app working with sandbox

lib/utils/connect_bank.dart

@@ -0,0 +1,59 @@
+/// Shared UI helpers for bank connect actions.
+library;
+
+import 'package:flutter/material.dart';
+
+import '../providers/bank_provider.dart';
+import '../screens/bank_auth_screen.dart';
+
+Future<void> runConnectBank(BuildContext context, BankController bank) async {
+  final start = await bank.beginConnect();
+  if (!context.mounted) return;
+
+  if (start == null) {
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(content: Text(bank.error ?? 'Could not start bank connect')),
+    );
+    return;
+  }
+
+  final result = await Navigator.of(context).push<BankAuthResult>(
+    MaterialPageRoute(
+      builder: (_) => BankAuthScreen(
+        authUrl: start.authUrl,
+        pendingState: start.state,
+      ),
+    ),
+  );
+
+  if (!context.mounted) return;
+  if (result == null) return;
+
+  if (result.error != null && result.error!.isNotEmpty) {
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(content: Text('Bank auth failed: ${result.error}')),
+    );
+    return;
+  }
+
+  if (!result.hasCode) {
+    ScaffoldMessenger.of(context).showSnackBar(
+      const SnackBar(content: Text('Bank redirect missing code')),
+    );
+    return;
+  }
+
+  final linked = await bank.completeWithCode(
+    code: result.code!,
+    state: result.state,
+  );
+  if (!context.mounted) return;
+
+  ScaffoldMessenger.of(context).showSnackBar(
+    SnackBar(
+      content: Text(
+        linked ? 'Bank linked' : (bank.error ?? 'Could not complete connect'),
+      ),
+    ),
+  );
+}