Added example to show x402 header from Server

examples/02-show-x402-header.js

@@ -0,0 +1,61 @@
+/**
+ * x402 v2 — fetch a protected URL like curl -i, then decode PAYMENT-REQUIRED.
+ * Run from repo root:
+ *   `node examples/02-show-x402-header.js`
+ * Optional: `X402_SAMPLE_URL=https://host/path node examples/02-show-x402-header.js`
+ */
+import axios from 'axios'
+import { decodePaymentRequiredHeader } from '@x402/core/http'
+
+const url =
+  process.env.X402_SAMPLE_URL ||
+  'https://x402.fullstack.cash/v6/full-node/blockchain/getBlockchainInfo'
+
+function headerString (headers, name) {
+  const lower = name.toLowerCase()
+  const raw =
+    headers?.[lower] ??
+    headers?.[name] ??
+    (typeof headers?.get === 'function'
+      ? headers.get(lower) ?? headers.get(name)
+      : undefined)
+  return typeof raw === 'string' ? raw : Array.isArray(raw) ? raw[0] : undefined
+}
+
+async function main () {
+  const res = await axios.get(url, {
+    validateStatus: () => true
+  })
+
+  console.log(`HTTP ${res.status}`)
+  console.log(`content-type: ${headerString(res.headers, 'content-type') ?? '(none)'}`)
+  console.log(
+    `access-control-expose-headers: ${headerString(res.headers, 'access-control-expose-headers') ?? '(none)'}`
+  )
+
+  const paymentRequiredRaw = headerString(res.headers, 'payment-required')
+  if (!paymentRequiredRaw) {
+    console.error('\nNo PAYMENT-REQUIRED header on this response.')
+    process.exit(1)
+  }
+
+  console.log('\n--- PAYMENT-REQUIRED (decoded) ---\n')
+  try {
+    const decoded = decodePaymentRequiredHeader(paymentRequiredRaw)
+    console.log(JSON.stringify(decoded, null, 2))
+  } catch (err) {
+    console.error('\nFailed to decode PAYMENT-REQUIRED:', err?.message || err)
+    process.exit(1)
+  }
+
+  console.log('\n--- response body ---\n')
+  const body = res.data
+  console.log(
+    typeof body === 'string' ? body : JSON.stringify(body, null, 2)
+  )
+}
+
+main().catch((err) => {
+  console.error(err)
+  process.exit(1)
+})