SDK + X402 Payment Hook

1. SDK -> /openai/v1/chat/completions               (no Authorization)
   <- 402 Payment Required
      { accepts: [{ scheme:'upto', network:'eip155:8453', maxAmountRequired:'10000', ... }] }

2. SDK Internal -> paymentHandler({ url, method, body, accepts })   (local signing, 0 RTT)
   <- { headers: { 'PAYMENT-SIGNATURE': '<base64-envelope>' } }

3. SDK -> /openai/v1/chat/completions               (PAYMENT-SIGNATURE header injected)
   <- 200 + business response   (settlement completed on the server)

{
  "x402Version": 2,
  "accepted": {
    "scheme": "upto",
    "network": "eip155:8453"
  },
  "payload": {
    "permit2": {
      "permitted": [{ "token": "0x...USDC", "amount": "10000" }],
      "nonce": "...",
      "deadline": "..."
    },
    "witness": { "...metered-billing-fields..." },
    "signature": "0x..."
  }
}

npm install @acedatacloud/sdk @acedatacloud/x402-client

@acedatacloud/sdk@2026.504.2
@acedatacloud/x402-client@2026.531.3

export interface X402PaymentHandlerOptions {
  network: 'solana' | 'base' | 'skale';
  solanaWallet?: SolanaWalletAdapter;       // required when network='solana'
  evmProvider?: EVMProvider;                // required when network='base'/'skale', EIP-1193
  evmAddress?: string;                      // required when network='base'/'skale'
  preferScheme?: 'exact' | 'upto';
}

import { AceDataCloud } from '@acedatacloud/sdk';
import { createX402PaymentHandler } from '@acedatacloud/x402-client';

// 1. Prompt the user to connect their wallet
const accounts: string[] = await (window as any).ethereum.request({
  method: 'eth_requestAccounts'
});
const userAddress = accounts[0];

// 2. Switch to Base mainnet
await (window as any).ethereum.request({
  method: 'wallet_switchEthereumChain',
  params: [{ chainId: '0x2105' }]   // 8453 = Base
});

// 3. Construct SDK client, inject X402 handler
//    Note: Do not pass apiToken, let SDK follow the 402 path
const client = new AceDataCloud({
  paymentHandler: createX402PaymentHandler({
    network: 'base',
    evmProvider: (window as any).ethereum,
    evmAddress: userAddress,
    preferScheme: 'upto'   // required for chat types
  })
});

// 4. Call normally
const res: any = await client.openai.chat.completions.create({
  model: 'gpt-4o-mini',
  messages: [{ role: 'user', content: 'hi' }],
  max_tokens: 20
});
console.log(res.choices[0].message.content);

import { AceDataCloud } from '@acedatacloud/sdk';
import { createX402PaymentHandler } from '@acedatacloud/x402-client';
import { createWalletClient, http } from 'viem';
import { base } from 'viem/chains';
import { privateKeyToAccount } from 'viem/accounts';

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY as `0x${string}`);
const walletClient = createWalletClient({
  account,
  chain: base,
  transport: http(process.env.BASE_RPC_URL)
});

// The viem WalletClient comes with EIP-1193 compatible .request(), which can be used directly as evmProvider
const client = new AceDataCloud({
  paymentHandler: createX402PaymentHandler({
    network: 'base',
    evmProvider: walletClient as any,   // walletClient.request meets EIP-1193
    evmAddress: account.address,
    preferScheme: 'upto'
  })
});

const res: any = await client.openai.chat.completions.create({
  model: 'gpt-4o-mini',
  messages: [{ role: 'user', content: 'hi' }],
  max_tokens: 20
});
console.log(res.choices[0].message.content);

import { AceDataCloud } from '@acedatacloud/sdk';
import { createX402PaymentHandler } from '@acedatacloud/x402-client';
import { Keypair } from '@solana/web3.js';

const kp = Keypair.fromSecretKey(/* Uint8Array */);

const client = new AceDataCloud({
  paymentHandler: createX402PaymentHandler({
    network: 'solana',
    solanaWallet: {
      publicKey: kp.publicKey,
      signTransaction: async (tx) => {
        tx.sign([kp]);
        return tx;
      }
    }
  })
});

pip install acedatacloud acedatacloud-x402

acedatacloud==2026.4.26.1
acedatacloud-x402==2026.5.31.3

import os
from acedatacloud import AceDataCloud
from acedatacloud_x402 import (
    create_x402_payment_handler,
    EVMAccountSigner,
)

# 1. Construct signer from private key
signer = EVMAccountSigner.from_private_key(os.environ["EVM_PRIVATE_KEY"])

# 2. Construct SDK: do not pass api_token, let the SDK follow the 402 path
client = AceDataCloud(
    payment_handler=create_x402_payment_handler(
        network="base",
        evm_signer=signer,
        prefer_scheme="upto",   # chat types must choose upto
    )
)

# 3. Normal call
res = client.openai.chat.completions.create(
    model="gpt-4o-mini",
    messages=[{"role": "user", "content": "hi"}],
    max_tokens=20,
)
print(res["choices"][0]["message"]["content"])

import os
from acedatacloud import AceDataCloud
from acedatacloud_x402 import (
    create_x402_payment_handler,
    SolanaKeypairSigner,
)

signer = SolanaKeypairSigner.from_secret_key_base58(os.environ["SOLANA_PRIVATE_KEY"])

client = AceDataCloud(
    payment_handler=create_x402_payment_handler(
        network="solana",
        solana_signer=signer,
        rpc_url="https://api.mainnet-beta.solana.com",  # optional
    )
)

from acedatacloud_x402 import approve_permit2

tx_hash = approve_permit2(
    evm_signer=signer,
    rpc_url=os.environ["BASE_RPC_URL"],
)
print("permit2_approve_tx", tx_hash)

// /tmp/sdk-tests/ts/x402-wire-test.ts
import { AceDataCloud } from '@acedatacloud/sdk';
import { createX402PaymentHandler } from '@acedatacloud/x402-client';

const handler = createX402PaymentHandler({
  network: 'base',
  evmProvider: { request: async () => '0x0' } as any,   // placeholder provider
  evmAddress: '0x0000000000000000000000000000000000000000',
  preferScheme: 'upto'
});

console.log('handler_type', typeof handler);   // function

const client = new AceDataCloud({
  paymentHandler: handler
});

console.log('client_ctor_ok', client.constructor.name);   // AceDataCloud

handler_type function
client_ctor_ok AceDataCloud

Two modes can coexist—within the same process, different authentication methods can be configured for different `client` instances.

## VI. Common Pitfalls

1. **The chat class must use `preferScheme=upto`**: Using `exact` will cause the facilitator to deduct USDC based on `maxAmountRequired` (not the actual usage).
2. **Do not pass the raw private key to `createX402PaymentHandler` on the Node side**: The TS package does not accept `{ privateKey }`, it must be wrapped in an EIP-1193 provider (recommended viem `WalletClient`).
3. **The first call is a double signature**: The first time signs the Permit2 approve (on-chain, incurs gas), the second time signs the X402 envelope (off-chain). Subsequent calls only require the second signature.
4. **Solana does not have the concept of Permit2**: Directly sign SPL token transfer authorization, no need for approval; however, currently, only `exact` is supported on the Solana chain.
5. **Distinguishing between business errors and payment errors**: 402 → handler failure throws `X402SignError` (specific type varies by chain); subsequent resends will still classify business interface errors (401 / 422 / 5xx) as ordinary SDK exceptions.
6. **The most stable way to adapt `viem`**: `evmProvider: walletClient as any` will lose type checking but has the best compatibility; if you want to retain types, use viem's `.transport.request` to wrap a layer of `{ request }` object to pass in.

## Learn More

- 📦 [`@acedatacloud/x402-client` on npm](https://www.npmjs.com/package/@acedatacloud/x402-client)
- 🐍 [`acedatacloud-x402` on PyPI](https://pypi.org/project/acedatacloud-x402/)
- 🗂 [X402 client source code](https://github.com/AceDataCloud/SDK/tree/main/x402-client)
- 🔗 [X402 integration guide](https://platform.acedata.cloud/documents/x402-integration)
- 📘 [TypeScript SDK integration tutorial](https://platform.acedata.cloud/documents/sdk-typescript)
- 🐍 [Python SDK integration tutorial](https://platform.acedata.cloud/documents/sdk-python)
- 🌐 [x402.org](https://www.x402.org/)