Worked on improving tokenizer stability within the meta-llama/PurpleLlama repository, focusing on the Llama-Prompt-Guard component. Addressed a persistent issue where incorrect regex warnings appeared during tokenizer loading by introducing the fix_mistral_regex parameter to the AutoTokenizer.from_pretrained() calls. This targeted bug fix, implemented in Python using the HuggingFace Transformers library, eliminated unnecessary runtime warnings and enhanced the reliability of production deployments. The work involved careful debugging, patch engineering, and thorough code review, resulting in smoother deployment pipelines and more predictable model prompting behavior. Demonstrated skills in machine learning, natural language processing, and in-repo tooling throughout the process.