview

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://api.solsentry.app/x402/v1/tx-preview' \
  -H 'content-type: application/json' \
  --data-raw '{"parsed_tx":{"accounts":[],"instructions":[]}}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://api.solsentry.app/x402/v1/tx-preview' \
  -H 'content-type: application/json' \
  --data-raw '{"parsed_tx":{"accounts":[],"instructions":[]}}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/svm @solana/kit @scure/base
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactSvmScheme } from "@x402/svm/exact/client";
import { createKeyPairSignerFromBytes } from "@solana/kit";
import { base58 } from "@scure/base";

// Pays at most $0.008 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.008" });
registerExactSvmScheme(client, { signer: await createKeyPairSignerFromBytes(base58.decode(process.env.SVM_PRIVATE_KEY)) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.008 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.solsentry.app%2Fx402%2Fv1%2Ftx-preview&method=POST
const res = await pay("https://api.solsentry.app/x402/v1/tx-preview", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "parsed_tx": {
      "accounts": [],
      "instructions": []
    }
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,svm]"
import os
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.svm import KeypairSigner
from x402.mechanisms.svm.exact.register import register_exact_svm_client

# Pays at most $0.008 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.008"})
register_exact_svm_client(client, KeypairSigner.from_base58(os.environ["SVM_PRIVATE_KEY"]))

with x402_requests(client) as session:
    res = session.post(
        "https://api.solsentry.app/x402/v1/tx-preview",
        json={
            "parsed_tx": {
                "accounts": [],
                "instructions": [],
            },
        },
    )
    print(res.status_code, res.text)