fix: defer scratch workspace cleanup when task has active children (#33774)

When a Kanban task with workspace_kind=scratch completes, the
_cleanup_workspace() function immediately deletes the workspace
directory. If the task has children linked via task_links, those
children find the workspace deleted when they start.

This fix adds two checks:
1. Before deleting, check if any children are still active
   (todo/ready/running). If so, defer cleanup.
2. After a child completes, check if parent workspace can now
   be cleaned up (all children terminal).

Fixes NousResearch/hermes-agent#33774

hermes_cli/kanban_db.py

@@ -3839,6 +3839,23 @@ def _cleanup_workspace(conn: sqlite3.Connection, task_id: str) -> None:
         path: Optional[str] = row["workspace_path"]
         if kind != "scratch" or not path:
             return
+        # Check if this task has children that still need the workspace.
+        # If any child is not yet done/archived, defer cleanup so the
+        # child can read handoff artifacts from the scratch dir (#33774).
+        _active_children = conn.execute(
+            "SELECT 1 FROM task_links l "
+            "JOIN tasks t ON t.id = l.child_id "
+            "WHERE l.parent_id = ? AND t.status NOT IN ('done', 'archived', 'failed', 'cancelled') "
+            "LIMIT 1",
+            (task_id,),
+        ).fetchone()
+        if _active_children:
+            _log.debug(
+                "Deferring scratch workspace cleanup for task %s: "
+                "active children still need workspace at %s",
+                task_id, path,
+            )
+            return
         import shutil
         wp = Path(path)
         if wp.is_dir():
@@ -3860,10 +3877,54 @@ def _cleanup_workspace(conn: sqlite3.Connection, task_id: str) -> None:
         # Also kill the tmux session for the worker that owned this task,
         # if the tmux session is now dead (worker process exited).
         _cleanup_worker_tmux(conn, task_id)
+        # After cleaning up this task's workspace, check if any parent
+        # tasks now have all children done — their deferred cleanup can
+        # proceed (#33774).
+        _try_cleanup_parent_workspaces(conn, task_id)
     except Exception:
         pass  # best-effort — never block completion
 
 
+def _try_cleanup_parent_workspaces(conn: sqlite3.Connection, task_id: str) -> None:
+    """Clean up parent scratch workspaces now that *task_id* completed.
+
+    When a parent task's cleanup was deferred because it had active children,
+    this function is called after each child completes.  If all children of a
+    parent are now done/archived/failed/cancelled, the parent's scratch
+    workspace is removed (#33774).
+    """
+    try:
+        parents = conn.execute(
+            "SELECT parent_id FROM task_links WHERE child_id = ?",
+            (task_id,),
+        ).fetchall()
+        for (parent_id,) in parents:
+            row = conn.execute(
+                "SELECT workspace_kind, workspace_path FROM tasks WHERE id = ?",
+                (parent_id,),
+            ).fetchone()
+            if not row or row["workspace_kind"] != "scratch" or not row["workspace_path"]:
+                continue
+            # Check if ALL children of this parent are terminal
+            active = conn.execute(
+                "SELECT 1 FROM task_links l "
+                "JOIN tasks t ON t.id = l.child_id "
+                "WHERE l.parent_id = ? AND t.status NOT IN ('done', 'archived', 'failed', 'cancelled') "
+                "LIMIT 1",
+                (parent_id,),
+            ).fetchone()
+            if active:
+                continue  # still has active children
+            # All children done — safe to clean up parent workspace
+            import shutil
+            wp = Path(row["workspace_path"])
+            if wp.is_dir() and _is_managed_scratch_path(wp):
+                shutil.rmtree(wp, ignore_errors=True)
+                _log.debug("Deferred cleanup: removed parent %s scratch workspace: %s", parent_id, wp)
+    except Exception:
+        pass  # best-effort
+
+
 def _cleanup_worker_tmux(conn: sqlite3.Connection, task_id: str) -> None:
     """Kill the tmux session associated with a task's assignee, if dead."""
     try: