refactor(claude-do): merge TaskRowViewModel: CanX und DisabledReason aus einer Gate-Met

ClaudeDo-Task: 6c4b27aa-1b5e-4d73-98f5-dcafa3935247

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

@@ -159,4 +159,76 @@ public class TaskRowContextMenuTests
         row.IsSelected = isSelected;
         Assert.Equal(expected, row.ShowRowActions);
     }
+
+    // Pins down what the gate methods guarantee by construction: each of the five CanX/reason
+    // pairs must agree on every reachable state, not just the handful of examples above. Swept
+    // across the full state matrix (every TaskStatus x PlanningPhase x IsChild/ParentFinalized x
+    // IsManual x HasInteractiveSession x HasQueuedSubtasks x IsRefining) rather than one example
+    // per gate, so a future edit to a gate's condition without touching its Reason branch (or
+    // vice versa) fails loudly instead of silently drifting.
+    public static IEnumerable<object[]> GateStateMatrix()
+    {
+        foreach (var status in Enum.GetValues<TaskStatus>())
+        foreach (var phase in Enum.GetValues<PlanningPhase>())
+        foreach (var isChild in Bools)
+        foreach (var parentFinalized in Bools)
+        foreach (var isManual in Bools)
+        foreach (var hasInteractiveSession in Bools)
+        foreach (var hasQueuedSubtasks in Bools)
+        foreach (var isRefining in Bools)
+            yield return new object[]
+            {
+                status, phase, isChild, parentFinalized, isManual,
+                hasInteractiveSession, hasQueuedSubtasks, isRefining,
+            };
+    }
+
+    private static readonly bool[] Bools = { false, true };
+
+    [Theory]
+    [MemberData(nameof(GateStateMatrix))]
+    public void CanX_Agrees_With_DisabledReason_Across_State_Matrix(
+        TaskStatus status, PlanningPhase phase, bool isChild, bool parentFinalized, bool isManual,
+        bool hasInteractiveSession, bool hasQueuedSubtasks, bool isRefining)
+    {
+        var row = new TaskRowViewModel
+        {
+            Id = "t1",
+            Status = status,
+            PlanningPhase = phase,
+            ParentTaskId = isChild ? "parent-id" : null,
+            ParentFinalized = parentFinalized,
+            IsManual = isManual,
+            HasInteractiveSession = hasInteractiveSession,
+            HasQueuedSubtasks = hasQueuedSubtasks,
+            IsRefining = isRefining,
+        };
+
+        Assert.Equal(row.CanSendToQueue, row.SendToQueueDisabledReason is null);
+        Assert.Equal(row.IsRunning, row.CancelDisabledReason is null);
+        Assert.Equal(row.CanRefine, row.RefineDisabledReason is null);
+
+        var canOpenPlanningMenu = row.CanOpenPlanningSession || row.CanResumeOrDiscardPlanning || row.CanFinalizePlanning;
+        Assert.Equal(canOpenPlanningMenu, row.PlanningDisabledReason is null);
+    }
+
+    [Fact]
+    public void OpenWorktreeDisabledReason_Agrees_With_CanOpenWorktree_When_NoPath()
+    {
+        var row = MakeRow();
+        Assert.Equal(row.CanOpenWorktree, row.OpenWorktreeDisabledReason is null);
+    }
+
+    [Fact]
+    public void OpenWorktreeDisabledReason_Agrees_With_CanOpenWorktree_When_Path_Exists()
+    {
+        var dir = Directory.CreateTempSubdirectory();
+        try
+        {
+            var row = MakeRow();
+            row.WorktreePath = dir.FullName;
+            Assert.Equal(row.CanOpenWorktree, row.OpenWorktreeDisabledReason is null);
+        }
+        finally { dir.Delete(true); }
+    }
 }