Key modification

[PolarisLiu1]

This is a very solid piece of work! I want to know what the key modifications to the code based on search-r1 are, as I couldn't find the part where the mask is applied.

[BobbyZhouZijian]

Hi. Thank you for your question! The mask is generated in this file

https://github.com/MIT-MI/MEM1/blob/main/Mem1/train/rollout/llm_agent/attn_mask_utils.py