Merge pull request 'fix(wallet): send amount_msat when paying an amountless invoice' (#162) from fix/wallet-amountless-invoice into dev

Reviewed-on: #162

src/modules/wallet/services/WalletService.ts

@@ -2,6 +2,7 @@ import { ref, computed } from 'vue'
 import { BaseService } from '@/core/base/BaseService'
 import { injectService, SERVICE_TOKENS } from '@/core/di-container'
 import { config } from '@/lib/config'
+import { decode as decodeBolt11 } from 'light-bolt11-decoder'
 
 export interface PayLink {
   id: string
@@ -255,6 +256,19 @@ export default class WalletService extends BaseService {
           out: true,
           bolt11: lower
         }
+
+        // An amountless invoice carries no amount of its own, so the payer
+        // chooses one. LNbits rejects the payment outright ("Amount required
+        // for amountless invoices") unless `amount_msat` is supplied, so the
+        // caller's amount has to be forwarded explicitly. For an invoice that
+        // does carry an amount we deliberately send nothing: the invoice's own
+        // amount is authoritative and must not be overridden by the caller.
+        if (this.getInvoiceAmountMsat(lower) === 0) {
+          if (!request.amount || request.amount <= 0) {
+            throw new Error('This invoice has no amount. Enter an amount to send.')
+          }
+          body.amount_msat = Math.round(request.amount * 1000)
+        }
       } else if (dest.includes('@') || lower.startsWith('lnurl')) {
         // Lightning address or LNURL
         endpoint = `${config.api.baseUrl}/api/v1/payments/lnurl`
@@ -300,6 +314,26 @@ export default class WalletService extends BaseService {
     }
   }
   
+  /**
+   * Amount of a BOLT11 invoice in millisats, or `null` if it cannot be decoded.
+   *
+   * Returns `0` for an amountless invoice, which is a meaningful value here
+   * and not an error — hence `null` rather than `0` for the failure case.
+   */
+  private getInvoiceAmountMsat(bolt11: string): number | null {
+    try {
+      const decoded = decodeBolt11(bolt11)
+      const section = decoded.sections.find((s: any) => s.name === 'amount')
+      if (!section || section.value === undefined || section.value === null) return 0
+      return Number(section.value)
+    } catch (error) {
+      // Let the server be the authority on whether the invoice is payable;
+      // a local decode failure should not block the attempt.
+      console.warn('WalletService: could not decode invoice amount', error)
+      return null
+    }
+  }
+
   /**
    * Load existing pay links
    */