refactor(worker): add worktree path and token file helpers

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

src/ClaudeDo.Worker/Planning/PlanningSessionManager.cs

@@ -203,4 +203,54 @@ public sealed class PlanningSessionManager
         sb.AppendLine("Please analyze this task and break it down into concrete subtasks.");
         return sb.ToString();
     }
+
+    private static string BranchNameFor(string taskId) =>
+        $"claudedo/planning/{taskId.Replace("-", "")}";
+
+    private string WorktreePathFor(string taskId, string strategy, string? centralRootOverride, string listWorkingDir)
+    {
+        var centralRoot = !string.IsNullOrWhiteSpace(centralRootOverride)
+            ? centralRootOverride!
+            : _cfg.CentralWorktreeRoot;
+
+        var raw = strategy.Equals("central", StringComparison.OrdinalIgnoreCase)
+            ? Path.Combine(centralRoot, "planning", taskId)
+            : Path.Combine(Path.GetDirectoryName(listWorkingDir)!, ".claudedo-worktrees", "planning", taskId);
+
+        return Path.GetFullPath(raw);
+    }
+
+    private static string TokenFilePathFor(string sessionDir) =>
+        Path.Combine(sessionDir, "token");
+
+    private static async Task WriteTokenFileAsync(string path, string token, CancellationToken ct)
+    {
+        await File.WriteAllTextAsync(path, token, ct);
+        // Best-effort current-user-only ACL on Windows. On non-Windows the inherited
+        // perms from the parent dir apply; acceptable because sessionDir is already
+        // under the user's home (~/.todo-app/sessions/).
+        if (OperatingSystem.IsWindows())
+        {
+            try
+            {
+                var fi = new FileInfo(path);
+                var ac = fi.GetAccessControl();
+                ac.SetAccessRuleProtection(isProtected: true, preserveInheritance: false);
+                var me = System.Security.Principal.WindowsIdentity.GetCurrent().User!;
+                ac.AddAccessRule(new System.Security.AccessControl.FileSystemAccessRule(
+                    me,
+                    System.Security.AccessControl.FileSystemRights.FullControl,
+                    System.Security.AccessControl.AccessControlType.Allow));
+                fi.SetAccessControl(ac);
+            }
+            catch { /* ACL hardening is best-effort */ }
+        }
+    }
+
+    private static async Task<string> ReadTokenFileAsync(string path, CancellationToken ct)
+    {
+        if (!File.Exists(path))
+            throw new InvalidOperationException($"Token file missing: {path}");
+        return (await File.ReadAllTextAsync(path, ct)).Trim();
+    }
 }