fix(delegation): integrate lifecycle refactor with tool-history + daemon pool

Follow-ups on the salvaged #63359:
- _finalize_child_results carries tool_call_history on subagent_stop
  (the #62011/#72403 field landed after the PR branched; the shared
  pipeline must emit it for both delegate_task and plugin-launched
  children). Lifecycle test updated for the new payload field.
- The lifecycle executor uses DaemonThreadPoolExecutor — a wedged or
  abandoned child must never block interpreter exit at atexit-join time
  (same rationale as _run_single_child's timeout executor and the
  async-delegation pool).
- delegate_task's batch path keeps live-transcript wiring while routing
  child construction through the shared
  _build_child_preserving_parent_tools helper.

agent/subagent_lifecycle.py

@@ -156,7 +156,12 @@ class _Registry:
 
 
 _REGISTRY = _Registry()
-_EXECUTOR = ThreadPoolExecutor(max_workers=8, thread_name_prefix="hermes-lifecycle")
+# Daemon worker pool: a wedged/abandoned child must never block interpreter
+# exit at atexit-join time (same rationale as _run_single_child's timeout
+# executor and the async-delegation registry pool).
+from tools.daemon_pool import DaemonThreadPoolExecutor as _DaemonExecutor
+
+_EXECUTOR = _DaemonExecutor(max_workers=8, thread_name_prefix="hermes-lifecycle")
 _SECRET = secrets.token_bytes(32)
 _ACTIVE_PARENT_AGENT: contextvars.ContextVar[Any] = contextvars.ContextVar(
     "hermes_subagent_lifecycle_parent", default=None

tests/agent/test_subagent_lifecycle.py

@@ -202,6 +202,10 @@ def test_public_lifecycle_runs_host_aggregation(monkeypatch):
         child_role="leaf",
         child_summary="aggregated",
         child_status="completed",
+        # Redacted tool history rides the shared finalization pipeline
+        # (#62011/#72403); empty here because the fabricated result carries
+        # no tool_trace.
+        tool_call_history=[],
         duration_ms=250,
     )
     assert parent.session_estimated_cost_usd == 3.5