MergeNotice in the layout and a Merge status link on Membership status

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/Bifrost.Web/Pages/Membership/Status.cshtml

@@ -32,6 +32,14 @@
         </div>
     }
 
+    @if (Model.HasMerges)
+    {
+        <div class="panel-actions">
+            <a class="button secondary" asp-page="/Membership/MergeStatus">Merge status</a>
+            <span class="muted">See an account merge and, for seven days, undo it.</span>
+        </div>
+    }
+
     @if (Model.Invitation is not null)
     {
         <div class="callout success">

src/Bifrost.Web/Pages/Membership/Status.cshtml.cs

@@ -17,6 +17,9 @@ public sealed class StatusModel(
     /// <summary>Whether this session belongs to a Heimdall account whose logins the Linked accounts page can manage.</summary>
     public bool CanManageLogins => User.FindFirstValue(BifrostClaimTypes.HeimdallAccountId) is { Length: > 0 };
 
+    /// <summary>Whether this account is in, or was in, a merge: the link to Merge status is shown only then.</summary>
+    public bool HasMerges { get; private set; }
+
     public CurrentBifrostActor Actor { get; private set; } = CurrentBifrostActor.Anonymous;
 
     public MembershipInvitation? Invitation { get; private set; }
@@ -50,6 +53,9 @@ public sealed class StatusModel(
     public async Task OnGetAsync(CancellationToken cancellationToken)
     {
         Actor = await actorAccessor.GetAsync(cancellationToken);
+        HasMerges = Actor.Merge is not null
+            || (Actor.UserAccount is { } account
+                && await dbContext.AccountMerges.AnyAsync(x => x.SurvivorUserAccountId == account.Id || x.FoldedUserAccountId == account.Id, cancellationToken));
 
         if (Actor.UserAccount is null)
         {

src/Bifrost.Web/Pages/Shared/Components/MergeNotice/Default.cshtml

@@ -0,0 +1,5 @@
+@model string
+<aside class="merge-notice" role="status">
+    <span>@Model</span>
+    <a asp-page="/Membership/MergeStatus">Merge status</a>
+</aside>

src/Bifrost.Web/Pages/Shared/_Layout.cshtml

@@ -57,6 +57,11 @@
             </div>
         </header>
 
+        @if (User.Identity?.IsAuthenticated == true)
+        {
+            @await Component.InvokeAsync("MergeNotice")
+        }
+
         <main class="page-frame">
             @RenderBody()
         </main>

src/Bifrost.Web/ViewComponents/MergeNotice.cs

@@ -1,9 +1,55 @@
+using Bifrost.Web.Data;
+using Bifrost.Web.Domain;
+using Bifrost.Web.Features.Membership;
+using Bifrost.Web.Features.Shared;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 
 namespace Bifrost.Web.ViewComponents;
 
-/// <summary>Skeleton: the layout's merge notice. Filled in by the cut's next commits.</summary>
-public sealed class MergeNotice : ViewComponent
+/// <summary>
+/// The layout's merge notice for a signed-in actor: the survivor of a Committed or UndoRequested merge inside its grace (days left), a
+/// frozen account (a merge is in progress) or a folded one (where to sign in). It reads the merge row once per page view and keeps no
+/// state of its own; the words are <see cref="MergeWording"/>'s, and no account name or id is ever in them.
+/// </summary>
+public sealed class MergeNotice(ICurrentBifrostActorAccessor actors, BifrostDbContext dbContext, TimeProvider timeProvider) : ViewComponent
 {
-    public IViewComponentResult Invoke() => Content(string.Empty);
+    public async Task<IViewComponentResult> InvokeAsync()
+    {
+        var actor = await actors.GetAsync(HttpContext.RequestAborted);
+        var text = await TextAsync(actor, HttpContext.RequestAborted);
+        return text is null ? Content(string.Empty) : View("Default", text);
+    }
+
+    private async Task<string?> TextAsync(CurrentBifrostActor actor, CancellationToken cancellationToken)
+    {
+        var now = timeProvider.GetUtcNow();
+        if (actor.Merge is { } standing)
+        {
+            if (standing is MergeStanding.Frozen)
+            {
+                return MergeWording.FrozenNotice();
+            }
+
+            var mergedOn = await dbContext.AccountMerges.AsNoTracking()
+                .Where(x => x.Id == standing.MergeId)
+                .Select(x => x.CommittedUtc ?? x.CreatedUtc)
+                .FirstOrDefaultAsync(cancellationToken);
+            return MergeWording.FoldedNotice(mergedOn);
+        }
+
+        if (actor.UserAccount is not { } account)
+        {
+            return null;
+        }
+
+        var graceEnds = await dbContext.AccountMerges.AsNoTracking()
+            .Where(x => x.SurvivorUserAccountId == account.Id
+                && (x.State == AccountMergeState.Committed || x.State == AccountMergeState.UndoRequested)
+                && x.GraceEndsUtc > now)
+            .OrderBy(x => x.GraceEndsUtc)
+            .Select(x => x.GraceEndsUtc)
+            .FirstOrDefaultAsync(cancellationToken);
+        return graceEnds is { } end ? MergeWording.SurvivorNotice(MergeWording.DaysUntil(end, now)) : null;
+    }
 }

tests/Bifrost.Web.Tests/MergeStatusTests.cs

@@ -16,7 +16,7 @@ namespace Bifrost.Web.Tests;
 /// </summary>
 public sealed class MergeStatusTests
 {
-    private static string Enc(string text) => WebUtility.HtmlEncode(text);
+    private static string Enc(string text) => System.Text.Encodings.Web.HtmlEncoder.Default.Encode(text);
 
     private static int Notices(string html) => Regex.Matches(html, "class=\"merge-notice\"").Count;
 
@@ -113,6 +113,8 @@ public sealed class MergeStatusTests
         var final = await Html(w, w.SurvivorSession);
         Assert.Equal(AccountMergeState.Final, (await rig.MergeAsync(w.MergeId)).State);
         Assert.Equal(0, Notices(final));
+        Assert.Contains("/Membership/MergeStatus", await Html(w, w.SurvivorSession, "/Membership/Status"));
+        Assert.DoesNotContain("/Membership/MergeStatus", await Html(w, w.StrangerSession, "/Membership/Status"));
         Assert.Contains(Enc(MergeWording.State(AccountMergeState.Final)), final);
 
         foreach (var state in new[] { AccountMergeState.Undone, AccountMergeState.Failed })