fix(worker): reorder PlanningAggregator checkout/delete and kill git on cancel

Also stub new IWorkerClient planning members in FakeWorkerClient to restore build.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Worker/Planning/PlanningAggregator.cs

@@ -78,11 +78,13 @@ public sealed class PlanningAggregator
 
         var integrationBranch = BuildIntegrationBranchName(planning);
 
-        // Reset: delete if exists, then recreate off the target branch.
+        // Reset: checkout target first (so we're never ON the integration branch when deleting it),
+        // then delete if exists, then recreate off the target branch.
+        await _git.CheckoutBranchAsync(repoDir, targetBranch, ct);
+
         try { await _git.BranchDeleteAsync(repoDir, integrationBranch, force: true, ct); }
         catch { /* didn't exist */ }
 
-        await _git.CheckoutBranchAsync(repoDir, targetBranch, ct);
         await GitRawAsync(repoDir, ct, "checkout", "-b", integrationBranch);
 
         foreach (var child in childSubtasks)
@@ -150,7 +152,15 @@ public sealed class PlanningAggregator
         using var p = System.Diagnostics.Process.Start(psi)!;
         var stdoutTask = p.StandardOutput.ReadToEndAsync();
         var stderrTask = p.StandardError.ReadToEndAsync();
-        await p.WaitForExitAsync(ct);
+        try
+        {
+            await p.WaitForExitAsync(ct);
+        }
+        catch (OperationCanceledException)
+        {
+            try { if (!p.HasExited) p.Kill(entireProcessTree: true); } catch { }
+            throw;
+        }
         var stdout = await stdoutTask;
         var stderr = await stderrTask;
         if (p.ExitCode != 0) throw new InvalidOperationException($"git {string.Join(' ', args)} failed: {stderr}");

tests/ClaudeDo.Worker.Tests/UiVm/TasksIslandViewModelPlanningTests.cs

@@ -32,6 +32,19 @@ sealed class FakeWorkerClient : IWorkerClient
     public Task DiscardPlanningSessionAsync(string taskId, CancellationToken ct = default) { DiscardPlanningCalls++; return Task.CompletedTask; }
     public Task FinalizePlanningSessionAsync(string taskId, bool queueAgentTasks = true, CancellationToken ct = default) { FinalizePlanningCalls++; return Task.CompletedTask; }
     public Task<int> GetPendingDraftCountAsync(string taskId, CancellationToken ct = default) => Task.FromResult(0);
+
+    public event Action<string, string>? PlanningMergeStartedEvent;
+    public event Action<string, string>? PlanningSubtaskMergedEvent;
+    public event Action<string, string, IReadOnlyList<string>>? PlanningMergeConflictEvent;
+    public event Action<string>? PlanningMergeAbortedEvent;
+    public event Action<string>? PlanningCompletedEvent;
+
+    public Task<MergeTargetsDto?> GetMergeTargetsAsync(string taskId) => Task.FromResult<MergeTargetsDto?>(null);
+    public Task<IReadOnlyList<SubtaskDiffDto>> GetPlanningAggregateAsync(string planningTaskId) => Task.FromResult<IReadOnlyList<SubtaskDiffDto>>(Array.Empty<SubtaskDiffDto>());
+    public Task<CombinedDiffResultDto?> BuildPlanningIntegrationBranchAsync(string planningTaskId, string targetBranch) => Task.FromResult<CombinedDiffResultDto?>(null);
+    public Task MergeAllPlanningAsync(string planningTaskId, string targetBranch) => Task.CompletedTask;
+    public Task ContinuePlanningMergeAsync(string planningTaskId) => Task.CompletedTask;
+    public Task AbortPlanningMergeAsync(string planningTaskId) => Task.CompletedTask;
 }
 
 // ── Helper to build VM with pre-seeded Items ──────────────────────────────────