x402 Payment Flow

1. App calls store()
       |
2. SDK sends request to broker
       |
3. Broker returns 402 Payment Required
       |
4. SDK invokes your payment callback
       |
5. Your callback executes payment
       |
6. Callback returns { txHash, network }
       |
7. SDK retries with payment proof
       |
8. Broker verifies and stores data
       |
9. SDK returns confirmed result

const result = await client.store(
  {
    collection: 'posts',
    data: [{
      title: 'My First Post',
      content: 'Stored on blockchain!',
      author: 'alice'
    }]
  },
  // Payment callback - SDK invokes this when server returns 402
  async (quote) => {
    console.log('Payment required:', quote.totalCostTia, 'TIA');
    console.log('Pay to:', quote.brokerAddress);

    // Execute blockchain payment
    const txHash = await wallet.sendTokens(
      quote.brokerAddress,
      quote.totalCostTia
    );

    // Return format is required - SDK uses this to retry the store
    return {
      txHash: txHash,
      network: 'mocha-4' // or 'celestia' for mainnet
    };
  },
  true // waitForConfirmation
);

console.log(`Confirmed at block ${result.block_height}`);

interface X402Quote {
  quoteId: string;           // Unique quote identifier
  totalCostTia: number;      // Total cost in TIA
  amountRaw: string;         // Amount in smallest units (utia)
  brokerAddress: string;     // Address to pay
  description: string;       // Payment description
  expiresAt: number;         // Unix timestamp for expiry
  chainType: 'cosmos' | 'evm' | 'solana';
  network: string;           // Network identifier
  asset: string;             // Asset identifier (e.g., "utia")
  tokenSymbol: string;       // Token symbol
  tokenDecimals: number;     // Decimal places
  paymentMethod: 'native' | 'x402-facilitator';
  facilitator?: string;      // Facilitator URL if applicable
  allOptions: X402PaymentRequirement[];
}

interface PaymentResult {
  txHash: string;    // Transaction hash from blockchain
  network: string;   // Network identifier ('mocha-4' or 'celestia')
}

const confirmed = await client.store(
  { collection: 'products', data: products },
  paymentCallback,
  true  // Waits for on-chain confirmation
);

console.log('Data confirmed at height:', confirmed.block_height);

const quick = await client.store(
  { collection: 'products', data: products },
  paymentCallback,
  false  // Returns immediately
);

console.log('Task ticket:', quick.ticket_id);

// Check status later
const status = await client.getTaskStatus(quick.ticket_id);
console.log('Status:', status.status);

import { SigningStargateClient } from '@cosmjs/stargate';

const paymentCallback = async (quote) => {
  // Connect to Keplr
  await window.keplr.enable('mocha-4');
  const signer = await window.keplr.getOfflineSignerOnlyAmino('mocha-4');
  const accounts = await signer.getAccounts();
  const userAddress = accounts[0].address;

  // Create signing client
  const client = await SigningStargateClient.connectWithSigner(
    'https://rpc-mocha.pops.one',
    signer
  );

  // Send payment
  const result = await client.sendTokens(
    userAddress,
    quote.brokerAddress,
    [{ denom: 'utia', amount: quote.amountRaw }],
    { amount: [{ denom: 'utia', amount: '20000' }], gas: '200000' }
  );

  return {
    txHash: result.transactionHash,
    network: 'mocha-4'
  };
};

// Use the callback
await client.store(
  { collection: 'data', data: [{ content: 'example' }] },
  paymentCallback,
  true
);

import { DirectSecp256k1HdWallet } from '@cosmjs/proto-signing';
import { SigningStargateClient } from '@cosmjs/stargate';

const paymentCallback = async (quote) => {
  const wallet = await DirectSecp256k1HdWallet.fromMnemonic(
    process.env.MNEMONIC,
    { prefix: 'celestia' }
  );
  const [account] = await wallet.getAccounts();

  const client = await SigningStargateClient.connectWithSigner(
    'https://rpc-mocha.pops.one',
    wallet
  );

  const result = await client.sendTokens(
    account.address,
    quote.brokerAddress,
    [{ denom: 'utia', amount: quote.amountRaw }],
    { amount: [{ denom: 'utia', amount: '20000' }], gas: '200000' }
  );

  return {
    txHash: result.transactionHash,
    network: 'mocha-4'
  };
};

import { PaymentVerificationError, OnchainDBError } from '@onchaindb/sdk';

try {
  await client.store(
    { collection: 'data', data: [{ content: 'example' }] },
    paymentCallback,
    true
  );
} catch (error) {
  if (error instanceof PaymentVerificationError) {
    console.log('Payment verification failed');
    console.log('Transaction hash:', error.txHash);
    console.log('Error:', error.message);
  } else if (error instanceof OnchainDBError) {
    console.log('OnchainDB error:', error.code, error.statusCode);
  }
}