python -m verl.model_merger merge \
  --backend fsdp \
  --local_dir /mnt/general/wanghy/RAGEN/saves/qwen3b_it_frommlp_nothink_think_sokobanbox1_sequence_multitask/global_step_200/actor \
  --target_dir /mnt/general/wanghy/RAGEN/saves/qwen3b_it_frommlp_nothink_think_sokobanbox1_sequence_multitask/global_step_200/qwen2.5_3b_actor_hf