Desktop: put the keyboard in the closed vault's card on launch, and let Enter sign in and enrol

src/DodoSSH.Client.App/Views/MainWindow.axaml

@@ -383,7 +383,12 @@
                 not replayed. See MainWindow.axaml.cs.
               -->
               <TextBox x:Name="ServerUrlBox" Text="{Binding ServerUrl}"
-                       PlaceholderText="https://dodossh.example" />
+                       PlaceholderText="https://dodossh.example">
+                <!-- Enter signs in, as it unlocks on the unlock card. -->
+                <TextBox.KeyBindings>
+                  <KeyBinding Gesture="Enter" Command="{Binding SignInCommand}" />
+                </TextBox.KeyBindings>
+              </TextBox>
               <Button Classes="accent" Content="SIGN IN WITH YOUR BROWSER" Command="{Binding SignInCommand}"
                       IsEnabled="{Binding !IsBusy}" HorizontalAlignment="Left" />
               <TextBlock Classes="hint" Text="{Binding StatusMessage}" />
@@ -395,8 +400,14 @@
               <TextBlock Classes="heading" Text="Choose a keychain passphrase" />
               <TextBlock Classes="hint"
                          Text="This passphrase never leaves this machine, and the server cannot reset it. It is the only thing standing between a stolen copy of the database and every credential in your keychain." />
-              <TextBox Text="{Binding Passphrase}" PlaceholderText="passphrase" PasswordChar="•" />
-              <TextBox Text="{Binding ConfirmPassphrase}" PlaceholderText="again" PasswordChar="•" />
+              <TextBox x:Name="NewPassphraseBox" Text="{Binding Passphrase}" PlaceholderText="passphrase"
+                       PasswordChar="•" />
+              <TextBox Text="{Binding ConfirmPassphrase}" PlaceholderText="again" PasswordChar="•">
+                <!-- On the second box only: Enter in the first moves nowhere useful, Enter here is "done". -->
+                <TextBox.KeyBindings>
+                  <KeyBinding Gesture="Enter" Command="{Binding EnrollCommand}" />
+                </TextBox.KeyBindings>
+              </TextBox>
               <Button Classes="accent" Content="CREATE MY KEYCHAIN" Command="{Binding EnrollCommand}"
                       IsEnabled="{Binding !IsBusy}" HorizontalAlignment="Left" />
               <TextBlock Classes="hint" Text="{Binding StatusMessage}" />

src/DodoSSH.Client.App/Views/MainWindow.axaml.cs

@@ -33,6 +33,9 @@ internal sealed partial class MainWindow : Window
 
     private bool wasUnlocked;
 
+    /// <summary>Which closed-vault card the keyboard was last sent to, so it is sent once per card.</summary>
+    private ShellState? closedState;
+
     public MainWindow()
     {
         InitializeComponent();
@@ -184,6 +187,7 @@ internal sealed partial class MainWindow : Window
     {
         ShellState.Locked => UnlockPane.PassphraseBox,
         ShellState.NeedsServer => ServerUrlBox,
+        ShellState.NeedsEnrollment => NewPassphraseBox,
         _ => this,
     };
 
@@ -307,6 +311,14 @@ internal sealed partial class MainWindow : Window
         Terminal.Source = viewModel.TerminalPageUrl;
 
         wasUnlocked = viewModel.IsUnlocked;
+        closedState = null;
+
+        // The shell may have reached its card before this window was given it, and then no change would
+        // ever say so.
+        if (!viewModel.IsUnlocked)
+        {
+            FocusClosedVaultCard(viewModel);
+        }
 
         viewModel.TerminalSessionOpened += OnTerminalSessionOpened;
         viewModel.TerminalFocusRequested += OnTerminalFocusRequested;
@@ -380,10 +392,32 @@ internal sealed partial class MainWindow : Window
         {
             ReleaseKeyboardTo(ClosedVaultKeyboardHome);
         }
+        else if (!unlocked && viewModel.State != closedState)
+        {
+            FocusClosedVaultCard(viewModel);
+        }
 
+        closedState = unlocked ? null : viewModel.State;
         wasUnlocked = unlocked;
     }
 
+    /// <summary>Hands the keyboard to the box on whichever card a closed vault is showing.</summary>
+    /// <remarks>
+    /// For arriving at a card other than by locking — launch landing on the unlock card, a sign-in finishing
+    /// on the enrolment one — which used to leave the passphrase somebody started typing going nowhere. Once
+    /// per card, which is what keeps it from moving the keyboard while somebody is mid-sign-in: IsUnlocked is
+    /// raised for every state change, and the state does not change while they type. Posted, because the card
+    /// is revealed by a binding the same change has not reached yet.
+    /// </remarks>
+    private void FocusClosedVaultCard(MainWindowViewModel viewModel)
+    {
+        closedState = viewModel.State;
+
+        var home = ClosedVaultKeyboardHome;
+
+        Dispatcher.UIThread.Post(() => home.Focus(), DispatcherPriority.Loaded);
+    }
+
     /// <remarks>
     /// Closing only. Opening also has to move the keyboard — the palette is a text box somebody is expected
     /// to start typing into immediately — but the palette does that for itself when it becomes visible,

tests/DodoSSH.Client.App.Layout.Tests/ClosedVaultFocusTests.cs

@@ -0,0 +1,127 @@
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Threading;
+using DodoSSH.Client.App.Views;
+using DodoSSH.Client.Session;
+using DodoSSH.Client.Session.Tests;
+using DodoSSH.Client.Shell.ViewModels;
+using DodoSSH.Client.Ssh;
+using DodoSSH.Client.Storage;
+using DodoSSH.Client.Terminal;
+using DodoSSH.Client.Transfer;
+using DodoSSH.Crypto;
+using NSubstitute;
+
+namespace DodoSSH.Client.App.Layout.Tests;
+
+/// <summary>
+/// The keyboard on the cards a closed vault shows: where it is when the card appears, and what Enter does.
+/// </summary>
+/// <remarks>
+/// <para>
+/// Launch used to leave the keyboard nowhere. Focus only moved on the way out of an unlocked vault, so the
+/// passphrase somebody started typing the moment the window appeared went nowhere until they clicked the box,
+/// and Enter in the server address did nothing at all.
+/// </para>
+/// <para>
+/// The whole window, which <see cref="LayoutHarnessTests.WhyTheWindowItselfIsNeverShown"/> says cannot be shown
+/// here: the terminal's WebView refuses this thread's apartment when it is attached. It is taken out of the
+/// tree before the window is shown, which is everything that test is about and nothing these are.
+/// </para>
+/// </remarks>
+public sealed class ClosedVaultFocusTests
+{
+    private const string Passphrase = "a sufficiently long passphrase";
+
+    private static readonly Argon2Profile CheapProfile =
+        Argon2Profile.FromStoredParameters(memoryKibibytes: 8 * 1024, passes: 1, parallelism: 1);
+
+    private static CancellationToken Token => TestContext.Current.CancellationToken;
+
+    [Fact]
+    public async Task AFreshMachine_PutsTheKeyboardInTheServerAddressAndEnterSignsIn()
+    {
+        using var caches = ClientCacheFactory.ForMemory($"focus-{Guid.CreateVersion7():N}");
+        await caches.MigrateAsync(Token);
+
+        await using var workspace = Workspace();
+        await using var shell = Shell(caches, workspace);
+
+        await shell.StartAsync(Token);
+        shell.State.ShouldBe(ShellState.NeedsServer);
+
+        await LayoutHarness.OnTheUiThreadAsync(
+            () => WithWindow(shell, window =>
+            {
+                var box = window.FindControl<TextBox>("ServerUrlBox").ShouldNotBeNull();
+
+                window.FocusManager!.GetFocusedElement().ShouldBeSameAs(box);
+
+                box.KeyBindings.ShouldContain(binding =>
+                    binding.Gesture == new KeyGesture(Key.Enter) && binding.Command == shell.SignInCommand);
+            }),
+            Token);
+    }
+
+    [Fact]
+    public async Task AnEnrolledMachine_PutsTheKeyboardInThePassphraseBox()
+    {
+        using var caches = ClientCacheFactory.ForMemory($"focus-{Guid.CreateVersion7():N}");
+        await caches.MigrateAsync(Token);
+
+        await new AccountProvisioner(new FakeAccountServer(), new StubKeyBinding(), caches, TimeProvider.System, CheapProfile)
+            .EnrollAsync("https://dodossh.example", Passphrase, "laptop", "Personal", Token);
+
+        await using var workspace = Workspace();
+        await using var shell = Shell(caches, workspace);
+
+        await shell.StartAsync(Token);
+        shell.State.ShouldBe(ShellState.Locked);
+
+        await LayoutHarness.OnTheUiThreadAsync(
+            () => WithWindow(shell, window =>
+                window.FocusManager!.GetFocusedElement()
+                    .ShouldBeSameAs(window.FindControl<UnlockCard>("UnlockPane").ShouldNotBeNull().PassphraseBox)),
+            Token);
+    }
+
+    private static TerminalWorkspace Workspace() =>
+        new(
+            new InMemoryTerminalAssetProvider(new Dictionary<string, TerminalAsset>(StringComparer.Ordinal)),
+            Substitute.For<ISshConnectionFactory>(),
+            TimeProvider.System);
+
+    private static MainWindowViewModel Shell(ClientCacheFactory caches, TerminalWorkspace workspace) =>
+        new(
+            new ClientPaths(Path.Combine(Path.GetTempPath(), $"dodossh-focus-{Guid.CreateVersion7():N}")),
+            caches,
+            workspace,
+            new VaultKnownHostStore(),
+            new UnavailableDeviceKeyStore(),
+            static (_, _) => throw new InvalidOperationException("A layout test has no network."),
+            TimeProvider.System,
+            Substitute.For<ISftpSessionFactory>(),
+            CheapProfile);
+
+    private static void WithWindow(MainWindowViewModel shell, Action<MainWindow> assert)
+    {
+        var window = new MainWindow { DataContext = shell };
+
+        if (window.FindControl<NativeWebView>("Terminal") is { Parent: Panel panel } web)
+        {
+            panel.Children.Remove(web);
+        }
+
+        try
+        {
+            LayoutHarness.Settle(window, LayoutHarness.MinimumWidth, LayoutHarness.MinimumHeight);
+            Dispatcher.UIThread.RunJobs();
+
+            assert(window);
+        }
+        finally
+        {
+            window.Close();
+        }
+    }
+}