tracker.batch

:meth:`BatchTracker.step` runs either a per-slot fallback loop or, when :meth:`is_vmap_safe` holds and the root is :class:`Pipe(_, Associate)`, a batched LAP solve via :func:`auto_batch_assignment`. The opt-in :meth:`BatchTracker.predict_and_cost_vmap` runs the predict and cost-production phase under :func:`torch.func.vmap`; end-to-end vmap currently trips a tensordict-internal unbind limitation tracked by xfail tests in ``tests/unitrack/tracker/test_batch_vmap.py``.