feat(ui): surface depends_on blocking in status chip, chain label, and detail pane

Usability-Audit 2026-09-10 found three gaps versus the dependency-chain-display
spec: a Queued task blocked on an unmet task_dependencies edge rendered the same
chip as one about to run, a cross-list predecessor silently dropped the
"after #N" chip, and the detail pane showed nothing about a wait at all.

- TaskRowViewModel gains IsBlockedByDependency/DependencyWaitLabel (extrinsic,
  assigned by TasksIslandViewModel like the existing chain fields); IsQueued/
  IsWaiting/StatusChipClass/StatusLabel/StatusChipTooltip now account for it
  alongside the existing BlockedByTaskId planning-chain link.
- TasksIslandViewModel.ApplyDependencyWaitState computes the blocked flag and
  wait label per row; a new RefreshExternalDependencyCacheAsync backfills
  Number/Title/Status for predecessors not loaded into the current list's
  Items (reusing the already-open DbContext, no new hub method), so
  BuildAfterLabel/blocking both resolve a listenfremder Vorgänger correctly.
- New "waiting" chip style (IslandStyles.axaml) and locale keys (en+de);
  TaskHeaderBar shows a "Waiting on #N" line bound straight to the same row.

Tests: TasksIslandChainTests (blocked/unblocked chip, cross-list predecessor),
DetailsIslandDependencyWaitTests (new), TaskRowViewModelNotificationsTests
updated for the new notification set.

tests/ClaudeDo.Ui.Tests/ViewModels/DetailsIslandDependencyWaitTests.cs

@@ -0,0 +1,72 @@
+using ClaudeDo.Data;
+using ClaudeDo.Ui.Services;
+using ClaudeDo.Ui.ViewModels.Islands;
+using Microsoft.EntityFrameworkCore;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Ui.Tests.ViewModels;
+
+// Usability-Audit 2026-09-10: the detail pane showed nothing when a task was blocked on a
+// predecessor -- the header bar now renders a "Waiting on #N" line bound straight to the same
+// Task.IsWaiting/DependencyWaitLabel TasksIslandViewModel already computes (no new VM logic here).
+public class DetailsIslandDependencyWaitTests : IDisposable
+{
+    private readonly string _dbPath;
+
+    public DetailsIslandDependencyWaitTests()
+    {
+        _dbPath = Path.Combine(Path.GetTempPath(), $"claudedo_dep_wait_test_{Guid.NewGuid():N}.db");
+        using var ctx = NewContext();
+        ctx.Database.EnsureCreated();
+    }
+
+    public void Dispose()
+    {
+        try { File.Delete(_dbPath); } catch { }
+        try { File.Delete(_dbPath + "-wal"); } catch { }
+        try { File.Delete(_dbPath + "-shm"); } catch { }
+    }
+
+    private ClaudeDoDbContext NewContext()
+    {
+        var opts = new DbContextOptionsBuilder<ClaudeDoDbContext>()
+            .UseSqlite($"Data Source={_dbPath}")
+            .Options;
+        return new ClaudeDoDbContext(opts);
+    }
+
+    private DetailsIslandViewModel NewVm()
+    {
+        var factory = new TestDbFactory(NewContext);
+        return new DetailsIslandViewModel(factory, new DefaultStub(), new NullServiceProvider(), new ClaudeDo.Ui.Services.MergeCoordinator());
+    }
+
+    [Fact]
+    public void UnblockedTask_HasNoWaitingLine()
+    {
+        var vm = NewVm();
+        vm.Bind(new TaskRowViewModel { Id = Guid.NewGuid().ToString("N"), Number = 1, Status = TaskStatus.Queued });
+
+        Assert.False(vm.Task!.IsWaiting);
+        Assert.Null(vm.Task.DependencyWaitLabel);
+    }
+
+    [Fact]
+    public void BlockedTask_ExposesWaitingLineViaBoundRow()
+    {
+        var vm = NewVm();
+        var row = new TaskRowViewModel
+        {
+            Id = Guid.NewGuid().ToString("N"),
+            Number = 2,
+            Status = TaskStatus.Queued,
+            IsBlockedByDependency = true,
+            DependencyWaitLabel = "#42",
+        };
+
+        vm.Bind(row);
+
+        Assert.True(vm.Task!.IsWaiting);
+        Assert.Equal("#42", vm.Task.DependencyWaitLabel);
+    }
+}

tests/ClaudeDo.Ui.Tests/ViewModels/TasksIslandChainTests.cs

@@ -266,4 +266,93 @@ public class TasksIslandChainTests : IDisposable
         Assert.Contains(numbers["a"].ToString(), wiring.ChainAfterLabel);
         Assert.Contains(numbers["b"].ToString(), wiring.ChainAfterLabel);
     }
+
+    // Usability-Audit 2026-09-10: a Queued task blocked on an unmet task_dependencies edge used to
+    // render the same "queued" chip as one that's actually next up to run.
+    [Fact]
+    public async Task QueuedTaskWithUnmetDependency_ShowsWaitingChipAndTooltip()
+    {
+        var numbers = await SeedAsync(
+            ("predecessor", TaskStatus.Idle, null, null, 0),
+            ("dependent", TaskStatus.Queued, "predecessor", null, 1));
+
+        var vm = BuildViewModel();
+        await LoadAndWaitAsync(vm, UserList("list1", "Default"));
+
+        var dependent = vm.Items.First(r => r.Id == "dependent");
+
+        Assert.True(dependent.IsWaiting);
+        Assert.False(dependent.IsQueued);
+        Assert.Equal("waiting", dependent.StatusChipClass);
+        Assert.NotNull(dependent.StatusChipTooltip);
+        Assert.Contains(numbers["predecessor"].ToString(), dependent.StatusChipTooltip);
+    }
+
+    [Fact]
+    public async Task QueuedTaskWithSatisfiedDependency_ShowsPlainQueuedChip()
+    {
+        await SeedAsync(
+            ("predecessor", TaskStatus.Done, null, null, 0),
+            ("dependent", TaskStatus.Queued, "predecessor", null, 1));
+
+        var vm = BuildViewModel();
+        await LoadAndWaitAsync(vm, UserList("list1", "Default"));
+
+        var dependent = vm.Items.First(r => r.Id == "dependent");
+
+        Assert.False(dependent.IsWaiting);
+        Assert.True(dependent.IsQueued);
+        Assert.Equal("queued", dependent.StatusChipClass);
+        Assert.Null(dependent.DependencyWaitLabel);
+    }
+
+    // Usability-Audit 2026-09-10: BuildAfterLabel only resolved predecessors already loaded into
+    // Items, so a listenfremder Vorgänger (different list) silently dropped both the "after #N"
+    // chip and the blocked chip. RefreshExternalDependencyCacheAsync backfills Number/Title/Status
+    // for exactly those ids via one extra query on the already-open DbContext.
+    [Fact]
+    public async Task CrossListPredecessor_BlocksAndRendersAfterLabel()
+    {
+        var headNumber = TestTaskNumbers.Next();
+        await using (var db = NewContext())
+        {
+            db.Lists.Add(new ListEntity { Id = "list1", Name = "Default", CreatedAt = DateTime.UtcNow });
+            db.Lists.Add(new ListEntity { Id = "list2", Name = "Other", CreatedAt = DateTime.UtcNow });
+            db.Tasks.Add(new TaskEntity
+            {
+                Number = headNumber,
+                Id = "head",
+                ListId = "list1",
+                Title = "head",
+                CreatedAt = DateTime.UtcNow,
+                Status = TaskStatus.Idle,
+                SortOrder = 0,
+            });
+            db.Tasks.Add(new TaskEntity
+            {
+                Number = TestTaskNumbers.Next(),
+                Id = "dependent",
+                ListId = "list2",
+                Title = "dependent",
+                CreatedAt = DateTime.UtcNow,
+                Status = TaskStatus.Queued,
+                SortOrder = 0,
+            });
+            db.TaskDependencies.Add(new TaskDependencyEntity { TaskId = "dependent", DependsOnTaskId = "head" });
+            await db.SaveChangesAsync();
+        }
+
+        var vm = BuildViewModel();
+        await LoadAndWaitAsync(vm, UserList("list2", "Other"));
+
+        var dependent = vm.Items.First(r => r.Id == "dependent");
+
+        Assert.True(dependent.IsWaiting);
+        Assert.False(dependent.IsQueued);
+        Assert.Equal("waiting", dependent.StatusChipClass);
+        Assert.NotNull(dependent.ChainAfterLabel);
+        Assert.Contains($"#{headNumber}", dependent.ChainAfterLabel);
+        Assert.NotNull(dependent.DependencyWaitLabel);
+        Assert.Contains($"#{headNumber}", dependent.DependencyWaitLabel);
+    }
 }