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.

src/ClaudeDo.Ui/ViewModels/Islands/TaskRowViewModel.cs

@@ -112,11 +112,31 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     [NotifyPropertyChangedFor(nameof(IsQueued))]
     [NotifyPropertyChangedFor(nameof(IsWaiting))]
     [NotifyPropertyChangedFor(nameof(StatusChipClass))]
+    [NotifyPropertyChangedFor(nameof(StatusLabel))]
+    [NotifyPropertyChangedFor(nameof(StatusChipTooltip))]
     [NotifyPropertyChangedFor(nameof(CanRemoveFromQueue))]
     private string? _blockedByTaskId;
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(DependsOnTaskId))]
     private IReadOnlyList<string> _dependsOnTaskIds = [];
+    // Extrinsic — assigned by TasksIslandViewModel.ApplyDependencyWaitState, which alone has the
+    // cross-row graph (plus any cross-list predecessor lookup) needed to tell an unmet
+    // task_dependencies edge from a satisfied one. True only for the task_dependencies case;
+    // IsWaiting also ORs in the older BlockedByTaskId planning-chain link.
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(IsQueued))]
+    [NotifyPropertyChangedFor(nameof(IsWaiting))]
+    [NotifyPropertyChangedFor(nameof(StatusChipClass))]
+    [NotifyPropertyChangedFor(nameof(StatusLabel))]
+    [NotifyPropertyChangedFor(nameof(StatusChipTooltip))]
+    [NotifyPropertyChangedFor(nameof(CanRemoveFromQueue))]
+    private bool _isBlockedByDependency;
+    // The predecessor(s) this row is waiting on, rendered ("#42" or "#42, #57"), or null when not
+    // waiting. Prefers BlockedByTaskId's single predecessor (the planning chain "parent wins" the
+    // same way it does for the chain rail), else lists every unmet task_dependencies edge.
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(StatusChipTooltip))]
+    private string? _dependencyWaitLabel;
 
     // The single predecessor, or null when the task has none or several. The chain rail can only
     // draw a line, so a task waiting on n predecessors gets a ChainAfterLabel instead — see
@@ -275,8 +295,8 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     // task). A live ConPTY session is that same shape but not parked — it reads "Interactive".
     public bool IsParked    => Status == TaskStatus.Idle && WorktreeState == ClaudeDo.Data.Models.WorktreeState.Active
                                && !HasInteractiveSession;
-    public bool IsQueued    => Status == TaskStatus.Queued && string.IsNullOrEmpty(BlockedByTaskId);
-    public bool IsWaiting   => Status == TaskStatus.Queued && !string.IsNullOrEmpty(BlockedByTaskId);
+    public bool IsQueued    => Status == TaskStatus.Queued && string.IsNullOrEmpty(BlockedByTaskId) && !IsBlockedByDependency;
+    public bool IsWaiting   => Status == TaskStatus.Queued && (!string.IsNullOrEmpty(BlockedByTaskId) || IsBlockedByDependency);
     public bool CanRemoveFromQueue => IsQueued || IsWaiting || HasQueuedSubtasks;
     // "Send to queue" is the single queue entry. On a finalized planning parent it queues the
     // plan (children) via CanQueuePlan; an Active (not-yet-finalized) planning parent is hidden —
@@ -412,9 +432,12 @@ public sealed partial class TaskRowViewModel : ViewModelBase
             : FailureReasonLabel;
 
     // Drives the status chip tooltip: an open interactive session takes priority (it's tappable),
-    // otherwise a Failed task's reason, otherwise no tooltip.
+    // then the predecessor(s) a waiting task is blocked on, then a Failed task's reason,
+    // otherwise no tooltip.
     public string? StatusChipTooltip
-        => HasInteractiveSession ? Loc.T("tasks.interactiveChipTip") : FailureReasonTooltip;
+        => HasInteractiveSession ? Loc.T("tasks.interactiveChipTip")
+         : IsWaiting && DependencyWaitLabel is not null ? Loc.T("tasks.waitingOnTip", DependencyWaitLabel)
+         : FailureReasonTooltip;
 
     public string DiffAdditionsText => $"+{DiffAdditions}";
     public string DiffDeletionsText => $"−{DiffDeletions}";
@@ -422,7 +445,8 @@ public sealed partial class TaskRowViewModel : ViewModelBase
 
     public string StatusLabel
         => HasInteractiveSession ? Loc.T("vm.taskStatus.interactive")
-         : IsParked ? Loc.T("vm.taskStatus.parked") : Status switch
+         : IsParked ? Loc.T("vm.taskStatus.parked")
+         : IsWaiting ? Loc.T("vm.taskStatus.waiting") : Status switch
     {
         TaskStatus.Idle             => Loc.T("vm.taskStatus.idle"),
         TaskStatus.Queued           => Loc.T("vm.taskStatus.queued"),
@@ -444,7 +468,7 @@ public sealed partial class TaskRowViewModel : ViewModelBase
 
     public string StatusChipClass => HasInteractiveSession
         ? "interactive"
-        : (Status, IsBlocked: !string.IsNullOrEmpty(BlockedByTaskId)) switch
+        : (Status, IsBlocked: !string.IsNullOrEmpty(BlockedByTaskId) || IsBlockedByDependency) switch
     {
         (TaskStatus.Running,            _) => "running",
         (TaskStatus.WaitingForReview,   _) => "review",

src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs

@@ -43,6 +43,12 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
     // Two events (TaskUpdated + WorktreeUpdated) drive the same delta refresh, so two reads for
     // one task can be in flight at once. Only the newest may write to the row.
     private readonly Dictionary<string, long> _deltaSeq = new();
+    // Number/Title/Status for a predecessor id that isn't loaded into Items (a different list, My
+    // Day, or the completed group) -- populated by RefreshExternalDependencyCacheAsync so
+    // ApplyChainGrouping/ApplyDependencyWaitState can still render "after #N" and the blocked
+    // chip for a cross-list predecessor instead of silently dropping it. Refreshed, never evicted:
+    // stale entries just get overwritten on the next load/delta that references the same id.
+    private readonly Dictionary<string, (int Number, string Title, TaskStatus Status)> _externalDependencyInfo = new();
     private long _deltaCounter;
     // Phase 3 reconcile tick — see the block at the end of this class.
     private readonly System.Timers.Timer _reconcileTimer = new(4_000);
@@ -363,6 +369,12 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
                     r.ParentTaskId == parent.Id && (r.IsQueued || r.IsWaiting));
         }
 
+        // entity is not null here whenever `existing` is still reachable (see the branching
+        // above: an early return covers every entity-null-but-existing case except delete, which
+        // needs no lookup refresh).
+        if (entity is not null && existing is not null)
+            await RefreshExternalDependencyCacheAsync(db, DependencyLookupIds([existing]));
+
         Regroup();
         UpdateSubtitle();
     }
@@ -548,6 +560,8 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
                 r.ParentFinalized = !string.IsNullOrEmpty(r.ParentTaskId)
                                     && finalizedParents.Contains(r.ParentTaskId!);
 
+            await RefreshExternalDependencyCacheAsync(db, DependencyLookupIds(Items), ct);
+
             Regroup();
             UpdateSubtitle();
             ok = true;
@@ -556,6 +570,32 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         finally { OperationTiming.Shared.Record("db", "TasksIsland.LoadForListAsync", sw.Elapsed, ok); }
     }
 
+    // Every predecessor id a row in `items` could need labelled/checked: its task_dependencies
+    // edges plus the planning chain's BlockedByTaskId (both resolved the same way in
+    // ApplyDependencyWaitState/BuildAfterLabel).
+    private static IEnumerable<string> DependencyLookupIds(IEnumerable<TaskRowViewModel> items) =>
+        items.SelectMany(r => string.IsNullOrEmpty(r.BlockedByTaskId)
+            ? r.DependsOnTaskIds
+            : r.DependsOnTaskIds.Append(r.BlockedByTaskId));
+
+    // Resolves predecessor ids that aren't loaded into Items (a different list, My Day, or the
+    // completed group) so cross-list dependency display doesn't silently drop them. Cheap: reuses
+    // the caller's already-open context, one query for however many ids are actually missing.
+    private async Task RefreshExternalDependencyCacheAsync(
+        ClaudeDoDbContext db, IEnumerable<string> ids, CancellationToken ct = default)
+    {
+        var known = Items.Select(r => r.Id).ToHashSet();
+        var missing = ids.Where(id => !string.IsNullOrEmpty(id) && !known.Contains(id)).Distinct().ToList();
+        if (missing.Count == 0) return;
+
+        var rows = await db.Tasks
+            .Where(t => missing.Contains(t.Id))
+            .Select(t => new { t.Id, t.Number, t.Title, t.Status })
+            .ToListAsync(ct);
+        foreach (var r in rows)
+            _externalDependencyInfo[r.Id] = (r.Number, r.Title, r.Status);
+    }
+
     internal void Regroup()
     {
         // Collapse parents that have children by default, so subtasks stay tucked away until
@@ -691,13 +731,66 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         // with a label rather than an orphaned rail. Whether the head is resolvable at all
         // still uses the whole-Items graph (rowsById), independent of section.
         var rowsById = Items.ToDictionary(r => r.Id);
-        overdue   = ApplyChainGrouping(overdue, rowsById);
-        open      = ApplyChainGrouping(open, rowsById);
-        completed = ApplyChainGrouping(completed, rowsById);
+
+        // Blocked-by-dependency is independent of section (a blocked row can be Overdue or Open
+        // alike) and independent of chain membership, so it's computed once over all of Items
+        // rather than per section.
+        foreach (var r in Items)
+            ApplyDependencyWaitState(r, rowsById, _externalDependencyInfo);
+
+        overdue   = ApplyChainGrouping(overdue, rowsById, _externalDependencyInfo);
+        open      = ApplyChainGrouping(open, rowsById, _externalDependencyInfo);
+        completed = ApplyChainGrouping(completed, rowsById, _externalDependencyInfo);
 
         return (overdue, open, completed);
     }
 
+    // Assigns IsBlockedByDependency/DependencyWaitLabel for one row. BlockedByTaskId (the planning
+    // chain's single link) wins the label the same way a planning child's parent indent wins over
+    // chain-rail membership -- "parent wins" is the existing precedent (ApplyChainGrouping below).
+    private static void ApplyDependencyWaitState(
+        TaskRowViewModel row, Dictionary<string, TaskRowViewModel> rowsById,
+        IReadOnlyDictionary<string, (int Number, string Title, TaskStatus Status)> external)
+    {
+        if (row.Status != TaskStatus.Queued)
+        {
+            row.IsBlockedByDependency = false;
+            row.DependencyWaitLabel = null;
+            return;
+        }
+
+        var unmet = row.DependsOnTaskIds.Where(id => IsUnmet(id, rowsById, external)).ToList();
+        row.IsBlockedByDependency = unmet.Count > 0;
+
+        var waitIds = !string.IsNullOrEmpty(row.BlockedByTaskId) ? [row.BlockedByTaskId] : unmet;
+        row.DependencyWaitLabel = waitIds.Count == 0 ? null
+            : string.Join(", ", waitIds.Select(id => ResolveLabel(id, rowsById, external)).Where(s => s is not null));
+    }
+
+    // A predecessor missing from both rowsById and the external cache counts as unmet -- mirrors
+    // QueuePicker/Worker's TaskBlocking.Unmet: an edge pointing at an unresolved/vanished task
+    // keeps blocking rather than being silently treated as satisfied.
+    private static bool IsUnmet(
+        string id, Dictionary<string, TaskRowViewModel> rowsById,
+        IReadOnlyDictionary<string, (int Number, string Title, TaskStatus Status)> external)
+    {
+        if (rowsById.TryGetValue(id, out var p)) return p.Status != TaskStatus.Done;
+        if (external.TryGetValue(id, out var e)) return e.Status != TaskStatus.Done;
+        return true;
+    }
+
+    // Resolves a predecessor id to its display label, checking the in-view rows first and falling
+    // back to the cross-list cache (RefreshExternalDependencyCacheAsync) -- null only when the
+    // predecessor is genuinely unresolvable anywhere (e.g. a deleted task).
+    private static string? ResolveLabel(
+        string id, Dictionary<string, TaskRowViewModel> rowsById,
+        IReadOnlyDictionary<string, (int Number, string Title, TaskStatus Status)> external)
+    {
+        if (rowsById.TryGetValue(id, out var p)) return p.Number > 0 ? $"#{p.Number}" : p.Title;
+        if (external.TryGetValue(id, out var e)) return e.Number > 0 ? $"#{e.Number}" : e.Title;
+        return null;
+    }
+
     // Cycles are rejected by TaskStateService.SetDependsOnAsync, so this should always
     // terminate quickly — capped anyway against a corrupt/legacy row forming a loop.
     private const int MaxChainWalkDepth = 64;
@@ -724,14 +817,15 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
 
     // Content only — "after " + localization is Slice 2's concern (the view), which is why this
     // holds just the identifying fragment rather than an assembled sentence. Names every
-    // predecessor it can resolve: a task can wait on n of them, and hiding all but the first
-    // would misreport what the row is actually waiting for.
-    private static string? BuildAfterLabel(TaskRowViewModel row, Dictionary<string, TaskRowViewModel> rowsById)
+    // predecessor it can resolve (in-view first, then the cross-list external cache): a task can
+    // wait on n of them, and hiding all but the first would misreport what the row is waiting for.
+    private static string? BuildAfterLabel(
+        TaskRowViewModel row, Dictionary<string, TaskRowViewModel> rowsById,
+        IReadOnlyDictionary<string, (int Number, string Title, TaskStatus Status)> external)
     {
         var parts = row.DependsOnTaskIds
-            .Select(id => rowsById.TryGetValue(id, out var p) ? p : null)
+            .Select(id => ResolveLabel(id, rowsById, external))
             .Where(p => p is not null)
-            .Select(p => p!.Number > 0 ? $"#{p.Number}" : p.Title)
             .ToList();
         return parts.Count == 0 ? null : string.Join(", ", parts);
     }
@@ -741,7 +835,8 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
     // (ascending ChainStep), regardless of their SortOrder-derived position — mirroring how
     // planning children already sit right after their parent regardless of Items order.
     private static List<TaskRowViewModel> ApplyChainGrouping(
-        List<TaskRowViewModel> section, Dictionary<string, TaskRowViewModel> rowsById)
+        List<TaskRowViewModel> section, Dictionary<string, TaskRowViewModel> rowsById,
+        IReadOnlyDictionary<string, (int Number, string Title, TaskStatus Status)> external)
     {
         var sectionIds = section.Select(r => r.Id).ToHashSet();
         var headIdOf = new Dictionary<TaskRowViewModel, string>();
@@ -763,7 +858,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
             {
                 r.ShowAsChainMember = false;
                 r.ChainStep = null;
-                r.ChainAfterLabel = BuildAfterLabel(r, rowsById);
+                r.ChainAfterLabel = BuildAfterLabel(r, rowsById, external);
                 continue;
             }
 
@@ -773,7 +868,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
             {
                 r.ShowAsChainMember = false;
                 r.ChainStep = null;
-                r.ChainAfterLabel = BuildAfterLabel(r, rowsById);
+                r.ChainAfterLabel = BuildAfterLabel(r, rowsById, external);
                 continue;
             }
 
@@ -790,7 +885,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
             {
                 r.ShowAsChainMember = false;
                 r.ChainStep = null;
-                r.ChainAfterLabel = BuildAfterLabel(r, rowsById);
+                r.ChainAfterLabel = BuildAfterLabel(r, rowsById, external);
             }
         }
 
@@ -1739,7 +1834,12 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         // reflects any of that after a Regroup — without this the tick would heal the row's data
         // while leaving a completed task sitting in the Open section under a stale count. Gated
         // on a real change so an idle tick stays free.
-        if (groupingChanged) Regroup();
+        if (groupingChanged)
+        {
+            await using var db2 = await _dbFactory.CreateDbContextAsync(ct);
+            await RefreshExternalDependencyCacheAsync(db2, DependencyLookupIds(Items), ct);
+            Regroup();
+        }
     }
 
     // The slice of a row that Regroup reads: which section it lands in, where it sits inside it,