@puga-labs/x402-mantle-sdk for gasless API monetization with USDC payments on Mantle blockchain.

KEY INFO:
- Payments use USDC on Mantle (chainId: 5000, USDC: 0x09Bc4E0D864854c6aFB6eB9A9cdF58aC190D0dF9)
- USDC only - requires EIP-3009 (transferWithAuthorization) which only USDC supports on Mantle
- Users sign authorizations (gasless for them), facilitator executes transfers and pays gas
- Server returns 402 + payment requirements, client SDK handles flow automatically
- Price in USD: priceUsd: 0.01 = 1 cent, converted to USDC atomic units internally

IMPORTS:
- Server Express: import { mantlePaywall } from '@puga-labs/x402-mantle-sdk/server/express'
- Server Next.js: import { mantlePaywall } from '@puga-labs/x402-mantle-sdk/server/nextjs'
- Server Web (Hono/CF/Deno): import { mantlePaywall } from '@puga-labs/x402-mantle-sdk/server/web'
- Client React: import { useMantleX402, useEthersWallet } from '@puga-labs/x402-mantle-sdk/react'
- Client Vanilla: import { createMantleClient } from '@puga-labs/x402-mantle-sdk/client'

SERVER PATTERN (Self-Hosted - Recommended):
const pay = mantlePaywall({
  priceUsd: 0.01,
  payTo: '0xYourWalletAddress',
  facilitatorUrl: 'https://your-facilitator.com',
  facilitatorSecret: process.env.FACILITATOR_SECRET!  // Required for self-hosted
});
// Express: app.post('/api/endpoint', pay, handler)
// Next.js: export const POST = pay(async (req) => NextResponse.json({ result }))
// Web: app.post('/path', pay(async (req) => new Response(...)))

SERVER PATTERN (Hosted):
const pay = mantlePaywall({
  priceUsd: 0.01,
  payTo: '0xYourWalletAddress',
  projectKey: 'pk_xxx'  // Get from dashboard - no facilitatorUrl needed!
});

CLIENT PATTERN (React):
// facilitatorUrl auto-detected from backend 402 response - no config needed!
const { postWithPayment } = useMantleX402();
const { response, txHash } = await postWithPayment('/api/endpoint', { data });

CLIENT PATTERN (Vanilla):
// facilitatorUrl auto-detected from backend 402 response
const client = createMantleClient({
  resourceUrl: 'https://your-api.com',
  getProvider: () => window.ethereum,
  getAccount: () => userAddress
});
const { response, txHash } = await client.postWithPayment('/api/endpoint', { data });

CONFIG OPTIONS:
- facilitatorUrl: string - for self-hosted (your facilitator URL)
- facilitatorSecret: string - for self-hosted (required with facilitatorUrl)
- projectKey: string - for hosted facilitator (get from dashboard)
- onPaymentSettled: (entry) => void - callback with { from, to, valueAtomic, txHash, route }
- telemetry: { debug: true } - for analytics (auto-uses projectKey)

URLS:
- Dashboard & Project Keys: https://x402mantlesdk.xyz/dashboard
- Docs: https://x402mantlesdk.xyz/docs