feat(worker): PlanningSessionManager.DiscardAsync

tests/ClaudeDo.Worker.Tests/Planning/PlanningSessionManagerTests.cs

@@ -159,4 +159,20 @@ public sealed class PlanningSessionManagerTests : IDisposable
         await Assert.ThrowsAsync<InvalidOperationException>(() =>
             _sut.ResumeAsync(parent.Id, CancellationToken.None));
     }
+
+    [Fact]
+    public async Task DiscardAsync_DeletesSessionDirAndResetsTask()
+    {
+        var (listId, _) = await SeedListAsync();
+        var parent = await SeedManualTaskAsync(listId);
+        var startCtx = await _sut.StartAsync(parent.Id, CancellationToken.None);
+        Assert.True(Directory.Exists(startCtx.Files.SessionDirectory));
+
+        await _sut.DiscardAsync(parent.Id, CancellationToken.None);
+
+        Assert.False(Directory.Exists(startCtx.Files.SessionDirectory));
+        var loaded = await _tasks.GetByIdAsync(parent.Id);
+        Assert.Equal(TaskStatus.Manual, loaded!.Status);
+        Assert.Null(loaded.PlanningSessionToken);
+    }
 }