feat(worker): planning finalize enters WaitingForChildren

A finalized planning parent now joins the unified parent lifecycle:
WaitingForChildren while its child chain runs (or WaitingForReview directly
if it has no children), advancing to review like an improvement parent.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/ClaudeDo.Worker.Tests/WaitingForChildrenLifecycleTests.cs

@@ -2,6 +2,7 @@ using ClaudeDo.Data;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Worker.Tests.Infrastructure;
+using Microsoft.EntityFrameworkCore;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 using Xunit;
 
@@ -160,4 +161,95 @@ public sealed class WaitingForChildrenLifecycleTests : IDisposable
             Assert.Equal(TaskStatus.WaitingForReview, par!.Status);
         }
     }
+
+    // ─── FinalizePlanningAsync ────────────────────────────────────────────
+
+    private async Task<string> SeedActivePlanningParentAsync(string id = "par")
+    {
+        using var ctx = _db.CreateContext();
+        if (!ctx.Lists.Any())
+            ctx.Lists.Add(new ListEntity { Id = "l1", Name = "L", CreatedAt = DateTime.UtcNow });
+        ctx.Tasks.Add(new TaskEntity
+        {
+            Id = id,
+            ListId = "l1",
+            Title = "Parent",
+            Status = TaskStatus.Idle,
+            PlanningPhase = PlanningPhase.Active,
+            CreatedAt = DateTime.UtcNow,
+        });
+        await ctx.SaveChangesAsync();
+        return id;
+    }
+
+    private async Task SeedChildAsync(string parentId, string childId, TaskStatus status = TaskStatus.Idle)
+    {
+        using var ctx = _db.CreateContext();
+        ctx.Tasks.Add(new TaskEntity
+        {
+            Id = childId,
+            ListId = "l1",
+            Title = "Child",
+            Status = status,
+            ParentTaskId = parentId,
+            CreatedAt = DateTime.UtcNow,
+        });
+        await ctx.SaveChangesAsync();
+    }
+
+    [Fact]
+    public async Task FinalizePlanning_WithChildren_SetsWaitingForChildren_AndPlanningFinalized()
+    {
+        await SeedActivePlanningParentAsync();
+        await SeedChildAsync("par", "c1");
+        await SeedChildAsync("par", "c2");
+
+        var result = await _built.State.FinalizePlanningAsync("par", default);
+
+        Assert.True(result.Ok);
+        using var ctx = _db.CreateContext();
+        var parent = await new TaskRepository(ctx).GetByIdAsync("par");
+        Assert.Equal(TaskStatus.WaitingForChildren, parent!.Status);
+        Assert.Equal(PlanningPhase.Finalized, parent.PlanningPhase);
+    }
+
+    [Fact]
+    public async Task FinalizePlanning_WithChildren_ThenAllChildrenTerminal_AdvancesToWaitingForReview()
+    {
+        await SeedActivePlanningParentAsync();
+        await SeedChildAsync("par", "c1");
+        await SeedChildAsync("par", "c2");
+
+        await _built.State.FinalizePlanningAsync("par", default);
+
+        // Manually transition parent to WaitingForChildren so CompleteAsync works on the children.
+        // Children are Idle — complete them by seeding them as Running first.
+        using (var ctx = _db.CreateContext())
+        {
+            await ctx.Tasks.Where(t => t.Id == "c1").ExecuteUpdateAsync(s => s.SetProperty(t => t.Status, TaskStatus.Running));
+            await ctx.Tasks.Where(t => t.Id == "c2").ExecuteUpdateAsync(s => s.SetProperty(t => t.Status, TaskStatus.Running));
+        }
+
+        await _built.State.CompleteAsync("c1", DateTime.UtcNow, "ok", default);
+        using (var ctx = _db.CreateContext())
+            Assert.Equal(TaskStatus.WaitingForChildren, (await new TaskRepository(ctx).GetByIdAsync("par"))!.Status);
+
+        await _built.State.CompleteAsync("c2", DateTime.UtcNow, "ok", default);
+        using (var ctx = _db.CreateContext())
+            Assert.Equal(TaskStatus.WaitingForReview, (await new TaskRepository(ctx).GetByIdAsync("par"))!.Status);
+    }
+
+    [Fact]
+    public async Task FinalizePlanning_WithNoChildren_SetsWaitingForReview_Directly()
+    {
+        await SeedActivePlanningParentAsync();
+
+        var result = await _built.State.FinalizePlanningAsync("par", default);
+
+        Assert.True(result.Ok);
+        using var ctx = _db.CreateContext();
+        var parent = await new TaskRepository(ctx).GetByIdAsync("par");
+        Assert.Equal(TaskStatus.WaitingForReview, parent!.Status);
+        Assert.Equal(PlanningPhase.Finalized, parent.PlanningPhase);
+    }
 }