fix: show actual mint recipient in relay modal instead of connected wallet

When relaying on behalf of another user, the progress modal incorrectly displayed the connected wallet as the Receiver. Now parses the mintRecipient from the CCTP message bytes so the modal reflects who actually receives the USDC.

Made-with: Cursor

Author: jasbanza

public/app.js

@@ -772,6 +772,24 @@ function extractDestCaller(messageHex) {
     }
 }
 
+// Extract the mintRecipient from the CCTP message body.
+// Body starts at header offset 116; mintRecipient is at body+4+32 = offset 152, 32 bytes.
+// For EVM the 20-byte address sits in the last 20 bytes; for Solana it is a full 32-byte pubkey.
+function extractMintRecipientFromMessage(messageHex, isEvm) {
+    try {
+        const bytes = hexToBytes(messageHex);
+        if (bytes.length < 184) return null;
+        const recipientBytes = bytes.slice(152, 184);
+        if (isEvm) {
+            const addrBytes = recipientBytes.slice(12, 32);
+            return '0x' + Array.from(addrBytes).map(b => b.toString(16).padStart(2, '0')).join('');
+        }
+        return new PublicKey(recipientBytes).toBase58();
+    } catch (e) {
+        return null;
+    }
+}
+
 function getApiBase() {
     if (!elements.apiBase) return '';
     const raw = elements.apiBase.value.trim();
@@ -2053,8 +2071,9 @@ async function relayToSolana() {
     // Show modal if not already showing (for manual relay)
     const modalVisible = elements.progressModal && elements.progressModal.style.display === 'flex';
     if (!modalVisible) {
-        // For manual relay, show a simplified modal starting at step 3
-        const destAddress = elements.solanaDestAddress?.value?.trim() || walletPublicKey.toBase58();
+        const destAddress = extractMintRecipientFromMessage(messageHex, false)
+            || elements.solanaDestAddress?.value?.trim()
+            || walletPublicKey.toBase58();
         showProgressModal(destAddress, 0);
         updateModalStep(1, 'completed', 'Completed', 'Noble burn transaction (external)');
         updateModalStep(2, 'completed', 'Completed', 'Circle attestation verified');
@@ -2376,7 +2395,8 @@ async function relayToEvm() {
 
     const modalVisible = elements.progressModal && elements.progressModal.style.display === 'flex';
     if (!modalVisible) {
-        showProgressModal(evmAddress, 0);
+        const receiver = extractMintRecipientFromMessage(messageHex, true) || evmAddress;
+        showProgressModal(receiver, 0);
         updateModalStep(1, 'completed', 'Completed', 'Noble burn transaction (external)');
         updateModalStep(2, 'completed', 'Completed', 'Circle attestation verified');
     }