fix(samples/kotlin): select crypto network when funding a quote from USDC

samples/frontend/src/steps/CreateQuote.tsx

@@ -13,20 +13,31 @@ interface Props {
 
 const SOURCE_CURRENCIES = ['USD', 'USDC'] as const
 
+// Currencies that fund over a crypto network and therefore require `cryptoNetwork`.
+const CRYPTO_SOURCE_CURRENCIES = ['USDC']
+// Networks a stablecoin funding source can deposit on.
+const CRYPTO_NETWORKS = ['BASE', 'ETHEREUM', 'POLYGON', 'SOLANA']
+
 export default function CreateQuote({ customerId, externalAccountId, destCurrency, onComplete, disabled }: Props) {
   const [body, setBody] = useState('')
   const [response, setResponse] = useState<string | null>(null)
   const [error, setError] = useState<string | null>(null)
   const [loading, setLoading] = useState(false)
   const [sourceCurrency, setSourceCurrency] = useState<string>(SOURCE_CURRENCIES[0])
+  const [cryptoNetwork, setCryptoNetwork] = useState<string>(CRYPTO_NETWORKS[0])
+
+  const isCryptoSource = CRYPTO_SOURCE_CURRENCIES.includes(sourceCurrency)
 
   useEffect(() => {
+    const source: Record<string, unknown> = {
+      sourceType: "REALTIME_FUNDING",
+      currency: sourceCurrency,
+      customerId: customerId ?? "<customer-id>"
+    }
+    // cryptoNetwork is required when funding from a crypto currency (e.g. USDC).
+    if (isCryptoSource) source.cryptoNetwork = cryptoNetwork
     setBody(JSON.stringify({
-      source: {
-        sourceType: "REALTIME_FUNDING",
-        currency: sourceCurrency,
-        customerId: customerId ?? "<customer-id>"
-      },
+      source,
       destination: {
         destinationType: "ACCOUNT",
         accountId: externalAccountId ?? "<external-account-id>"
@@ -35,7 +46,7 @@ export default function CreateQuote({ customerId, externalAccountId, destCurrenc
       lockedCurrencySide: "SENDING",
       purposeOfPayment: "GIFT"
     }, null, 2))
-  }, [customerId, externalAccountId, sourceCurrency, destCurrency])
+  }, [customerId, externalAccountId, sourceCurrency, destCurrency, isCryptoSource, cryptoNetwork])
 
   const submit = async () => {
     setLoading(true)
@@ -72,6 +83,23 @@ export default function CreateQuote({ customerId, externalAccountId, destCurrenc
           ))}
         </select>
       </div>
+      {isCryptoSource && (
+        <div className="mb-3">
+          <label htmlFor="crypto-network" className="block text-sm font-medium text-gray-300 mb-1">Funding Network</label>
+          <select
+            id="crypto-network"
+            value={cryptoNetwork}
+            onChange={(e) => setCryptoNetwork(e.target.value)}
+            disabled={disabled || loading}
+            className="w-full px-3 py-2 bg-gray-800 border border-gray-700 rounded text-sm text-gray-100 focus:outline-none focus:border-blue-500"
+          >
+            {CRYPTO_NETWORKS.map((n) => (
+              <option key={n} value={n}>{n}</option>
+            ))}
+          </select>
+          <p className="text-xs text-gray-500 mt-1">Required when funding from a crypto currency — the network the customer deposits {sourceCurrency} on.</p>
+        </div>
+      )}
       <JsonEditor value={body} onChange={setBody} disabled={disabled || loading} />
       <button
         onClick={submit}

samples/kotlin/src/main/kotlin/com/grid/sample/routes/Quotes.kt

@@ -120,6 +120,9 @@ private fun buildQuoteSource(sourceNode: JsonNode): QuoteSourceOneOf {
             .currency(sourceNode.get("currency").asText())
             .apply {
                 sourceNode.optText("customerId")?.let { customerId(it) }
+                // Required when funding from a crypto currency (e.g. USDC): selects the
+                // network the customer deposits on so the right deposit address is issued.
+                sourceNode.optText("cryptoNetwork")?.let { cryptoNetwork(it) }
             }
             .build()
         return QuoteSourceOneOf.ofRealtimeFundingQuoteSource(realtimeSource)