feat(app): settings menu with language and display unit

Add global AppConfig (config.json, blueprint §8) persisting language
and amount unit. CoinAmount gains unit-aware formatting and parsing
(PLM, mPLM, µPLM, sat), applied everywhere amounts are shown or
entered, including the send form. New Loc i18n layer (it/en) with
live-updating XAML bindings covering menu, wizard, wallet panel and
status messages.

The Impostazioni menu opens a dropdown with separate Lingua and Unità
entries (radio-checked submenus, applied and saved on click), ready to
host future settings.

src/App/Localization/Loc.cs

@@ -0,0 +1,166 @@
+using System.Collections.Generic;
+using System.ComponentModel;
+
+namespace PalladiumWallet.App.Localization;
+
+/// <summary>
+/// Localizzazione UI (blueprint §14): dizionario chiave → [it, en], con
+/// indicizzatore bindabile da XAML ({Binding Loc[chiave]}). Al cambio lingua
+/// notifica "Item[]" e tutte le binding si aggiornano.
+/// </summary>
+public sealed class Loc : INotifyPropertyChanged
+{
+    public static Loc Instance { get; } = new();
+
+    public static readonly string[] Languages = ["it", "en"];
+    public static readonly string[] LanguageNames = ["Italiano", "English"];
+
+    public string Language { get; private set; } = "it";
+
+    public event PropertyChangedEventHandler? PropertyChanged;
+
+    public void SetLanguage(string language)
+    {
+        if (Language == language || System.Array.IndexOf(Languages, language) < 0)
+            return;
+        Language = language;
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Item[]"));
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Language)));
+    }
+
+    public string this[string key] =>
+        Strings.TryGetValue(key, out var values)
+            ? values[Language == "en" ? 1 : 0]
+            : key;
+
+    public static string Tr(string key) => Instance[key];
+
+    private static readonly Dictionary<string, string[]> Strings = new()
+    {
+        // Menu
+        ["menu.file"] = ["_File", "_File"],
+        ["menu.file.new"] = ["Nuovo / ripristina wallet…", "New / restore wallet…"],
+        ["menu.file.open"] = ["Apri wallet da file…", "Open wallet from file…"],
+        ["menu.file.close"] = ["Chiudi wallet", "Close wallet"],
+        ["menu.net"] = ["_Rete", "_Network"],
+        ["menu.net.discover"] = ["Cerca altri server (peer)", "Discover servers (peers)"],
+        ["menu.net.resetcerts"] = ["Reset certificati SSL", "Reset SSL certificates"],
+        ["menu.settings"] = ["_Impostazioni", "_Settings"],
+        ["settings.unit.short"] = ["Unità", "Unit"],
+
+        // Wizard
+        ["wiz.net"] = ["Rete:", "Network:"],
+        ["wiz.open.btn"] = ["Apri il wallet esistente", "Open existing wallet"],
+        ["wiz.new.btn"] = ["Crea un nuovo wallet", "Create a new wallet"],
+        ["wiz.restore.btn"] = ["Ripristina da seed", "Restore from seed"],
+        ["wiz.open.title"] = ["Apri il wallet", "Open the wallet"],
+        ["wiz.open.placeholder"] = ["Password del file (vuoto se non impostata)", "File password (empty if not set)"],
+        ["wiz.open.ok"] = ["Apri", "Open"],
+        ["wiz.seed.title"] = ["Il tuo seed (12 parole)", "Your seed (12 words)"],
+        ["wiz.seed.warning"] = [
+            "Scrivi le parole su carta, nell'ordine. Chi le possiede controlla i fondi; se le perdi, i fondi sono irrecuperabili.",
+            "Write the words on paper, in order. Whoever holds them controls the funds; if you lose them, funds are unrecoverable."],
+        ["wiz.seed.next"] = ["Le ho scritte — Avanti", "I wrote them down — Next"],
+        ["wiz.confirm.title"] = ["Conferma il seed", "Confirm the seed"],
+        ["wiz.confirm.placeholder"] = ["Reinserisci le 12 parole separate da spazi", "Re-enter the 12 words separated by spaces"],
+        ["wiz.words.title"] = ["Ripristina da seed", "Restore from seed"],
+        ["wiz.words.placeholder"] = ["Mnemonica BIP39 (12 o 24 parole separate da spazi)", "BIP39 mnemonic (12 or 24 words separated by spaces)"],
+        ["wiz.passphrase.title"] = ["Passphrase opzionale", "Optional passphrase"],
+        ["wiz.passphrase.placeholder"] = ["Lascia vuoto per non usarla", "Leave empty to skip"],
+        ["wiz.password.title"] = ["Password del file wallet", "Wallet file password"],
+        ["wiz.password.placeholder"] = ["Consigliata (vuoto = file in chiaro su disco)", "Recommended (empty = plaintext file on disk)"],
+        ["wiz.password.create"] = ["Crea il wallet", "Create wallet"],
+        ["wiz.back"] = ["Indietro", "Back"],
+        ["wiz.next"] = ["Avanti", "Next"],
+
+        // Pannello wallet
+        ["wallet.close"] = ["Chiudi wallet", "Close wallet"],
+        ["wallet.server"] = ["Server:", "Server:"],
+        ["wallet.connect"] = ["Connetti e sincronizza", "Connect and sync"],
+        ["wallet.manual"] = ["oppure host:porta manuale", "or manual host:port"],
+        ["wallet.discover"] = ["Cerca altri server", "Discover servers"],
+        ["wallet.resetcert"] = ["Reset cert.", "Reset certs"],
+        ["tab.receive"] = ["Ricevi", "Receive"],
+        ["tab.history"] = ["Storico", "History"],
+        ["tab.addresses"] = ["Indirizzi", "Addresses"],
+        ["tab.send"] = ["Invia", "Send"],
+        ["receive.next"] = ["Prossimo indirizzo non usato:", "Next unused address:"],
+        ["receive.hint"] = [
+            "Ogni pagamento ricevuto qui comparirà nello storico alla prossima sincronizzazione.",
+            "Payments received here will appear in the history at the next synchronization."],
+        ["addr.type"] = ["Tipo", "Type"],
+        ["addr.index"] = ["Indice", "Index"],
+        ["addr.address"] = ["Indirizzo", "Address"],
+        ["addr.balance"] = ["Saldo", "Balance"],
+        ["addr.receive"] = ["ricezione", "receive"],
+        ["addr.change"] = ["change", "change"],
+        ["send.to"] = ["Indirizzo destinatario", "Recipient address"],
+        ["send.amount"] = ["Importo", "Amount"],
+        ["send.all"] = ["Invia tutto", "Send all"],
+        ["send.feerate"] = ["fee sat/vB:", "fee sat/vB:"],
+        ["send.prepare"] = ["Prepara transazione", "Prepare transaction"],
+        ["send.confirm"] = ["CONFERMA E TRASMETTI", "CONFIRM AND BROADCAST"],
+
+        // Stato connessione
+        ["conn.none"] = ["non connesso", "not connected"],
+        ["conn.disconnected"] = ["disconnesso", "disconnected"],
+        ["conn.reconnecting"] = ["riconnessione…", "reconnecting…"],
+        ["conn.error"] = ["errore di connessione", "connection error"],
+        ["conn.certchanged"] = ["certificato cambiato", "certificate changed"],
+        ["conn.connectedto"] = ["connesso a", "connected to"],
+        ["conn.connectingto"] = ["connessione a", "connecting to"],
+
+        // Messaggi di stato principali
+        ["msg.welcome.existing"] = [
+            "Trovato un wallet esistente su questa rete: aprilo, oppure creane un altro.",
+            "Found an existing wallet on this network: open it, or create another one."],
+        ["msg.welcome.new"] = [
+            "Benvenuto: crea un nuovo wallet o ripristina da seed.",
+            "Welcome: create a new wallet or restore from seed."],
+        ["msg.open.password"] = [
+            "Inserisci la password del file (lascia vuoto se non impostata).",
+            "Enter the file password (leave empty if not set)."],
+        ["msg.seed.write"] = [
+            "Scrivi le 12 parole SU CARTA, nell'ordine. Sono l'unico backup del wallet.",
+            "Write the 12 words ON PAPER, in order. They are the only backup of the wallet."],
+        ["msg.seed.retype"] = [
+            "Reinserisci le 12 parole per confermare di averle scritte.",
+            "Re-enter the 12 words to confirm you wrote them down."],
+        ["msg.seed.mismatch"] = [
+            "Le parole non corrispondono: ricontrolla quello che hai scritto su carta.",
+            "The words do not match: check what you wrote on paper."],
+        ["msg.words.enter"] = [
+            "Inserisci la mnemonica BIP39 (12 o 24 parole separate da spazi).",
+            "Enter the BIP39 mnemonic (12 or 24 words separated by spaces)."],
+        ["msg.words.invalid"] = [
+            "Mnemonica non valida (parole o checksum errati): ricontrolla.",
+            "Invalid mnemonic (wrong words or checksum): check again."],
+        ["msg.passphrase.info"] = [
+            "Passphrase BIP39 opzionale: cambia completamente il wallet. Se la usi, annotala A PARTE dal seed; se la perdi i fondi sono irrecuperabili. Lascia vuoto per non usarla.",
+            "Optional BIP39 passphrase: it derives a completely different wallet. If you use it, note it SEPARATELY from the seed; if lost, funds are unrecoverable. Leave empty to skip."],
+        ["msg.password.info"] = [
+            "Password di cifratura del file wallet su disco (consigliata). Non sostituisce il seed: serve solo a proteggere il file.",
+            "Encryption password for the wallet file on disk (recommended). It does not replace the seed: it only protects the file."],
+        ["msg.wrongpassword"] = ["Password errata.", "Wrong password."],
+        ["msg.opened"] = ["Wallet aperto: connessione al server…", "Wallet opened: connecting to server…"],
+        ["msg.synced"] = ["Sincronizzato", "Synchronized"],
+        ["msg.synced.detail"] = [
+            "transazioni verificate SPV. Aggiornamento in tempo reale attivo.",
+            "SPV-verified transactions. Real-time updates active."],
+        ["msg.height"] = ["altezza", "height"],
+        ["msg.pending"] = ["in attesa di conferma", "pending confirmation"],
+        ["msg.notspendable"] = ["non ancora spendibile", "not yet spendable"],
+        ["msg.settings.saved"] = ["Impostazioni salvate.", "Settings saved."],
+        ["msg.certreset"] = [
+            "Certificati SSL azzerati: riprova la connessione.",
+            "SSL certificates cleared: retry the connection."],
+        ["msg.error"] = ["Errore", "Error"],
+
+        // Finestra impostazioni
+        ["settings.title"] = ["Impostazioni", "Settings"],
+        ["settings.language"] = ["Lingua", "Language"],
+        ["settings.unit"] = ["Unità degli importi", "Amount unit"],
+        ["settings.ok"] = ["Salva", "Save"],
+        ["settings.cancel"] = ["Annulla", "Cancel"],
+    };
+}

src/App/ViewModels/MainWindowViewModel.cs

@@ -8,6 +8,7 @@ using Avalonia.Threading;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using NBitcoin;
+using PalladiumWallet.App.Localization;
 using PalladiumWallet.Core.Chain;
 using PalladiumWallet.Core.Crypto;
 using PalladiumWallet.Core.Net;
@@ -35,9 +36,67 @@ public partial class MainWindowViewModel : ViewModelBase
     private string? _walletPath;
     private string? _password;
     private ElectrumClient? _client;
+    private WalletSynchronizer? _synchronizer;
     private IReadOnlyDictionary<string, Transaction>? _lastTransactions;
     private BuiltTransaction? _pendingSend;
 
+    /// <summary>Notifica arrivata durante una sync: si risincronizza appena finita.</summary>
+    private bool _resyncRequested;
+
+    /// <summary>Configurazione globale (§8): lingua e unità.</summary>
+    private AppConfig _config = AppConfig.Load();
+
+    /// <summary>Stringhe localizzate, bindabili da XAML come Loc[chiave].</summary>
+    public Loc Loc => Loc.Instance;
+
+    /// <summary>Unità corrente per il campo importo del pannello Invia.</summary>
+    public string UnitLabel => _config.Unit;
+
+    public AppConfig CurrentConfig => _config;
+
+    // Spunte del menu Impostazioni (ToggleType Radio).
+    public bool IsLangIt => _config.Language == "it";
+    public bool IsLangEn => _config.Language == "en";
+    public bool IsUnitPlm => _config.Unit == "PLM";
+    public bool IsUnitMilli => _config.Unit == "mPLM";
+    public bool IsUnitMicro => _config.Unit == "µPLM";
+    public bool IsUnitSat => _config.Unit == "sat";
+
+    [RelayCommand]
+    private void SetLanguage(string language)
+    {
+        _config.Language = language;
+        ApplySettings(_config);
+    }
+
+    [RelayCommand]
+    private void SetUnit(string unit)
+    {
+        _config.Unit = unit;
+        ApplySettings(_config);
+    }
+
+    /// <summary>Applica e persiste le impostazioni (§8).</summary>
+    public void ApplySettings(AppConfig config)
+    {
+        _config = config;
+        _config.Save();
+        Loc.SetLanguage(config.Language);
+        OnPropertyChanged(nameof(UnitLabel));
+        OnPropertyChanged(nameof(IsLangIt));
+        OnPropertyChanged(nameof(IsLangEn));
+        OnPropertyChanged(nameof(IsUnitPlm));
+        OnPropertyChanged(nameof(IsUnitMilli));
+        OnPropertyChanged(nameof(IsUnitMicro));
+        OnPropertyChanged(nameof(IsUnitSat));
+        ApplyCache(_doc?.Cache);
+        StatusMessage = Loc.Tr("msg.settings.saved");
+    }
+
+    /// <summary>Formatta un importo nell'unità scelta nelle impostazioni.</summary>
+    private string Fmt(long sats, bool withLabel = true) =>
+        CoinAmount.FormatIn(sats, _config.Unit, withLabel);
+
     /// <summary>File in attesa di password (apertura da menu File → Apri).</summary>
     private string? _pendingOpenPath;
 
@@ -65,11 +124,43 @@ public partial class MainWindowViewModel : ViewModelBase
     [ObservableProperty]
     private string statusMessage = "";
 
-    // ---- pannello setup ----
+    // ---- wizard di setup (§15): un passo alla volta ----
+
+    public const string StepStart = "start";
+    public const string StepOpen = "open";
+    public const string StepShowSeed = "show-seed";
+    public const string StepConfirmSeed = "confirm-seed";
+    public const string StepWords = "words";
+    public const string StepPassphrase = "passphrase";
+    public const string StepPassword = "password";
+
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(IsStepStart))]
+    [NotifyPropertyChangedFor(nameof(IsStepOpen))]
+    [NotifyPropertyChangedFor(nameof(IsStepShowSeed))]
+    [NotifyPropertyChangedFor(nameof(IsStepConfirmSeed))]
+    [NotifyPropertyChangedFor(nameof(IsStepWords))]
+    [NotifyPropertyChangedFor(nameof(IsStepPassphrase))]
+    [NotifyPropertyChangedFor(nameof(IsStepPassword))]
+    private string setupStep = StepStart;
+
+    public bool IsStepStart => SetupStep == StepStart;
+    public bool IsStepOpen => SetupStep == StepOpen;
+    public bool IsStepShowSeed => SetupStep == StepShowSeed;
+    public bool IsStepConfirmSeed => SetupStep == StepConfirmSeed;
+    public bool IsStepWords => SetupStep == StepWords;
+    public bool IsStepPassphrase => SetupStep == StepPassphrase;
+    public bool IsStepPassword => SetupStep == StepPassword;
+
+    /// <summary>True quando il flusso è "ripristina" (parole inserite dall'utente).</summary>
+    private bool _isRestoreFlow;
 
     [ObservableProperty]
     private string mnemonicInput = "";
 
+    [ObservableProperty]
+    private string confirmMnemonicInput = "";
+
     [ObservableProperty]
     private string passphraseInput = "";
 
@@ -97,7 +188,7 @@ public partial class MainWindowViewModel : ViewModelBase
     private bool useSsl;
 
     [ObservableProperty]
-    private string connectionStatus = "non connesso";
+    private string connectionStatus = Loc.Tr("conn.none");
 
     [ObservableProperty]
     private bool isConnected;
@@ -162,7 +253,7 @@ public partial class MainWindowViewModel : ViewModelBase
         }
         else if (_autoReconnect)
         {
-            ConnectionStatus = "riconnessione…";
+            ConnectionStatus = Loc.Tr("conn.reconnecting");
             await ConnectAndSync();
         }
     }
@@ -176,10 +267,12 @@ public partial class MainWindowViewModel : ViewModelBase
 
     private void RefreshSetupState()
     {
+        SetupStep = StepStart;
+        MnemonicInput = ConfirmMnemonicInput = PassphraseInput = PasswordInput = "";
         WalletFileExists = WalletStore.Exists(AppPaths.DefaultWalletPath(Net));
         StatusMessage = WalletFileExists
-            ? "Trovato un wallet esistente: inserisci la password (se impostata) e apri."
-            : "Nessun wallet su questa rete: creane uno nuovo o ripristina da seed.";
+            ? Loc.Tr("msg.welcome.existing")
+            : Loc.Tr("msg.welcome.new");
         RefreshServers();
     }
 
@@ -205,13 +298,94 @@ public partial class MainWindowViewModel : ViewModelBase
             ServerInput = $"{server.Host}:{server.PortFor(value)}";
     }
 
-    // ---------- comandi setup ----------
+    // ---------- comandi del wizard (§15): un passo alla volta ----------
 
     [RelayCommand]
-    private void GenerateMnemonic()
+    private void WizardStartOpen()
     {
+        PasswordInput = "";
+        SetupStep = StepOpen;
+        StatusMessage = Loc.Tr("msg.open.password");
+    }
+
+    [RelayCommand]
+    private void WizardStartNew()
+    {
+        _isRestoreFlow = false;
         MnemonicInput = Bip39.Generate(MnemonicLength.Twelve).ToString();
-        StatusMessage = "Nuova mnemonica generata: SCRIVILA SU CARTA prima di continuare.";
+        SetupStep = StepShowSeed;
+        StatusMessage = Loc.Tr("msg.seed.write");
+    }
+
+    [RelayCommand]
+    private void WizardStartRestore()
+    {
+        _isRestoreFlow = true;
+        MnemonicInput = "";
+        SetupStep = StepWords;
+        StatusMessage = Loc.Tr("msg.words.enter");
+    }
+
+    [RelayCommand]
+    private void WizardNextFromShowSeed()
+    {
+        ConfirmMnemonicInput = "";
+        SetupStep = StepConfirmSeed;
+        StatusMessage = Loc.Tr("msg.seed.retype");
+    }
+
+    [RelayCommand]
+    private void WizardNextFromConfirmSeed()
+    {
+        var normalized = string.Join(' ',
+            ConfirmMnemonicInput.Split(' ', StringSplitOptions.RemoveEmptyEntries));
+        if (!string.Equals(normalized, MnemonicInput, StringComparison.OrdinalIgnoreCase))
+        {
+            StatusMessage = Loc.Tr("msg.seed.mismatch");
+            return;
+        }
+        GoToPassphraseStep();
+    }
+
+    [RelayCommand]
+    private void WizardNextFromWords()
+    {
+        if (!Bip39.TryParse(MnemonicInput, out _))
+        {
+            StatusMessage = Loc.Tr("msg.words.invalid");
+            return;
+        }
+        GoToPassphraseStep();
+    }
+
+    private void GoToPassphraseStep()
+    {
+        PassphraseInput = "";
+        SetupStep = StepPassphrase;
+        StatusMessage = Loc.Tr("msg.passphrase.info");
+    }
+
+    [RelayCommand]
+    private void WizardNextFromPassphrase()
+    {
+        PasswordInput = "";
+        SetupStep = StepPassword;
+        StatusMessage = Loc.Tr("msg.password.info");
+    }
+
+    [RelayCommand]
+    private void WizardBack()
+    {
+        SetupStep = SetupStep switch
+        {
+            StepOpen or StepShowSeed or StepWords => StepStart,
+            StepConfirmSeed => StepShowSeed,
+            StepPassphrase => _isRestoreFlow ? StepWords : StepConfirmSeed,
+            StepPassword => StepPassphrase,
+            _ => StepStart,
+        };
+        if (SetupStep == StepStart)
+            RefreshSetupState();
     }
 
     [RelayCommand]
@@ -251,7 +425,7 @@ public partial class MainWindowViewModel : ViewModelBase
         }
         catch (WrongPasswordException)
         {
-            StatusMessage = "Password errata.";
+            StatusMessage = Loc.Tr("msg.wrongpassword");
         }
         catch (Exception ex)
         {
@@ -271,11 +445,13 @@ public partial class MainWindowViewModel : ViewModelBase
         }
         catch (WrongPasswordException)
         {
-            // Cifrato: si chiede la password nel pannello di apertura.
+            // Cifrato: si chiede la password nel passo di apertura del wizard.
             if (IsWalletOpen)
                 CloseWallet();
             _pendingOpenPath = path;
             WalletFileExists = true;
+            PasswordInput = "";
+            SetupStep = StepOpen;
             StatusMessage = $"Il wallet \"{Path.GetFileName(path)}\" è cifrato: inserisci la password e premi Apri.";
         }
         catch (Exception ex)
@@ -291,7 +467,7 @@ public partial class MainWindowViewModel : ViewModelBase
         if (IsWalletOpen)
             CloseWallet();
         _pendingOpenPath = null;
-        StatusMessage = "Crea un nuovo wallet o ripristina da seed. ATTENZIONE: sovrascrive il wallet di default della rete selezionata.";
+        StatusMessage = Loc.Tr("msg.welcome.new");
     }
 
     private void OpenLoaded(WalletDocument doc, HdAccount account, string path, string? password)
@@ -302,15 +478,17 @@ public partial class MainWindowViewModel : ViewModelBase
         _account = account;
         _walletPath = path;
         _password = password;
-        MnemonicInput = PassphraseInput = PasswordInput = "";
+        MnemonicInput = ConfirmMnemonicInput = PassphraseInput = PasswordInput = "";
+        SetupStep = StepStart;
 
         NetworkInfo = $"{doc.Network} · {doc.ScriptKind} · m/{doc.AccountPath}"
             + (doc.IsWatchOnly ? " · watch-only" : "");
         ApplyCache(doc.Cache);
         IsWalletOpen = true;
-        StatusMessage = doc.Cache is null
-            ? "Wallet aperto. Connettiti a un server per sincronizzare."
-            : "Wallet aperto (dati dell'ultima sincronizzazione).";
+        StatusMessage = Loc.Tr("msg.opened");
+        // Come Electrum: ci si connette da soli al server selezionato,
+        // senza aspettare un click.
+        _ = ConnectAndSync();
     }
 
     private void ApplyCache(SyncCache? cache)
@@ -330,20 +508,20 @@ public partial class MainWindowViewModel : ViewModelBase
                     _account.GetReceiveAddress(i).ToString(), "—", "—"));
             return;
         }
-        BalanceText = CoinAmount.Format(cache.ConfirmedSats, Profile.CoinUnit);
+        BalanceText = Fmt(cache.ConfirmedSats);
         // Saldo in attesa: somma delle tx in mempool (può essere negativo per
         // gli invii in uscita non ancora confermati). Non è spendibile finché
         // non conferma: la TransactionFactory usa solo UTXO confermati.
         var pending = cache.History.Where(t => t.Height <= 0).Sum(t => t.DeltaSats);
         UnconfirmedText = pending != 0
-            ? $"in attesa di conferma: {(pending > 0 ? "+" : "")}{CoinAmount.Format(pending)} — non ancora spendibile"
+            ? $"{Loc.Tr("msg.pending")}: {(pending > 0 ? "+" : "")}{Fmt(pending)} — {Loc.Tr("msg.notspendable")}"
             : "";
         ReceiveAddress = _account.GetReceiveAddress(cache.NextReceiveIndex).ToString();
         History.Clear();
         foreach (var tx in cache.History)
             History.Add(new HistoryRow(
                 tx.Height > 0 ? tx.Height.ToString() : "mempool",
-                (tx.DeltaSats >= 0 ? "+" : "") + CoinAmount.Format(tx.DeltaSats),
+                (tx.DeltaSats >= 0 ? "+" : "") + Fmt(tx.DeltaSats, withLabel: false),
                 tx.Txid,
                 tx.Verified ? "✓ SPV" : "—"));
 
@@ -353,7 +531,7 @@ public partial class MainWindowViewModel : ViewModelBase
                 a.IsChange ? "change" : "ricezione",
                 a.Index,
                 a.Address,
-                a.BalanceSats > 0 ? CoinAmount.Format(a.BalanceSats) : (a.TxCount > 0 ? "0" : "—"),
+                a.BalanceSats > 0 ? Fmt(a.BalanceSats, withLabel: false) : (a.TxCount > 0 ? "0" : "—"),
                 a.TxCount > 0 ? a.TxCount.ToString() : "—"));
     }
 
@@ -364,6 +542,11 @@ public partial class MainWindowViewModel : ViewModelBase
     {
         if (_account is null || _doc is null)
             return;
+        if (IsSyncing)
+        {
+            _resyncRequested = true;
+            return;
+        }
         IsSyncing = true;
         StatusMessage = "";
         try
@@ -371,23 +554,30 @@ public partial class MainWindowViewModel : ViewModelBase
             if (_client is null || !_client.IsConnected)
             {
                 var (host, port) = ParseServer();
-                ConnectionStatus = $"connessione a {host}:{port}…";
+                ConnectionStatus = $"{Loc.Tr("conn.connectingto")} {host}:{port}…";
                 var pins = new CertificatePinStore(AppPaths.CertificatePinsPath(Net));
                 _client = await ElectrumClient.ConnectAsync(host, port, UseSsl, pins);
                 _client.NotificationReceived += OnServerNotification;
                 _client.Disconnected += _ => Dispatcher.UIThread.Post(() =>
                 {
                     IsConnected = false;
-                    ConnectionStatus = "disconnesso";
+                    ConnectionStatus = Loc.Tr("conn.disconnected");
                 });
                 IsConnected = true;
                 _autoReconnect = true;
-                ConnectionStatus = $"connesso a {host}:{port}{(UseSsl ? " (TLS)" : "")}";
+                ConnectionStatus = $"{Loc.Tr("conn.connectedto")} {host}:{port}{(UseSsl ? " (TLS)" : "")}";
+                // Synchronizer per connessione: conserva la cache di tx e
+                // prove verificate, così le risincronizzazioni sono incrementali.
+                _synchronizer = new WalletSynchronizer(_account, _client, _doc.GapLimit);
+                _synchronizer.Progress += msg => Dispatcher.UIThread.Post(() => StatusMessage = msg);
             }
 
-            var sync = new WalletSynchronizer(_account, _client, _doc.GapLimit);
-            sync.Progress += msg => Dispatcher.UIThread.Post(() => StatusMessage = msg);
-            var result = await sync.SyncOnceAsync();
+            // Se durante la sync arrivano notifiche, si ripete subito: nessun
+            // aggiornamento del server va perso (modello Electrum).
+            do
+            {
+                _resyncRequested = false;
+                var result = await _synchronizer!.SyncOnceAsync();
                 _lastTransactions = result.Transactions;
 
                 _doc.Cache = new SyncCache
@@ -403,19 +593,20 @@ public partial class MainWindowViewModel : ViewModelBase
                 };
                 WalletStore.Save(_doc, _walletPath!, _password);
                 ApplyCache(_doc.Cache);
-            StatusMessage = $"Sincronizzato: altezza {result.TipHeight}, " +
-                $"{result.History.Count} transazioni verificate SPV.";
+                StatusMessage = $"{Loc.Tr("msg.synced")}: {Loc.Tr("msg.height")} {result.TipHeight}, " +
+                    $"{result.History.Count} {Loc.Tr("msg.synced.detail")}";
+            } while (_resyncRequested);
         }
         catch (CertificatePinMismatchException ex)
         {
             IsConnected = false;
-            ConnectionStatus = "certificato cambiato";
+            ConnectionStatus = Loc.Tr("conn.certchanged");
             StatusMessage = ex.Message;
         }
         catch (Exception ex)
         {
             IsConnected = _client?.IsConnected == true;
-            ConnectionStatus = IsConnected ? ConnectionStatus : "errore di connessione";
+            ConnectionStatus = IsConnected ? ConnectionStatus : Loc.Tr("conn.error");
             StatusMessage = $"Errore: {ex.Message}";
         }
         finally
@@ -430,7 +621,7 @@ public partial class MainWindowViewModel : ViewModelBase
     {
         if (_client is null || !_client.IsConnected)
         {
-            StatusMessage = "Connettiti a un server prima di cercare i peer.";
+            StatusMessage = Loc.Tr("conn.none") + ".";
             return;
         }
         try
@@ -453,10 +644,14 @@ public partial class MainWindowViewModel : ViewModelBase
     private void OnServerNotification(string method, System.Text.Json.JsonElement payload)
     {
         // Cambiamento su un nostro indirizzo o nuovo blocco: risincronizza.
+        // Se una sync è già in corso, si accoda (il loop in ConnectAndSync la
+        // ripete subito dopo): nessuna notifica viene persa.
         if (method is "blockchain.scripthash.subscribe" or "blockchain.headers.subscribe")
             Dispatcher.UIThread.Post(() =>
             {
-                if (!IsSyncing)
+                if (IsSyncing)
+                    _resyncRequested = true;
+                else
                     _ = ConnectAndSync();
             });
     }
@@ -465,7 +660,7 @@ public partial class MainWindowViewModel : ViewModelBase
     private void ResetCertificates()
     {
         new CertificatePinStore(AppPaths.CertificatePinsPath(Net)).ResetAll();
-        StatusMessage = "Certificati SSL azzerati: riprova la connessione.";
+        StatusMessage = Loc.Tr("msg.certreset");
     }
 
     [RelayCommand]
@@ -486,7 +681,7 @@ public partial class MainWindowViewModel : ViewModelBase
 
             var destination = BitcoinAddress.Create(SendTo.Trim(), PalladiumNetworks.For(Net));
             long amount = 0;
-            if (!SendAll && !CoinAmount.TryParseCoins(SendAmount, out amount))
+            if (!SendAll && !CoinAmount.TryParseIn(SendAmount, _config.Unit, out amount))
             {
                 SendPreview = "Importo non valido.";
                 return;
@@ -502,7 +697,7 @@ public partial class MainWindowViewModel : ViewModelBase
                 _doc.Cache.NextChangeIndex, SendAll);
 
             SendPreview = $"txid {_pendingSend.Txid[..16]}… · " +
-                $"fee {CoinAmount.Format(_pendingSend.Fee.Satoshi, Profile.CoinUnit)} " +
+                $"fee {Fmt(_pendingSend.Fee.Satoshi)} " +
                 $"({_pendingSend.Transaction.GetVirtualSize()} vB)" +
                 (_pendingSend.Signed ? "" : " · NON firmata (watch-only)");
             HasPendingSend = _pendingSend.Signed;
@@ -541,6 +736,9 @@ public partial class MainWindowViewModel : ViewModelBase
     {
         _ = _client?.DisposeAsync().AsTask();
         _client = null;
+        _synchronizer = null;
+        _autoReconnect = false;
+        _resyncRequested = false;
         _doc = null;
         _account = null;
         _lastTransactions = null;
@@ -549,7 +747,7 @@ public partial class MainWindowViewModel : ViewModelBase
         History.Clear();
         IsWalletOpen = false;
         IsConnected = false;
-        ConnectionStatus = "non connesso";
+        ConnectionStatus = Loc.Tr("conn.none");
         RefreshSetupState();
     }
 

src/App/Views/MainWindow.axaml

@@ -18,57 +18,145 @@
 
         <!-- ============ MENU (stile Electrum) ============ -->
         <Menu Grid.Row="0">
-            <MenuItem Header="_File">
-                <MenuItem Header="Nuovo / ripristina wallet…" Command="{Binding NewWalletCommand}"/>
-                <MenuItem Header="Apri wallet da file…" Click="OnOpenWalletFileClick"/>
+            <MenuItem Header="{Binding Loc[menu.file]}">
+                <MenuItem Header="{Binding Loc[menu.file.new]}" Command="{Binding NewWalletCommand}"/>
+                <MenuItem Header="{Binding Loc[menu.file.open]}" Click="OnOpenWalletFileClick"/>
                 <Separator/>
-                <MenuItem Header="Chiudi wallet" Command="{Binding CloseWalletCommand}"
+                <MenuItem Header="{Binding Loc[menu.file.close]}" Command="{Binding CloseWalletCommand}"
                           IsEnabled="{Binding IsWalletOpen}"/>
             </MenuItem>
-            <MenuItem Header="_Rete">
-                <MenuItem Header="Cerca altri server (peer)" Command="{Binding DiscoverServersCommand}"/>
-                <MenuItem Header="Reset certificati SSL" Command="{Binding ResetCertificatesCommand}"/>
+            <MenuItem Header="{Binding Loc[menu.net]}">
+                <MenuItem Header="{Binding Loc[menu.net.discover]}" Command="{Binding DiscoverServersCommand}"/>
+                <MenuItem Header="{Binding Loc[menu.net.resetcerts]}" Command="{Binding ResetCertificatesCommand}"/>
+            </MenuItem>
+            <MenuItem Header="{Binding Loc[menu.settings]}">
+                <MenuItem Header="{Binding Loc[settings.language]}">
+                    <MenuItem Header="Italiano" ToggleType="Radio"
+                              IsChecked="{Binding IsLangIt, Mode=OneWay}"
+                              Command="{Binding SetLanguageCommand}" CommandParameter="it"/>
+                    <MenuItem Header="English" ToggleType="Radio"
+                              IsChecked="{Binding IsLangEn, Mode=OneWay}"
+                              Command="{Binding SetLanguageCommand}" CommandParameter="en"/>
+                </MenuItem>
+                <MenuItem Header="{Binding Loc[settings.unit.short]}">
+                    <MenuItem Header="PLM" ToggleType="Radio"
+                              IsChecked="{Binding IsUnitPlm, Mode=OneWay}"
+                              Command="{Binding SetUnitCommand}" CommandParameter="PLM"/>
+                    <MenuItem Header="mPLM" ToggleType="Radio"
+                              IsChecked="{Binding IsUnitMilli, Mode=OneWay}"
+                              Command="{Binding SetUnitCommand}" CommandParameter="mPLM"/>
+                    <MenuItem Header="µPLM" ToggleType="Radio"
+                              IsChecked="{Binding IsUnitMicro, Mode=OneWay}"
+                              Command="{Binding SetUnitCommand}" CommandParameter="µPLM"/>
+                    <MenuItem Header="sat" ToggleType="Radio"
+                              IsChecked="{Binding IsUnitSat, Mode=OneWay}"
+                              Command="{Binding SetUnitCommand}" CommandParameter="sat"/>
+                </MenuItem>
             </MenuItem>
         </Menu>
 
-        <!-- ============ PANNELLO SETUP: crea / ripristina / apri ============ -->
+        <!-- ============ WIZARD DI SETUP (§15): un passo alla volta ============ -->
         <ScrollViewer Grid.Row="1" IsVisible="{Binding IsSetupVisible}">
-            <StackPanel MaxWidth="560" Margin="24" Spacing="14">
-                <TextBlock Text="Palladium Wallet" FontSize="28" FontWeight="Bold"/>
+            <StackPanel MaxWidth="560" Margin="24,40" Spacing="18"
+                        HorizontalAlignment="Center">
+                <TextBlock Text="Palladium Wallet" FontSize="28" FontWeight="Bold"
+                           HorizontalAlignment="Center"/>
 
-                <StackPanel Orientation="Horizontal" Spacing="10">
-                    <TextBlock Text="Rete:" VerticalAlignment="Center"/>
+                <!-- Passo 1: scelta iniziale -->
+                <StackPanel IsVisible="{Binding IsStepStart}" Spacing="12">
+                    <StackPanel Orientation="Horizontal" Spacing="10" HorizontalAlignment="Center">
+                        <TextBlock Text="{Binding Loc[wiz.net]}" VerticalAlignment="Center"/>
                         <ComboBox ItemsSource="{Binding Networks}"
-                              SelectedItem="{Binding SelectedNetwork}"
-                              MinWidth="140"/>
+                                  SelectedItem="{Binding SelectedNetwork}" MinWidth="140"/>
+                    </StackPanel>
+                    <Button Content="{Binding Loc[wiz.open.btn]}" FontSize="16"
+                            HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"
+                            IsVisible="{Binding WalletFileExists}"
+                            Command="{Binding WizardStartOpenCommand}"/>
+                    <Button Content="{Binding Loc[wiz.new.btn]}" FontSize="16"
+                            HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"
+                            Command="{Binding WizardStartNewCommand}"/>
+                    <Button Content="{Binding Loc[wiz.restore.btn]}" FontSize="16"
+                            HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"
+                            Command="{Binding WizardStartRestoreCommand}"/>
                 </StackPanel>
 
-                <!-- Apri wallet esistente -->
-                <Border IsVisible="{Binding WalletFileExists}"
-                        BorderBrush="{DynamicResource SystemAccentColor}" BorderThickness="1"
+                <!-- Passo: password del wallet esistente -->
+                <StackPanel IsVisible="{Binding IsStepOpen}" Spacing="12">
+                    <TextBlock Text="{Binding Loc[wiz.open.title]}" FontSize="18" FontWeight="Bold"/>
+                    <TextBox PlaceholderText="{Binding Loc[wiz.open.placeholder]}"
+                             PasswordChar="●" Text="{Binding PasswordInput}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="10">
+                        <Button Content="{Binding Loc[wiz.back]}" Command="{Binding WizardBackCommand}"/>
+                        <Button Content="{Binding Loc[wiz.open.ok]}" Classes="accent"
+                                Command="{Binding OpenExistingCommand}"/>
+                    </StackPanel>
+                </StackPanel>
+
+                <!-- Passo: mostra il nuovo seed -->
+                <StackPanel IsVisible="{Binding IsStepShowSeed}" Spacing="12">
+                    <TextBlock Text="{Binding Loc[wiz.seed.title]}" FontSize="18" FontWeight="Bold"/>
+                    <Border BorderBrush="{DynamicResource SystemAccentColor}" BorderThickness="1"
                             CornerRadius="6" Padding="14">
-                    <StackPanel Spacing="8">
-                        <TextBlock Text="Apri il wallet esistente" FontWeight="Bold"/>
-                        <TextBox PlaceholderText="Password del file (vuoto se non impostata)"
-                                 PasswordChar="●" Text="{Binding PasswordInput}"/>
-                        <Button Content="Apri wallet" Command="{Binding OpenExistingCommand}"/>
-                    </StackPanel>
+                        <SelectableTextBlock Text="{Binding MnemonicInput}"
+                                             FontFamily="monospace" FontSize="16" TextWrapping="Wrap"/>
                     </Border>
+                    <TextBlock Foreground="Orange" TextWrapping="Wrap"
+                               Text="{Binding Loc[wiz.seed.warning]}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="10">
+                        <Button Content="{Binding Loc[wiz.back]}" Command="{Binding WizardBackCommand}"/>
+                        <Button Content="{Binding Loc[wiz.seed.next]}" Classes="accent"
+                                Command="{Binding WizardNextFromShowSeedCommand}"/>
+                    </StackPanel>
+                </StackPanel>
 
-                <!-- Crea / ripristina -->
-                <Border BorderBrush="Gray" BorderThickness="1" CornerRadius="6" Padding="14">
-                    <StackPanel Spacing="8">
-                        <TextBlock Text="Crea nuovo o ripristina da seed" FontWeight="Bold"/>
-                        <TextBox PlaceholderText="Mnemonica BIP39 (12 o 24 parole)"
-                                 AcceptsReturn="False" Text="{Binding MnemonicInput}"/>
-                        <Button Content="Genera nuova mnemonica" Command="{Binding GenerateMnemonicCommand}"/>
-                        <TextBox PlaceholderText="Passphrase BIP39 opzionale (cambia il wallet! annotala a parte)"
-                                 Text="{Binding PassphraseInput}"/>
-                        <TextBox PlaceholderText="Password di cifratura del file wallet (consigliata)"
-                                 PasswordChar="●" Text="{Binding PasswordInput}"/>
-                        <Button Content="Crea / ripristina wallet" Command="{Binding CreateOrRestoreCommand}"/>
+                <!-- Passo: conferma del seed -->
+                <StackPanel IsVisible="{Binding IsStepConfirmSeed}" Spacing="12">
+                    <TextBlock Text="{Binding Loc[wiz.confirm.title]}" FontSize="18" FontWeight="Bold"/>
+                    <TextBox PlaceholderText="{Binding Loc[wiz.confirm.placeholder]}"
+                             AcceptsReturn="False" Text="{Binding ConfirmMnemonicInput}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="10">
+                        <Button Content="{Binding Loc[wiz.back]}" Command="{Binding WizardBackCommand}"/>
+                        <Button Content="{Binding Loc[wiz.next]}" Classes="accent"
+                                Command="{Binding WizardNextFromConfirmSeedCommand}"/>
+                    </StackPanel>
+                </StackPanel>
+
+                <!-- Passo: inserimento seed (ripristino) -->
+                <StackPanel IsVisible="{Binding IsStepWords}" Spacing="12">
+                    <TextBlock Text="{Binding Loc[wiz.words.title]}" FontSize="18" FontWeight="Bold"/>
+                    <TextBox PlaceholderText="{Binding Loc[wiz.words.placeholder]}"
+                             AcceptsReturn="False" Text="{Binding MnemonicInput}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="10">
+                        <Button Content="{Binding Loc[wiz.back]}" Command="{Binding WizardBackCommand}"/>
+                        <Button Content="{Binding Loc[wiz.next]}" Classes="accent"
+                                Command="{Binding WizardNextFromWordsCommand}"/>
+                    </StackPanel>
+                </StackPanel>
+
+                <!-- Passo: passphrase opzionale -->
+                <StackPanel IsVisible="{Binding IsStepPassphrase}" Spacing="12">
+                    <TextBlock Text="{Binding Loc[wiz.passphrase.title]}" FontSize="18" FontWeight="Bold"/>
+                    <TextBox PlaceholderText="{Binding Loc[wiz.passphrase.placeholder]}"
+                             Text="{Binding PassphraseInput}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="10">
+                        <Button Content="{Binding Loc[wiz.back]}" Command="{Binding WizardBackCommand}"/>
+                        <Button Content="{Binding Loc[wiz.next]}" Classes="accent"
+                                Command="{Binding WizardNextFromPassphraseCommand}"/>
+                    </StackPanel>
+                </StackPanel>
+
+                <!-- Passo finale: password del file -->
+                <StackPanel IsVisible="{Binding IsStepPassword}" Spacing="12">
+                    <TextBlock Text="{Binding Loc[wiz.password.title]}" FontSize="18" FontWeight="Bold"/>
+                    <TextBox PlaceholderText="{Binding Loc[wiz.password.placeholder]}"
+                             PasswordChar="●" Text="{Binding PasswordInput}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="10">
+                        <Button Content="{Binding Loc[wiz.back]}" Command="{Binding WizardBackCommand}"/>
+                        <Button Content="{Binding Loc[wiz.password.create]}" Classes="accent"
+                                Command="{Binding CreateOrRestoreCommand}"/>
+                    </StackPanel>
                 </StackPanel>
-                </Border>
             </StackPanel>
         </ScrollViewer>
 
@@ -82,7 +170,7 @@
                     <TextBlock Text="{Binding UnconfirmedText}" Foreground="Orange"/>
                     <TextBlock Text="{Binding NetworkInfo}" FontSize="12" Foreground="Gray"/>
                 </StackPanel>
-                <Button Grid.Column="1" Content="Chiudi wallet" VerticalAlignment="Top"
+                <Button Grid.Column="1" Content="{Binding Loc[wallet.close]}" VerticalAlignment="Top"
                         Command="{Binding CloseWalletCommand}"/>
             </Grid>
 
@@ -90,7 +178,7 @@
             <Border Grid.Row="1" Margin="0,12,0,12" Padding="10"
                     BorderBrush="Gray" BorderThickness="1" CornerRadius="6">
                 <Grid RowDefinitions="Auto,Auto" ColumnDefinitions="Auto,*,Auto,Auto">
-                    <TextBlock Grid.Row="0" Grid.Column="0" Text="Server:"
+                    <TextBlock Grid.Row="0" Grid.Column="0" Text="{Binding Loc[wallet.server]}"
                                VerticalAlignment="Center" Margin="0,0,8,0"/>
                     <ComboBox Grid.Row="0" Grid.Column="1"
                               ItemsSource="{Binding KnownServers}"
@@ -98,16 +186,16 @@
                               HorizontalAlignment="Stretch"/>
                     <CheckBox Grid.Row="0" Grid.Column="2" Content="TLS"
                               IsChecked="{Binding UseSsl}" Margin="8,0"/>
-                    <Button Grid.Row="0" Grid.Column="3" Content="Connetti e sincronizza"
+                    <Button Grid.Row="0" Grid.Column="3" Content="{Binding Loc[wallet.connect]}"
                             Command="{Binding ConnectAndSyncCommand}" IsEnabled="{Binding !IsSyncing}"/>
 
                     <StackPanel Grid.Row="1" Grid.Column="1" Orientation="Horizontal"
                                 Spacing="8" Margin="0,8,0,0">
                         <TextBox Text="{Binding ServerInput}" MinWidth="220"
-                                 PlaceholderText="oppure host:porta manuale"/>
-                        <Button Content="Cerca altri server"
+                                 PlaceholderText="{Binding Loc[wallet.manual]}"/>
+                        <Button Content="{Binding Loc[wallet.discover]}"
                                 Command="{Binding DiscoverServersCommand}"/>
-                        <Button Content="Reset cert."
+                        <Button Content="{Binding Loc[wallet.resetcert]}"
                                 Command="{Binding ResetCertificatesCommand}"/>
                     </StackPanel>
                     <StackPanel Grid.Row="1" Grid.Column="2" Grid.ColumnSpan="2"
@@ -122,19 +210,19 @@
                 </Grid>
             </Border>
 
-            <!-- Tab: Ricevi / Storico / Invia -->
+            <!-- Tab: Ricevi / Storico / Indirizzi / Invia -->
             <TabControl Grid.Row="2">
-                <TabItem Header="Ricevi">
+                <TabItem Header="{Binding Loc[tab.receive]}">
                     <StackPanel Spacing="10" Margin="8">
-                        <TextBlock Text="Prossimo indirizzo non usato:"/>
+                        <TextBlock Text="{Binding Loc[receive.next]}"/>
                         <SelectableTextBlock Text="{Binding ReceiveAddress}"
                                              FontFamily="monospace" FontSize="16"/>
-                        <TextBlock Text="Ogni pagamento ricevuto qui comparirà nello storico alla prossima sincronizzazione."
+                        <TextBlock Text="{Binding Loc[receive.hint]}"
                                    Foreground="Gray" FontSize="12" TextWrapping="Wrap"/>
                     </StackPanel>
                 </TabItem>
 
-                <TabItem Header="Storico">
+                <TabItem Header="{Binding Loc[tab.history]}">
                     <ListBox ItemsSource="{Binding History}" Margin="4">
                         <ListBox.ItemTemplate>
                             <DataTemplate x:DataType="vm:HistoryRow">
@@ -150,13 +238,13 @@
                     </ListBox>
                 </TabItem>
 
-                <TabItem Header="Indirizzi">
+                <TabItem Header="{Binding Loc[tab.addresses]}">
                     <Grid RowDefinitions="Auto,*" Margin="4">
                         <Grid Grid.Row="0" ColumnDefinitions="90,60,*,140,60" Margin="12,4">
-                            <TextBlock Grid.Column="0" Text="Tipo" FontWeight="Bold"/>
-                            <TextBlock Grid.Column="1" Text="Indice" FontWeight="Bold"/>
-                            <TextBlock Grid.Column="2" Text="Indirizzo" FontWeight="Bold"/>
-                            <TextBlock Grid.Column="3" Text="Saldo" FontWeight="Bold"/>
+                            <TextBlock Grid.Column="0" Text="{Binding Loc[addr.type]}" FontWeight="Bold"/>
+                            <TextBlock Grid.Column="1" Text="{Binding Loc[addr.index]}" FontWeight="Bold"/>
+                            <TextBlock Grid.Column="2" Text="{Binding Loc[addr.address]}" FontWeight="Bold"/>
+                            <TextBlock Grid.Column="3" Text="{Binding Loc[addr.balance]}" FontWeight="Bold"/>
                             <TextBlock Grid.Column="4" Text="Tx" FontWeight="Bold"/>
                         </Grid>
                         <ListBox Grid.Row="1" ItemsSource="{Binding Addresses}">
@@ -176,23 +264,25 @@
                     </Grid>
                 </TabItem>
 
-                <TabItem Header="Invia">
+                <TabItem Header="{Binding Loc[tab.send]}">
                     <StackPanel Spacing="10" Margin="8" MaxWidth="640" HorizontalAlignment="Left">
-                        <TextBox PlaceholderText="Indirizzo destinatario" Text="{Binding SendTo}"
+                        <TextBox PlaceholderText="{Binding Loc[send.to]}" Text="{Binding SendTo}"
                                  FontFamily="monospace"/>
-                        <Grid ColumnDefinitions="*,Auto,Auto">
-                            <TextBox Grid.Column="0" PlaceholderText="Importo (es. 1.5)"
+                        <Grid ColumnDefinitions="*,Auto,Auto,Auto">
+                            <TextBox Grid.Column="0" PlaceholderText="{Binding Loc[send.amount]}"
                                      Text="{Binding SendAmount}" IsEnabled="{Binding !SendAll}"/>
-                            <CheckBox Grid.Column="1" Content="Invia tutto" Margin="10,0"
+                            <TextBlock Grid.Column="1" Text="{Binding UnitLabel}"
+                                       VerticalAlignment="Center" Margin="6,0" Foreground="Gray"/>
+                            <CheckBox Grid.Column="2" Content="{Binding Loc[send.all]}" Margin="10,0"
                                       IsChecked="{Binding SendAll}"/>
-                            <StackPanel Grid.Column="2" Orientation="Horizontal" Spacing="6">
-                                <TextBlock Text="fee sat/vB:" VerticalAlignment="Center"/>
+                            <StackPanel Grid.Column="3" Orientation="Horizontal" Spacing="6">
+                                <TextBlock Text="{Binding Loc[send.feerate]}" VerticalAlignment="Center"/>
                                 <TextBox Text="{Binding SendFeeRate}" MinWidth="60"/>
                             </StackPanel>
                         </Grid>
                         <StackPanel Orientation="Horizontal" Spacing="10">
-                            <Button Content="Prepara transazione" Command="{Binding PrepareSendCommand}"/>
-                            <Button Content="CONFERMA E TRASMETTI" Classes="accent"
+                            <Button Content="{Binding Loc[send.prepare]}" Command="{Binding PrepareSendCommand}"/>
+                            <Button Content="{Binding Loc[send.confirm]}" Classes="accent"
                                     Command="{Binding ConfirmSendCommand}"
                                     IsEnabled="{Binding HasPendingSend}"/>
                         </StackPanel>

src/Core/Spv/WalletSynchronizer.cs

@@ -40,6 +40,13 @@ public sealed class WalletSynchronizer(HdAccount account, ElectrumClient client,
     /// <summary>Avanzamento leggibile (per CLI e barra di stato GUI).</summary>
     public event Action<string>? Progress;
 
+    // Cache tra le passate (stesso synchronizer per tutta la vita della
+    // connessione): le tx già scaricate e le prove di Merkle già verificate a
+    // una data altezza non si rifanno — le risincronizzazioni da notifica
+    // costano solo ciò che è cambiato (modello Electrum).
+    private readonly Dictionary<string, Transaction> _txCache = [];
+    private readonly Dictionary<string, int> _verifiedAtHeight = [];
+
     public async Task<SyncResult> SyncOnceAsync(CancellationToken ct = default)
     {
         var tip = await client.SubscribeHeadersAsync(ct);
@@ -56,37 +63,45 @@ public sealed class WalletSynchronizer(HdAccount account, ElectrumClient client,
         foreach (var item in historyByAddress.Values.SelectMany(h => h))
             txHeights[item.TxHash] = item.Height;
 
-        // 4. Scarica le transazioni.
-        Progress?.Invoke($"scarico {txHeights.Count} transazioni…");
+        // 4. Scarica in parallelo le sole transazioni nuove.
         var network = PalladiumNetworks.For(account.Profile.Kind);
-        var transactions = new Dictionary<string, Transaction>();
-        foreach (var txid in txHeights.Keys)
+        var missing = txHeights.Keys.Where(txid => !_txCache.ContainsKey(txid)).ToList();
+        if (missing.Count > 0)
         {
-            var hex = await client.GetTransactionAsync(txid, ct);
-            transactions[txid] = Transaction.Parse(hex, network);
+            Progress?.Invoke($"scarico {missing.Count} transazioni…");
+            var downloaded = await Task.WhenAll(missing.Select(async txid =>
+                (txid, Transaction.Parse(await client.GetTransactionAsync(txid, ct), network))));
+            foreach (var (txid, tx) in downloaded)
+                _txCache[txid] = tx;
         }
+        var transactions = txHeights.Keys.ToDictionary(txid => txid, txid => _txCache[txid]);
 
-        // 5. Verifica Merkle delle confermate (§7.4 punto 4).
-        var verified = new Dictionary<string, bool>();
-        foreach (var (txid, height) in txHeights)
+        // 5. Verifica Merkle delle confermate (§7.4 punto 4), in parallelo e
+        //    solo per le tx non ancora verificate a quell'altezza.
+        var toVerify = txHeights
+            .Where(kv => kv.Value > 0
+                && (!_verifiedAtHeight.TryGetValue(kv.Key, out var h) || h != kv.Value))
+            .ToList();
+        if (toVerify.Count > 0)
         {
-            if (height <= 0)
+            Progress?.Invoke($"verifico {toVerify.Count} prove di Merkle…");
+            await Task.WhenAll(toVerify.Select(async kv =>
             {
-                verified[txid] = false; // in mempool: nessuna prova possibile
-                continue;
-            }
-            var proof = await client.GetMerkleAsync(txid, height, ct);
-            var header = BlockHeaderInfo.Parse(await client.GetBlockHeaderAsync(height, ct));
-            var ok = MerkleProof.Verify(
-                uint256.Parse(txid),
-                proof.Pos,
-                proof.Merkle.Select(uint256.Parse),
-                header.MerkleRoot);
-            if (!ok)
+                var (txid, height) = kv;
+                var proofTask = client.GetMerkleAsync(txid, height, ct);
+                var headerTask = client.GetBlockHeaderAsync(height, ct);
+                var proof = await proofTask;
+                var header = BlockHeaderInfo.Parse(await headerTask);
+                if (!MerkleProof.Verify(
+                        uint256.Parse(txid), proof.Pos,
+                        proof.Merkle.Select(uint256.Parse), header.MerkleRoot))
                     throw new SpvVerificationException(
                         $"Prova di Merkle non valida per {txid} (blocco {height}): server non affidabile.");
-            verified[txid] = true;
+            }));
+            foreach (var (txid, height) in toVerify)
+                _verifiedAtHeight[txid] = height;
         }
+        var verified = txHeights.ToDictionary(kv => kv.Key, kv => kv.Value > 0);
 
         // 6. Ricostruzione locale degli UTXO: accrediti = output verso nostri
         //    script; spesi = outpoint consumati da una qualunque tx del wallet.
@@ -179,7 +194,9 @@ public sealed class WalletSynchronizer(HdAccount account, ElectrumClient client,
 
     /// <summary>
     /// Scansiona una catena (receiving o change) finché trova gapLimit indirizzi
-    /// vuoti consecutivi (§5). Ritorna il primo indice non usato.
+    /// vuoti consecutivi (§5), procedendo a batch paralleli di gapLimit
+    /// subscribe per volta (le richieste JSON-RPC sono pipelinabili).
+    /// Ritorna il primo indice non usato.
     /// </summary>
     private async Task<int> ScanChainAsync(bool isChange, List<TrackedAddress> tracked,
         Dictionary<string, IReadOnlyList<HistoryItem>> historyByAddress, CancellationToken ct)
@@ -187,23 +204,38 @@ public sealed class WalletSynchronizer(HdAccount account, ElectrumClient client,
         var consecutiveEmpty = 0;
         var index = 0;
         var firstUnused = 0;
-        for (; consecutiveEmpty < gapLimit; index++)
+        while (consecutiveEmpty < gapLimit)
         {
-            var address = account.GetAddress(isChange, index);
-            var scripthash = Scripthash.FromAddress(address);
-            tracked.Add(new TrackedAddress(address, scripthash, isChange, index));
+            var batch = Enumerable.Range(index, gapLimit).Select(i =>
+            {
+                var address = account.GetAddress(isChange, i);
+                return new TrackedAddress(address, Scripthash.FromAddress(address), isChange, i);
+            }).ToList();
+            index += batch.Count;
+            tracked.AddRange(batch);
 
             // La subscribe registra anche la notifica push per i cambi futuri.
-            var status = await client.SubscribeScripthashAsync(scripthash, ct);
-            if (status is null)
+            var statuses = await Task.WhenAll(
+                batch.Select(t => client.SubscribeScripthashAsync(t.ScriptHash, ct)));
+
+            var used = batch.Where((t, i) => statuses[i] is not null).ToList();
+            var histories = await Task.WhenAll(
+                used.Select(t => client.GetHistoryAsync(t.ScriptHash, ct)));
+            for (var i = 0; i < used.Count; i++)
+                historyByAddress[used[i].ScriptHash] = histories[i];
+
+            for (var i = 0; i < batch.Count && consecutiveEmpty < gapLimit; i++)
+            {
+                if (statuses[i] is null)
                 {
                     consecutiveEmpty++;
-                continue;
                 }
-
-            historyByAddress[scripthash] = await client.GetHistoryAsync(scripthash, ct);
+                else
+                {
                     consecutiveEmpty = 0;
-            firstUnused = index + 1;
+                    firstUnused = batch[i].Index + 1;
+                }
+            }
         }
         return firstUnused;
     }

src/Core/Storage/AppConfig.cs

@@ -0,0 +1,42 @@
+using System.Text.Json;
+
+namespace PalladiumWallet.Core.Storage;
+
+/// <summary>
+/// Configurazione globale dell'applicazione (blueprint §8), separata dai file
+/// wallet: lingua, unità di visualizzazione, ecc. Persistita in config.json
+/// nella radice dei dati (vale per tutte le reti).
+/// </summary>
+public sealed class AppConfig
+{
+    /// <summary>Codice lingua UI ("it", "en").</summary>
+    public string Language { get; set; } = "it";
+
+    /// <summary>Unità di visualizzazione degli importi (vedi <see cref="Wallet.CoinAmount.Units"/>).</summary>
+    public string Unit { get; set; } = "PLM";
+
+    private static readonly JsonSerializerOptions JsonOptions = new() { WriteIndented = true };
+
+    public static AppConfig Load(string? path = null)
+    {
+        path ??= AppPaths.ConfigPath();
+        if (!File.Exists(path))
+            return new AppConfig();
+        try
+        {
+            return JsonSerializer.Deserialize<AppConfig>(File.ReadAllText(path)) ?? new AppConfig();
+        }
+        catch (JsonException)
+        {
+            // Config corrotta: si riparte dai default senza bloccare l'avvio.
+            return new AppConfig();
+        }
+    }
+
+    public void Save(string? path = null)
+    {
+        path ??= AppPaths.ConfigPath();
+        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
+        File.WriteAllText(path, JsonSerializer.Serialize(this, JsonOptions));
+    }
+}

src/Core/Wallet/CoinAmount.cs

@@ -10,10 +10,51 @@ public static class CoinAmount
 {
     public const long SatsPerCoin = 100_000_000;
 
+    /// <summary>Unità di visualizzazione selezionabili (config §8).</summary>
+    public static readonly string[] Units = ["PLM", "mPLM", "µPLM", "sat"];
+
+    /// <summary>(satoshi per unità, decimali mostrati) di ciascuna unità.</summary>
+    private static (long Factor, int Decimals) Of(string unit) => unit switch
+    {
+        "mPLM" => (100_000, 5),
+        "µPLM" => (100, 2),
+        "sat" => (1, 0),
+        _ => (SatsPerCoin, 8), // PLM
+    };
+
     public static string Format(long sats, string unit = "") =>
         (sats / (decimal)SatsPerCoin).ToString("0.00000000", CultureInfo.InvariantCulture)
         + (unit.Length > 0 ? " " + unit : "");
 
+    /// <summary>Formatta nell'unità scelta (es. 150000 sat → "1.50000 mPLM").</summary>
+    public static string FormatIn(long sats, string unit, bool withLabel = true)
+    {
+        var (factor, decimals) = Of(unit);
+        var value = (sats / (decimal)factor).ToString(
+            decimals == 0 ? "0" : "0." + new string('0', decimals), CultureInfo.InvariantCulture);
+        return withLabel ? $"{value} {unit}" : value;
+    }
+
+    /// <summary>Parsa un importo espresso nell'unità scelta in satoshi.</summary>
+    public static bool TryParseIn(string text, string unit, out long sats)
+    {
+        sats = 0;
+        var (factor, _) = Of(unit);
+        text = text.Trim().Replace(',', '.');
+        if (!decimal.TryParse(text, NumberStyles.Number, CultureInfo.InvariantCulture, out var value)
+            || value < 0)
+            return false;
+        try
+        {
+            sats = (long)(value * factor);
+        }
+        catch (OverflowException)
+        {
+            return false;
+        }
+        return true;
+    }
+
     /// <summary>Parsa un importo in coin (punto o virgola decimale) in satoshi.</summary>
     public static bool TryParseCoins(string text, out long sats)
     {

tests/PalladiumWallet.Tests/Wallet/TransactionFactoryTests.cs

@@ -156,4 +156,53 @@ public class TransactionFactoryTests
         Assert.False(CoinAmount.TryParseCoins("abc", out _));
         Assert.False(CoinAmount.TryParseCoins("-1", out _));
     }
+
+    // 1.5 PLM = 150_000_000 sat, espressi in ciascuna unità (§8).
+    [Theory]
+    [InlineData("PLM", "1.50000000 PLM", "1.5")]
+    [InlineData("mPLM", "1500.00000 mPLM", "1500")]
+    [InlineData("µPLM", "1500000.00 µPLM", "1500000")]
+    [InlineData("sat", "150000000 sat", "150000000")]
+    public void Le_unita_formattano_e_parsano_in_modo_coerente(string unit, string formatted, string input)
+    {
+        const long sats = 150_000_000;
+        Assert.Equal(formatted, CoinAmount.FormatIn(sats, unit));
+        Assert.True(CoinAmount.TryParseIn(input, unit, out var parsed));
+        Assert.Equal(sats, parsed);
+    }
+
+    [Fact]
+    public void La_config_globale_fa_roundtrip_su_file()
+    {
+        var path = Path.Combine(Path.GetTempPath(), $"plm-config-{Guid.NewGuid()}.json");
+        try
+        {
+            var config = new PalladiumWallet.Core.Storage.AppConfig { Language = "en", Unit = "sat" };
+            config.Save(path);
+            var loaded = PalladiumWallet.Core.Storage.AppConfig.Load(path);
+            Assert.Equal("en", loaded.Language);
+            Assert.Equal("sat", loaded.Unit);
+        }
+        finally
+        {
+            File.Delete(path);
+        }
+    }
+
+    [Fact]
+    public void Una_config_corrotta_torna_ai_default()
+    {
+        var path = Path.Combine(Path.GetTempPath(), $"plm-config-{Guid.NewGuid()}.json");
+        try
+        {
+            File.WriteAllText(path, "{ rotto ");
+            var loaded = PalladiumWallet.Core.Storage.AppConfig.Load(path);
+            Assert.Equal("it", loaded.Language);
+            Assert.Equal("PLM", loaded.Unit);
+        }
+        finally
+        {
+            File.Delete(path);
+        }
+    }
 }