feat: ( payment ) add changing payment for booking

apps/edr-payment-api/src/modules/intents/intents.service.ts

@@ -77,8 +77,27 @@ export class IntentsService {
       request.referenceId,
     );
     if (existing) {
-      const reusable = await this.reuseOrRetire(existing);
-      if (reusable) return this.toSnapshot(reusable);
+      // Payer switched method (e.g. Waafi → Telebirr) on an uncharged session: retire the
+      // open intent and fall through to open a fresh one for the new provider. Only safe
+      // while REQUIRES_ACTION — PROCESSING/SUCCEEDED intents may have money in flight, so
+      // they keep the reuse path (the switch is silently refused until they resolve).
+      const switchingProvider =
+        existing.provider !== request.provider &&
+        existing.status === ProviderPaymentStatus.REQUIRES_ACTION;
+      if (switchingProvider) {
+        await this.intentsRepository.update(existing.id, {
+          status: ProviderPaymentStatus.CANCELLED,
+          failureCode: "METHOD_CHANGED",
+          failureMessage: `Payer switched from ${existing.provider} to ${request.provider}`,
+        });
+        this.logger.log(
+          `intent ${existing.id} retired (METHOD_CHANGED ${existing.provider} → ${request.provider}) for ` +
+            `${request.service}/${request.referenceType}/${request.referenceId}`,
+        );
+      } else {
+        const reusable = await this.reuseOrRetire(existing);
+        if (reusable) return this.toSnapshot(reusable);
+      }
     }
 
     const provider = this.providers.get(request.provider);