x402 SDK Client Patterns

Reusable client code and common files for Bankr SDK projects.

bankr-client.ts

The core SDK client module for all Bankr SDK projects:

import "dotenv/config"; import { BankrClient } from "@bankr/sdk";

// ============================================ // Validation // ============================================

if (!process.env.BANKR_PRIVATE_KEY) { throw new Error( "BANKR_PRIVATE_KEY environment variable is required. " + "This wallet pays $0.01 USDC per request (needs USDC on Base)." ); }

// ============================================ // Client Setup // ============================================

/**

Bankr SDK Client
Provides AI-powered Web3 operations with x402 micropayments.
Each API request costs $0.01 USDC (paid from payment wallet on Base).
@example
import { bankrClient } from "./bankr-client";
// Token swap
const swap = await bankrClient.promptAndWait({
prompt: "Swap 0.1 ETH to USDC on Base",
});
// Check balances
const balances = await bankrClient.promptAndWait({
prompt: "What are my token balances?",
});
@see https://www.npmjs.com/package/@bankr/sdk */ export const bankrClient = new BankrClient({ // Required: Payment wallet private key // This wallet pays $0.01 USDC per API request (must have USDC on Base) privateKey: process.env.BANKR_PRIVATE_KEY as 0x${string},

// Optional: Override receiving wallet address // If not set, tokens are sent to the payment wallet address walletAddress: process.env.BANKR_WALLET_ADDRESS,

// Optional: API endpoint (defaults to production) ...(process.env.BANKR_API_URL && { baseUrl: process.env.BANKR_API_URL }), });

// Export the wallet address for reference export const walletAddress = bankrClient.getWalletAddress();

// ============================================ // Types (re-exported from SDK) // ============================================

export type { JobStatusResponse, Transaction } from "@bankr/sdk";

executor.ts

Transaction execution helper using viem:

import { createWalletClient, http, type WalletClient } from "viem"; import { privateKeyToAccount } from "viem/accounts"; import { base, mainnet, polygon } from "viem/chains"; import type { Transaction } from "@bankr/sdk";

// Chain configuration const chains = { 8453: base, 1: mainnet, 137: polygon, } as const;

// Create wallet client for transaction execution const account = privateKeyToAccount( process.env.BANKR_PRIVATE_KEY as 0x${string} );

function getWalletClient(chainId: number): WalletClient { const chain = chains[chainId as keyof typeof chains]; if (!chain) { throw new Error(Unsupported chain ID: ${chainId}); }

return createWalletClient({ account, chain, transport: http(), }); }

/**

Execute a transaction returned by the Bankr SDK
@example
const result = await bankrClient.promptAndWait({
prompt: "Swap 0.1 ETH to USDC",
});
if (result.transactions?.length) {
const hash = await executeTransaction(result.transactions[0]);
console.log("Transaction:", hash);
}

*/ export async function executeTransaction(tx: Transaction): Promise<string> { const txData = tx.metadata.transaction; const client = getWalletClient(txData.chainId);

console.log(Executing ${tx.type} on chain ${txData.chainId}...);

const hash = await client.sendTransaction({ to: txData.to as 0x${string}, data: txData.data as 0x${string}, value: BigInt(txData.value || "0"), gas: BigInt(txData.gas), });

console.log(Transaction submitted: ${hash}); return hash; }

/**

Execute all transactions from a Bankr result */ export async function executeAllTransactions( transactions: Transaction[] ): Promise<string[]> { const hashes: string[] = [];

for (const tx of transactions) { const hash = await executeTransaction(tx); hashes.push(hash); }

return hashes; }

Common Files

package.json

Base package.json for all Bankr SDK projects:

{ "name": "{project-name}", "version": "0.1.0", "description": "{description}", "type": "module", "main": "dist/index.js", "scripts": { "build": "tsc", "start": "node dist/index.js", "dev": "tsx src/index.ts" }, "dependencies": { "@bankr/sdk": "^1.0.0", "dotenv": "^16.3.1", "viem": "^2.0.0" }, "devDependencies": { "@types/node": "^20.10.0", "tsx": "^4.7.0", "typescript": "^5.3.0" } }

Framework-Specific Dependencies

Add based on project template:

Web Service (Express):

"dependencies": { "express": "^4.18.0" }, "devDependencies": { "@types/express": "^4.17.21" }

CLI:

"dependencies": { "commander": "^12.0.0" }

tsconfig.json

TypeScript configuration:

{ "compilerOptions": { "target": "ES2022", "module": "NodeNext", "moduleResolution": "NodeNext", "outDir": "./dist", "rootDir": "./src", "strict": true, "esModuleInterop": true, "skipLibCheck": true, "forceConsistentCasingInFileNames": true, "declaration": true }, "include": ["src/**/*"], "exclude": ["node_modules", "dist"] }

.env.example

Environment variables template:

Bankr SDK Configuration

See: https://docs.bankr.bot

Required: Payment wallet private key

This wallet pays $0.01 USDC per API request (must have USDC on Base)

Format: 64 hex characters with 0x prefix

BANKR_PRIVATE_KEY=0x

Optional: Receiving wallet address

Tokens from swaps/purchases go here. Defaults to payment wallet if not set.

BANKR_WALLET_ADDRESS=0x

Optional: API endpoint override (defaults to https://api.bankr.bot)

BANKR_API_URL=https://api.bankr.bot

.gitignore

Standard ignore patterns:

Dependencies

node_modules/

Build output

dist/

Environment

.env .env.local .env.*.local

Logs

.log npm-debug.log

IDE

.idea/ .vscode/ *.swp *.swo

OS

.DS_Store Thumbs.db

Testing

coverage/

Usage Patterns

Basic Usage

import { bankrClient } from "./bankr-client";

const result = await bankrClient.promptAndWait({ prompt: "What is the price of ETH?", onStatusUpdate: (msg) => console.log("Progress:", msg), });

console.log(result.response);

With Transaction Execution

import { bankrClient } from "./bankr-client"; import { executeTransaction } from "./executor";

const result = await bankrClient.promptAndWait({ prompt: "Swap 0.1 ETH to USDC on Base", });

if (result.status === "completed" && result.transactions?.length) { // Review before executing console.log("Transaction ready:", result.transactions[0].type); console.log("Details:", result.transactions[0].metadata.ORIGINAL_TX_DATA);

// Execute const hash = await executeTransaction(result.transactions[0]); console.log("Executed:", hash); }

With Error Handling

import { bankrClient } from "./bankr-client"; import { executeAllTransactions } from "./executor";

async function performSwap(prompt: string) { try { const result = await bankrClient.promptAndWait({ prompt, onStatusUpdate: console.log, });

if (result.status === "completed") {
  console.log("Success:", result.response);

  if (result.transactions?.length) {
    const hashes = await executeAllTransactions(result.transactions);
    console.log("Transactions:", hashes);
  }
} else if (result.status === "failed") {
  console.error("Failed:", result.error);
}

} catch (error) { console.error("Error:", error.message); } }

Query Without Transactions

import { bankrClient } from "./bankr-client";

// Balance queries don't return transactions const balances = await bankrClient.promptAndWait({ prompt: "What are my balances on Base?", });

console.log(balances.response);

// Price queries const price = await bankrClient.promptAndWait({ prompt: "Price of DEGEN", });

console.log(price.response);

SDK Reference

Consult the sdk-capabilities skill for:

Complete operation reference
Supported chains and tokens
Example prompts for each operation

Consult the sdk-token-swaps skill for:

Swap patterns and approval handling
Transaction execution details

bankr x402 sdk - client patterns

Safety Notice

Copy this and send it to your AI assistant to learn