- RolloutGenerator._instruction_to_messages builds system/user/assistant list (instruction->system, input->user, output->assistant), replacing single-user-turn concatenation
- Remove _iter_samples helper; _prepare_prompts zips parallel list-of-strings fields directly per the collate_fn contract
- Tests adopt a system-aware chat template and pin the three-field role mapping
- Drop unused imports caught by ruff F401 (torch.Tensor in scheduler.py, iter_raw_records in pipeline.py, Tuple in evaluate_rouge.py)
- train_context.py referenced non-existent cfg.batch_size, replaced with cfg.batch_per_device
- default group_size lowered from 8 to 1: without a group concept (DPO), scheduler batch equals batch_per_device; rollout-based DPO can opt in via extra_kwargs['group_size']>=2
- inline expressions (rollout_batch_size, max_seq_len) extracted for readability
- add tests/trainer/test_online_e2e.py: end-to-end online_dpo via Trainer.train, exercising KV-cache-backed rollout path
ViperEkura