feat: prefill rescan height with the saved Monero and Zcash restore height (#3669)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

cw_zcash/lib/src/zcash_wallet.dart

@@ -999,6 +999,14 @@ abstract class ZcashWalletBase
 
   static int zashiAnnouncedBlockHeight = 2419420;
 
+  Future<int?> getBirthHeight() async => runWithCoin(
+        accountId: accountId,
+        func: (final coin) async => (await zkool_account.listAccounts(c: coin))
+            .where((final a) => a.id == accountId)
+            .firstOrNull
+            ?.birth,
+      );
+
   Future<dynamic> _getAddressesForAccount(final int id) async {
     return runWithCoin(
       accountId: id,

lib/src/screens/rescan/rescan_page.dart

@@ -25,6 +25,16 @@ class RescanPage extends StatefulWidget {
 class _RescanPageState extends State<RescanPage> {
   final TextEditingController _heightController = TextEditingController();
 
+  @override
+  void initState() {
+    super.initState();
+    widget._rescanViewModel.savedRestoreHeight.then((height) {
+      if (mounted && (height ?? 0) > 0 && _heightController.text.isEmpty) {
+        _heightController.text = '$height';
+      }
+    });
+  }
+
   @override
   Widget build(BuildContext context) {
     Widget child;

lib/view_model/rescan_view_model.dart

@@ -1,4 +1,6 @@
 import 'package:cake_wallet/bitcoin/bitcoin.dart';
+import 'package:cake_wallet/monero/monero.dart';
+import 'package:cake_wallet/zcash/zcash.dart';
 import 'package:cw_core/wallet_base.dart';
 import 'package:cw_core/wallet_type.dart';
 import 'package:mobx/mobx.dart';
@@ -32,6 +34,14 @@ abstract class RescanViewModelBase with Store {
   @computed
   bool get isMwebScan => wallet.type == WalletType.litecoin;
 
+  Future<int?> get savedRestoreHeight async => switch (wallet.type) {
+        WalletType.monero => wallet.walletInfo.restoreHeight != 0
+            ? wallet.walletInfo.restoreHeight
+            : monero!.getRestoreHeight(wallet),
+        WalletType.zcash => await zcash!.getBirthHeight(wallet),
+        _ => null,
+      };
+
   Future<bool> get isBitcoinMempoolAPIEnabled async =>
       wallet.type == WalletType.bitcoin && await bitcoin!.checkIfMempoolAPIIsEnabled(wallet);
 

lib/zcash/cw_zcash.dart

@@ -119,6 +119,9 @@ class CWZcash extends Zcash {
     return getAddress(wallet);
   }
 
+  @override
+  Future<int?> getBirthHeight(Object wallet) => (wallet as ZcashWallet).getBirthHeight();
+
   @override
   Map<String, String> getKeys(Object wallet) {
     final zcashWallet = wallet as ZcashWallet;

tool/configure.dart

@@ -1778,6 +1778,7 @@ abstract class Zcash {
   String getPrivateKey(WalletBase wallet);
   String getPublicKey(WalletBase wallet);
   Map<String, String> getKeys(Object wallet);
+  Future<int?> getBirthHeight(Object wallet);
 
   Object createZcashTransactionCredentials(
     List<Output> outputs, {