feat: add comment support for Lightning payments in BTCPay and Strike services

- Enhanced the sendPaymentWithAddress method in BTCPayService and StrikeService to accept an optional comment parameter.
- Updated resolveLightningAddress to include the comment in the callback URL if supported by the LNURL-pay endpoint.
- Modified PaymentService to construct a descriptive comment for Lightning invoices, improving clarity for users.

These changes enhance the payment experience by allowing users to include contextual information with their transactions.

backend/src/payment/providers/services/btcpay.service.ts

@@ -345,12 +345,13 @@ export class BTCPayService implements LightningService {
   async sendPaymentWithAddress(
     address: string,
     payment: Payment,
+    comment?: string,
   ): Promise<LightningPaymentDTO> {
     try {
       const sats = Math.floor(payment.milisatsAmount / 1000);
 
       // Resolve the Lightning address to a BOLT11 invoice
-      const bolt11 = await this.resolveLightningAddress(address, sats);
+      const bolt11 = await this.resolveLightningAddress(address, sats, comment);
 
       // Pay the BOLT11 via BTCPay's internal Lightning node
       const payUrl = this.storeUrl('/lightning/BTC/invoices/pay');
@@ -578,6 +579,7 @@ export class BTCPayService implements LightningService {
   private async resolveLightningAddress(
     address: string,
     amountSats: number,
+    comment?: string,
   ): Promise<string> {
     const [username, domain] = address.split('@');
     if (!username || !domain) {
@@ -606,6 +608,16 @@ export class BTCPayService implements LightningService {
     const callbackUrl = new URL(lnurlData.callback);
     callbackUrl.searchParams.set('amount', amountMillisats.toString());
 
+    // Include a descriptive comment if the endpoint supports it.
+    // LNURL-pay endpoints advertise commentAllowed (max char length).
+    const commentAllowed = lnurlData.commentAllowed || 0;
+    if (comment && commentAllowed > 0) {
+      callbackUrl.searchParams.set(
+        'comment',
+        comment.slice(0, commentAllowed),
+      );
+    }
+
     const { data: invoiceData } = await axios.get(callbackUrl.toString(), { timeout: 10_000 });
 
     if (invoiceData.status === 'ERROR') {

backend/src/payment/providers/services/lightning.service.ts

@@ -5,6 +5,7 @@ export interface LightningService {
   sendPaymentWithAddress(
     address: string,
     payment: Payment,
+    comment?: string,
   ): Promise<LightningPaymentDTO>;
 
   validateAddress(address: string): Promise<boolean>;

backend/src/payment/providers/services/strike.service.ts

@@ -23,6 +23,7 @@ export class StrikeService implements LightningService {
   async sendPaymentWithAddress(
     address: string,
     payment: Payment,
+    comment?: string,
     currency: 'USD' | 'BTC' = 'BTC',
   ): Promise<LightningPaymentDTO> {
     try {
@@ -39,7 +40,7 @@ export class StrikeService implements LightningService {
               : payment.usdAmount,
           currency,
         },
-        description: isBlinkWallet ? undefined : 'Tip from IndeeHub',
+        description: isBlinkWallet ? undefined : (comment || 'Tip from IndeeHub'),
       });
 
       const createPaymentConfig = {

backend/src/payment/services/payment.service.ts

@@ -233,7 +233,7 @@ export class PaymentService {
       order: {
         [column]: 'DESC',
       },
-      relations: ['filmmaker', 'filmmaker.paymentMethods'],
+      relations: ['filmmaker', 'filmmaker.paymentMethods', 'content'],
       take: 5,
     };
 
@@ -347,10 +347,16 @@ export class PaymentService {
     }
 
     try {
+      // Build a descriptive comment for the Lightning invoice so the
+      // creator's wallet shows what the payment is for.
+      const contentTitle = shareholder.content?.title || 'content';
+      const payoutComment = `IndeeHub ${type} payout - ${contentTitle}`;
+
       this.logger.log(`[payout:${type}] Sending ${rounded} sats to ${selectedLightningAddress.lightningAddress}...`);
       const providerPayment = await this.provider.sendPaymentWithAddress(
         selectedLightningAddress.lightningAddress,
         payment,
+        payoutComment,
       );
 
       payment.providerId = providerPayment.id;