test(worker): cover planning worktree lifecycle and self-heal

Adds four tests to PlanningSessionManagerTests: worktree removal on
discard, error on non-git working dir, self-heal when branch already
exists, and resume returning the correct token and session id.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -218,4 +218,72 @@ public sealed class PlanningSessionManagerTests : IDisposable
         Assert.Equal(TaskStatus.Manual, loaded!.Status);
         Assert.Null(loaded.PlanningSessionToken);
     }
+
+    [Fact]
+    public async Task DiscardAsync_RemovesWorktreeAndBranch()
+    {
+        var (listId, wd) = await SeedListAsync();
+        var parent = await SeedManualTaskAsync(listId);
+
+        var ctx = await _sut.StartAsync(parent.Id, CancellationToken.None);
+        Assert.True(Directory.Exists(ctx.WorktreePath));
+
+        await _sut.DiscardAsync(parent.Id, CancellationToken.None);
+
+        Assert.False(Directory.Exists(ctx.WorktreePath));
+        // branch deleted
+        var paths = await _git.ListWorktreePathsForBranchAsync(wd, ctx.BranchName);
+        Assert.Empty(paths);
+    }
+
+    [Fact]
+    public async Task StartAsync_ThrowsWhenWorkingDirIsNotGitRepo()
+    {
+        var listId = Guid.NewGuid().ToString();
+        var wd = Path.Combine(Path.GetTempPath(), $"cd_nogit_{Guid.NewGuid():N}");
+        Directory.CreateDirectory(wd);
+        await _lists.AddAsync(new ListEntity { Id = listId, Name = "NoGit", WorkingDir = wd, CreatedAt = DateTime.UtcNow });
+
+        var t = await SeedManualTaskAsync(listId);
+
+        await Assert.ThrowsAsync<InvalidOperationException>(() => _sut.StartAsync(t.Id, CancellationToken.None));
+    }
+
+    [Fact]
+    public async Task StartAsync_SelfHealsWhenBranchAlreadyExists()
+    {
+        var (listId, wd) = await SeedListAsync();
+        var parent = await SeedManualTaskAsync(listId);
+
+        // Pre-create a colliding branch.
+        var branch = $"claudedo/planning/{parent.Id.Replace("-", "")}";
+        var head = await _git.RevParseHeadAsync(wd);
+        var procInfo = new System.Diagnostics.ProcessStartInfo("git") { WorkingDirectory = wd };
+        procInfo.ArgumentList.Add("branch");
+        procInfo.ArgumentList.Add(branch);
+        procInfo.ArgumentList.Add(head);
+        var p = System.Diagnostics.Process.Start(procInfo)!;
+        p.WaitForExit();
+
+        var ctx = await _sut.StartAsync(parent.Id, CancellationToken.None);
+        Assert.True(Directory.Exists(ctx.WorktreePath));
+    }
+
+    [Fact]
+    public async Task ResumeAsync_ReturnsContextWithTokenAndWorktree()
+    {
+        var (listId, wd) = await SeedListAsync();
+        var parent = await SeedManualTaskAsync(listId);
+
+        var startCtx = await _sut.StartAsync(parent.Id, CancellationToken.None);
+
+        // Simulate the claude session capturing its session id.
+        await _tasks.UpdatePlanningSessionIdAsync(parent.Id, "session-abc");
+
+        var resumeCtx = await _sut.ResumeAsync(parent.Id, CancellationToken.None);
+
+        Assert.Equal(startCtx.Token, resumeCtx.Token);
+        Assert.Equal(startCtx.WorktreePath, resumeCtx.WorktreePath);
+        Assert.Equal("session-abc", resumeCtx.ClaudeSessionId);
+    }
 }