diff --git a/src/ClaudeDo.Worker/Planning/PlanningAggregator.cs b/src/ClaudeDo.Worker/Planning/PlanningAggregator.cs
index 73c90b72..b9ab7f42 100644
--- a/src/ClaudeDo.Worker/Planning/PlanningAggregator.cs
+++ b/src/ClaudeDo.Worker/Planning/PlanningAggregator.cs
@@ -133,15 +133,29 @@ public sealed class PlanningAggregator
         var current = await _git.GetCurrentBranchAsync(repoDir, ct);
         if (string.Equals(current, branch, StringComparison.Ordinal))
         {
-            var branches = await _git.ListLocalBranchesAsync(repoDir, ct);
-            var target = branches.FirstOrDefault(b => b != branch && !b.StartsWith("claudedo/", StringComparison.Ordinal)) ?? "main";
-            await _git.CheckoutBranchAsync(repoDir, target, ct);
+            await _git.CheckoutBranchAsync(repoDir, await ResolveReturnBranchAsync(planning, repoDir, ct), ct);
         }
 
         try { await _git.BranchDeleteAsync(repoDir, branch, force: true, ct); }
         catch { /* already gone — idempotent */ }
     }
 
+    /// <summary>
+    /// Rücksprung vom Integration-Branch: <c>list_config.base_branch</c>, sonst <c>main</c> (bzw. <c>master</c>).
+    /// Nie aus der Branchliste raten — die enthält auch Task-Branches, die in Worktrees ausgecheckt sind.
+    /// </summary>
+    private async Task<string> ResolveReturnBranchAsync(TaskEntity planning, string repoDir, CancellationToken ct)
+    {
+        using var ctx = _dbFactory.CreateDbContext();
+        var baseBranch = await ctx.ListConfigs.AsNoTracking()
+            .Where(c => c.ListId == planning.ListId)
+            .Select(c => c.BaseBranch)
+            .FirstOrDefaultAsync(ct);
+        if (!string.IsNullOrWhiteSpace(baseBranch)) return baseBranch;
+        var branches = await _git.ListLocalBranchesAsync(repoDir, ct);
+        return !branches.Contains("main") && branches.Contains("master") ? "master" : "main";
+    }
+
     private async Task<(TaskEntity planning, string repoDir, IReadOnlyList<TaskEntity> children)>
         LoadPlanningContextAsync(string planningTaskId, CancellationToken ct)
     {
diff --git a/src/ClaudeDo.Worker/Runner/WorktreeManager.cs b/src/ClaudeDo.Worker/Runner/WorktreeManager.cs
index ca8762a3..7b6540a2 100644
--- a/src/ClaudeDo.Worker/Runner/WorktreeManager.cs
+++ b/src/ClaudeDo.Worker/Runner/WorktreeManager.cs
@@ -243,9 +243,6 @@ public sealed class WorktreeManager
         _logger.LogInformation("Discarded worktree for task {TaskId} (branch {Branch})", wt.TaskId, wt.BranchName);
     }
 
-    // Improvement children (parent is a non-planning task with its own worktree) branch
-    // from the parent's recorded HEAD so they build on the parent's not-yet-merged work.
-    // Planning children and standalone tasks base off the list's current HEAD.
     /// <summary>Ticket-Id des Tasks, sonst die seines Parents (Children erben das Ticket ihrer Unit).</summary>
     private async Task<int?> ResolveTicketIdAsync(TaskEntity task, CancellationToken ct)
     {
@@ -259,6 +256,9 @@ public sealed class WorktreeManager
         return TicketStatusMap.ParseBandelTicketId(parentRef);
     }
 
+    // Improvement children (parent is a non-planning task with its own worktree) branch
+    // from the parent's recorded HEAD so they build on the parent's not-yet-merged work.
+    // Planning children and standalone tasks base off list_config.base_branch, else the current HEAD.
     private async Task<string> ResolveBaseCommitAsync(TaskEntity task, string workingDir, CancellationToken ct)
     {
         if (task.ParentTaskId is not null)
diff --git a/tests/ClaudeDo.Worker.Tests/Planning/PlanningAggregatorTests.cs b/tests/ClaudeDo.Worker.Tests/Planning/PlanningAggregatorTests.cs
index a1ccaea8..299c1864 100644
--- a/tests/ClaudeDo.Worker.Tests/Planning/PlanningAggregatorTests.cs
+++ b/tests/ClaudeDo.Worker.Tests/Planning/PlanningAggregatorTests.cs
@@ -214,6 +214,39 @@ public class PlanningAggregatorTests : IDisposable
         Assert.DoesNotContain(branches, b => b == ok.Value.IntegrationBranch);
     }
 
+    [Theory]
+    [InlineData(null, "main")]
+    [InlineData("dev", "dev")]
+    public async Task CleanupIntegrationBranchAsync_ReturnsToBaseBranchOrMain_NotATaskBranch(string? baseBranch, string expected)
+    {
+        var db = NewDb();
+        var repo = NewRepo();
+        GitRepoFixture.RunGit(repo.RepoDir, "branch", "-m", "main");
+        GitRepoFixture.RunGit(repo.RepoDir, "branch", "dev");
+        var (parentId, _, _) = await SeedPlanningWithTwoChildrenAsync(db, repo);
+
+        // Sorts before main and is checked out in a worktree — the old guess picked it and the checkout threw.
+        var taskWt = Path.Combine(Path.GetTempPath(), $"wt_{Guid.NewGuid():N}");
+        _wtCleanups.Add((repo.RepoDir, taskWt));
+        GitRepoFixture.RunGit(repo.RepoDir, "worktree", "add", "-b", "chore/1-task", taskWt, repo.BaseCommit);
+
+        if (baseBranch is not null)
+        {
+            using var ctx = db.CreateContext();
+            var listId = (await new TaskRepository(ctx).GetByIdAsync(parentId))!.ListId;
+            await new ListRepository(ctx).SetConfigAsync(new ListConfigEntity { ListId = listId, BaseBranch = baseBranch });
+        }
+
+        var git = new GitService();
+        var svc = new PlanningAggregator(db.CreateFactory(), git, NullLogger<PlanningAggregator>.Instance);
+        var built = Assert.IsType<CombinedDiffResult.Ok>(await svc.BuildIntegrationBranchAsync(parentId, "main", CancellationToken.None));
+        Assert.Equal(built.Value.IntegrationBranch, await git.GetCurrentBranchAsync(repo.RepoDir));
+
+        await svc.CleanupIntegrationBranchAsync(parentId, CancellationToken.None);
+
+        Assert.Equal(expected, await git.GetCurrentBranchAsync(repo.RepoDir));
+    }
+
     private void SeedWorktreeWithFile(ClaudeDoDbContext ctx, GitRepoFixture repo, string taskId, string filename, string content)
     {
         var wtPath = Path.Combine(Path.GetTempPath(), $"wt_{Guid.NewGuid():N}");