diff --git a/src/ClaudeDo.Worker/Planning/PlanningSessionManager.cs b/src/ClaudeDo.Worker/Planning/PlanningSessionManager.cs
index 67194ab..c312873 100644
--- a/src/ClaudeDo.Worker/Planning/PlanningSessionManager.cs
+++ b/src/ClaudeDo.Worker/Planning/PlanningSessionManager.cs
@@ -53,6 +53,19 @@ public sealed class PlanningSessionManager
         return new PlanningSessionStartContext(taskId, list.WorkingDir, files);
     }
 
+    public async Task DiscardAsync(string taskId, CancellationToken ct)
+    {
+        var ok = await _tasks.DiscardPlanningAsync(taskId, ct);
+        var sessionDir = Path.Combine(_rootDirectory, taskId);
+        if (Directory.Exists(sessionDir))
+        {
+            try { Directory.Delete(sessionDir, recursive: true); }
+            catch { /* best effort */ }
+        }
+        if (!ok)
+            throw new InvalidOperationException($"Task {taskId} was not in Planning state; nothing to discard.");
+    }
+
     public async Task<PlanningSessionResumeContext> ResumeAsync(string taskId, CancellationToken ct)
     {
         var task = await _tasks.GetByIdAsync(taskId, ct)
diff --git a/tests/ClaudeDo.Worker.Tests/Planning/PlanningSessionManagerTests.cs b/tests/ClaudeDo.Worker.Tests/Planning/PlanningSessionManagerTests.cs
index a587d89..daf1712 100644
--- a/tests/ClaudeDo.Worker.Tests/Planning/PlanningSessionManagerTests.cs
+++ b/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);
+    }
 }
\ No newline at end of file