- Use model_copy(update=...) in test helpers so Pydantic ge=
validators are enforced during tests, not just env vars (NEW-1)
- Promote _extract_plan_id_from_sandbox to public staticmethod
and reuse in CLI active-plan detection to eliminate duplicate
plan-ID parsing logic (NEW-2)
- Cache _get_sandbox_dirs result for service instance lifetime
and have CLI active-plan detection use the cached listing so
/tmp is iterated only once per invocation (NEW-3)
khyari hamza