fix(welcome): notify wizard host on AccountStep validity change so Next enables (live e2e blocker) + regression test

AccountStep now exposes OnValidityChanged EventCallback<bool> and fires it at the end of every Validate() call (including OnInitialized). Routes.razor drops the @ref/IsValid polling pattern in favour of _accountValid updated via the callback + StateHasChanged, matching the existing OnRunningChanged pattern used by ApplyStep. Adds 5 bUnit regression tests covering: initial-invalid, all-valid, re-invalid on clear, short/non-numeric PIN, and pre-populated state on Back→Forward re-mount.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

windows/welcome/src/SilverOS.Welcome.UI/Components/Routes.razor

@@ -40,7 +40,7 @@
                     <FlavourStep Flavours="_flavours" />
                     break;
                 case 2:
-                    <AccountStep @ref="_accountStep" />
+                    <AccountStep OnValidityChanged="@(v => { _accountValid = v; StateHasChanged(); })" />
                     break;
                 case 3:
                     <PrefsStep />
@@ -82,14 +82,14 @@
     private int _currentStep = 0;
     private bool _loading = true;
     private bool _applyRunning = false;
+    private bool _accountValid = false;
     private string? _error;
     private IReadOnlyList<FlavourManifest> _flavours = Array.Empty<FlavourManifest>();
-    private AccountStep? _accountStep;
 
     private bool CanGoNext => _currentStep switch
     {
         1 => State.Flavour is not null,
-        2 => _accountStep?.IsValid ?? false,
+        2 => _accountValid,
         _ => true
     };
 

windows/welcome/src/SilverOS.Welcome.UI/Components/Steps/AccountStep.razor

@@ -1,6 +1,7 @@
 @inject WizardState State
 
 <div class="step account-step">
+
     <h1>Set Up Your Account</h1>
     <p class="step-subtitle">Create your daily-use account and administrator credentials.</p>
 
@@ -53,7 +54,10 @@
     private readonly Dictionary<string, string> _errors = new();
     private readonly HashSet<string> _touched = new();
 
-    /// <summary>True when all fields are valid. Used by the wizard host to gate Next.</summary>
+    /// <summary>Notifies the wizard host whenever validity changes (and on initial mount).</summary>
+    [Parameter] public EventCallback<bool> OnValidityChanged { get; set; }
+
+    /// <summary>True when all fields are valid.</summary>
     public bool IsValid { get; private set; }
 
     protected override void OnInitialized() => Validate();
@@ -81,5 +85,6 @@
             _errors["bitlockerpin"] = "BitLocker PIN must be all digits and at least 6 digits long.";
 
         IsValid = _errors.Count == 0;
+        _ = OnValidityChanged.InvokeAsync(IsValid);
     }
 }

windows/welcome/tests/SilverOS.Welcome.Tests/AccountStepTests.cs

@@ -0,0 +1,103 @@
+using Bunit;
+using Microsoft.AspNetCore.Components;
+using Microsoft.Extensions.DependencyInjection;
+using SilverOS.Welcome.App.Components;
+using SilverOS.Welcome.App.Components.Steps;
+using Xunit;
+
+public class AccountStepTests : TestContext
+{
+    // Helper: register WizardState and render AccountStep with an OnValidityChanged capture.
+    private (IRenderedComponent<AccountStep> cut, Func<bool?> lastValidity) RenderStep(WizardState? state = null)
+    {
+        var wizardState = state ?? new WizardState();
+        Services.AddSingleton(wizardState);
+
+        bool? captured = null;
+        var cut = RenderComponent<AccountStep>(p =>
+            p.Add(s => s.OnValidityChanged,
+                  EventCallback.Factory.Create<bool>(this, v => captured = v)));
+
+        return (cut, () => captured);
+    }
+
+    [Fact]
+    public void OnValidityChanged_fires_false_on_initial_mount_with_empty_fields()
+    {
+        var (_, lastValidity) = RenderStep();
+
+        Assert.NotNull(lastValidity());
+        Assert.False(lastValidity(), "Step should be invalid on first mount (empty fields).");
+    }
+
+    [Fact]
+    public void OnValidityChanged_fires_true_after_all_valid_inputs_are_entered()
+    {
+        var (cut, lastValidity) = RenderStep();
+
+        // Simulate user filling in all four fields.
+        cut.Find("#username").Input("alice");
+        cut.Find("#password").Input("Secret1!");
+        cut.Find("#adminpassword").Input("Admin1!");
+        cut.Find("#bitlockerpin").Input("123456");
+
+        Assert.True(lastValidity(), "Step should be valid after all fields are correctly filled.");
+    }
+
+    [Fact]
+    public void OnValidityChanged_fires_false_when_a_field_is_cleared_after_being_valid()
+    {
+        var (cut, lastValidity) = RenderStep();
+
+        cut.Find("#username").Input("alice");
+        cut.Find("#password").Input("Secret1!");
+        cut.Find("#adminpassword").Input("Admin1!");
+        cut.Find("#bitlockerpin").Input("123456");
+
+        Assert.True(lastValidity()); // sanity
+
+        // Clear a required field — must revert to invalid.
+        cut.Find("#username").Input("");
+
+        Assert.False(lastValidity(), "Step should become invalid again when a required field is cleared.");
+    }
+
+    [Fact]
+    public void OnValidityChanged_fires_false_when_pin_is_non_numeric_or_too_short()
+    {
+        var (cut, lastValidity) = RenderStep();
+
+        cut.Find("#username").Input("alice");
+        cut.Find("#password").Input("Secret1!");
+        cut.Find("#adminpassword").Input("Admin1!");
+
+        // Too short — 5 digits.
+        cut.Find("#bitlockerpin").Input("12345");
+        Assert.False(lastValidity(), "PIN with only 5 digits must be invalid.");
+
+        // Non-numeric.
+        cut.Find("#bitlockerpin").Input("abc123");
+        Assert.False(lastValidity(), "Non-numeric PIN must be invalid.");
+
+        // Exactly 6 digits — valid.
+        cut.Find("#bitlockerpin").Input("123456");
+        Assert.True(lastValidity(), "Exactly 6 numeric digits is valid.");
+    }
+
+    [Fact]
+    public void OnValidityChanged_fires_true_on_mount_when_wizard_state_already_populated()
+    {
+        var prefilledState = new WizardState
+        {
+            Username = "alice",
+            Password = "Secret1!",
+            AdminPassword = "Admin1!",
+            BitLockerPin = "123456"
+        };
+
+        var (_, lastValidity) = RenderStep(prefilledState);
+
+        Assert.True(lastValidity(),
+            "Step should fire valid=true on mount when WizardState already has valid values (Back→Forward re-mount).");
+    }
+}