"""
BlockARModel – now unified with SADModel.

BlockARModel is an alias for SADModel. They share the same architecture,
SoftAncestorHierarchy, SADLoss, NoisyStateBuilder, and SADTrainer.

Differences handled externally:
  - Training: SADTrainer is called with truncated sequences (curriculum)
  - Inference: BlockARAdaptiveSkipSampler in src/eval/sampler.py uses
               model.forward_causal() for block-by-block generation

`build_block_diff_mask` is kept here for backward compatibility with tests.
"""

from .sad_model import SADModel, build_block_diff_mask

# Alias so old import paths keep working
BlockARModel = SADModel

__all__ = ["BlockARModel", "SADModel", "build_block_diff_mask"]