fix(kanban): give each subtask its own worktree instead of inheriting parent path (#53983)

tests/tools/test_kanban_tools.py

@@ -798,6 +798,36 @@ def test_create_inherits_worker_dir_workspace(monkeypatch, worker_env):
         conn.close()
 
 
+def test_create_worktree_subtask_gets_own_path(monkeypatch, worker_env):
+    """A worker scoped to a worktree task that spawns a child should give
+    the child its own workspace_path, not the parent's worktree dir."""
+    from tools import kanban_tools as kt
+    from hermes_cli import kanban_db as kb
+
+    parent_wt = "/tmp/fake-worktree"
+    conn = kb.connect()
+    try:
+        self_tid = kb.create_task(
+            conn, title="wt worker", assignee="test-worker",
+            workspace_kind="worktree", workspace_path=parent_wt,
+        )
+        kb.claim_task(conn, self_tid)
+    finally:
+        conn.close()
+    monkeypatch.setenv("HERMES_KANBAN_TASK", self_tid)
+
+    d = json.loads(kt._handle_create({"title": "wt child", "assignee": "peer"}))
+    assert d["ok"] is True
+    conn = kb.connect()
+    try:
+        child = kb.get_task(conn, d["task_id"])
+        assert child.workspace_kind == "worktree"
+        # The child must NOT inherit the parent's worktree path.
+        assert child.workspace_path != parent_wt
+    finally:
+        conn.close()
+
+
 def test_create_explicit_workspace_beats_inheritance(monkeypatch, worker_env):
     """An explicit workspace arg overrides worker-task inheritance."""
     from tools import kanban_tools as kt

tools/kanban_tools.py

@@ -823,7 +823,13 @@ def _handle_create(args: dict, **kw) -> str:
                     _self_task = kb.get_task(conn, _self_tid)
                     if _self_task is not None and _self_task.workspace_kind:
                         workspace_kind = _self_task.workspace_kind
-                        workspace_path = _self_task.workspace_path
+                        # For worktree workspaces, don't inherit the parent's
+                        # path — each subtask needs its own worktree so
+                        # concurrent workers don't collide on the same
+                        # directory.  create_task will derive a fresh
+                        # <repo>/.worktrees/<task-id> from the project repo.
+                        if workspace_kind != "worktree":
+                            workspace_path = _self_task.workspace_path
                         # Keep follow-up children inside the same project so the
                         # whole subtree shares one repo + branch convention.
                         if project_id is None and _self_task.project_id: