fix: return sealed CollectBankAccountResult for bank account collection

Native SDKs return either a payment intent or a setup intent depending on
the client secret passed to collectBankAccount /
verifyPaymentIntentWithMicrodeposits, but the platform interface only
typed the result as PaymentIntent. The setup intent branch therefore
failed to parse against PaymentIntent.fromJson, which requires fields
(amount, currency, captureMethod, confirmationMethod) that are not
present on a setup intent payload.

Introduce a sealed CollectBankAccountResult union so both variants can
be parsed by their own freezed + json_serializable generated factories
without any hand-written field extraction or status mapping.

Author: BiAksoy

example/lib/screens/regional_payment_methods/us_bank_account_direct_debit_screen.dart

@@ -134,10 +134,15 @@ class _UsBankAccountDirectDebitScreenState
           ),
         );
 
-        if (result.status == PaymentIntentsStatus.RequiresConfirmation) {
+        final paymentIntent = switch (result) {
+          CollectBankAccountPaymentIntentResult(:final paymentIntent) =>
+            paymentIntent,
+          CollectBankAccountSetupIntentResult() => null,
+        };
+        if (paymentIntent?.status == PaymentIntentsStatus.RequiresConfirmation) {
           setState(() {
             canConfirm = true;
-            clientSecretForConfirm = result.clientSecret;
+            clientSecretForConfirm = paymentIntent!.clientSecret;
           });
           if (context.mounted) {
             scaffoldMessenger.showSnackBar(

packages/stripe/lib/src/stripe.dart

@@ -632,8 +632,10 @@ class Stripe {
 
   /// Collect the bankaccount details for the payment intent.
   ///
-  /// Only US bank accounts are supported.
-  Future<PaymentIntent> collectBankAccount({
+  /// Only US bank accounts are supported. The returned
+  /// [CollectBankAccountResult] is a sealed union containing either a
+  /// [PaymentIntent] or a [SetupIntent] depending on [isPaymentIntent].
+  Future<CollectBankAccountResult> collectBankAccount({
     /// Whether the clientsecret is associated with setup or paymentintent
     required bool isPaymentIntent,
 
@@ -655,8 +657,10 @@ class Stripe {
   /// Verify the bank account with microtransactions
   ///
   /// Only US bank accounts are supported.This method is only implemented for
-  /// iOS at the moment.
-  Future<PaymentIntent> verifyPaymentIntentWithMicrodeposits({
+  /// iOS at the moment. The returned [CollectBankAccountResult] is a sealed
+  /// union containing either a [PaymentIntent] or a [SetupIntent] depending on
+  /// [isPaymentIntent].
+  Future<CollectBankAccountResult> verifyPaymentIntentWithMicrodeposits({
     /// Whether the clientsecret is associated with setup or paymentintent
     required bool isPaymentIntent,
 

packages/stripe_platform_interface/lib/src/method_channel_stripe.dart

@@ -15,6 +15,7 @@ import 'package:stripe_platform_interface/src/result_parser.dart';
 
 import 'models/app_info.dart';
 import 'models/card_details.dart';
+import 'models/collect_bank_account_result.dart';
 import 'models/errors.dart';
 import 'models/payment_intents.dart';
 import 'models/payment_methods.dart';
@@ -569,7 +570,7 @@ class MethodChannelStripe extends StripePlatform {
   }
 
   @override
-  Future<PaymentIntent> collectBankAccount({
+  Future<CollectBankAccountResult> collectBankAccount({
     required bool isPaymentIntent,
     required String clientSecret,
     required CollectBankAccountParams params,
@@ -583,13 +584,14 @@ class MethodChannelStripe extends StripePlatform {
 
     _financialConnectionsEventHandler = params.onEvent;
 
-    return ResultParser<PaymentIntent>(
-      parseJson: (json) => PaymentIntent.fromJson(json),
-    ).parse(result: result!, successResultKey: 'paymentIntent');
+    return _parseCollectBankAccountResult(
+      result!,
+      isPaymentIntent: isPaymentIntent,
+    );
   }
 
   @override
-  Future<PaymentIntent> verifyPaymentIntentWithMicrodeposits({
+  Future<CollectBankAccountResult> verifyPaymentIntentWithMicrodeposits({
     required bool isPaymentIntent,
     required String clientSecret,
     required VerifyMicroDepositsParams params,
@@ -601,9 +603,26 @@ class MethodChannelStripe extends StripePlatform {
           'clientSecret': clientSecret,
         });
 
-    return ResultParser<PaymentIntent>(
-      parseJson: (json) => PaymentIntent.fromJson(json),
-    ).parse(result: result!, successResultKey: 'paymentIntent');
+    return _parseCollectBankAccountResult(
+      result!,
+      isPaymentIntent: isPaymentIntent,
+    );
+  }
+
+  CollectBankAccountResult _parseCollectBankAccountResult(
+    Map<String, dynamic> result, {
+    required bool isPaymentIntent,
+  }) {
+    if (isPaymentIntent) {
+      final paymentIntent = ResultParser<PaymentIntent>(
+        parseJson: (json) => PaymentIntent.fromJson(json),
+      ).parse(result: result, successResultKey: 'paymentIntent');
+      return CollectBankAccountResult.paymentIntent(paymentIntent);
+    }
+    final setupIntent = ResultParser<SetupIntent>(
+      parseJson: (json) => SetupIntent.fromJson(json),
+    ).parse(result: result, successResultKey: 'setupIntent');
+    return CollectBankAccountResult.setupIntent(setupIntent);
   }
 
   @override

packages/stripe_platform_interface/lib/src/models/collect_bank_account_result.dart

@@ -0,0 +1,21 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+import 'payment_intents.dart';
+import 'setup_intent.dart';
+
+part 'collect_bank_account_result.freezed.dart';
+
+/// Result of `collectBankAccount` / `verifyPaymentIntentWithMicrodeposits`.
+///
+/// Native SDKs return either a payment intent or a setup intent depending on
+/// the client secret that was supplied, so the result is modelled as a sealed
+/// union to keep both flows strongly typed.
+@freezed
+sealed class CollectBankAccountResult with _$CollectBankAccountResult {
+  const factory CollectBankAccountResult.paymentIntent(
+    PaymentIntent paymentIntent,
+  ) = CollectBankAccountPaymentIntentResult;
+
+  const factory CollectBankAccountResult.setupIntent(SetupIntent setupIntent) =
+      CollectBankAccountSetupIntentResult;
+}