What does xtuner do?
Add or audit an XTuner chat-template implementation and its loss mask from an official Hugging Face model repository or local model directory. Use when supporting a new model under xtuner/v1/data_proto/messages, checking an existing implementation against tokenizer or processor apply_chat_template, deciding which assistant output and stop/EOS tokens receive loss, adding regression tests, or validating that exported training behavior matches vLLM and SGLang inference.