Support default chat template kwargs

[sufubao]

No description provided.

[gemini-code-assist]

Code Review

This pull request introduces a new CLI argument --default_chat_template_kwargs to specify default JSON keyword arguments for the chat template tokenizer, which are merged with request-specific arguments when building prompts and determining reasoning modes. Unit tests are also added to verify this functionality. The reviewer suggests making the get_effective_chat_template_kwargs helper function more robust by defensively checking types and using getattr on the request object to prevent potential runtime errors.

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[gemini-code-assist]

To prevent potential runtime errors (such as AttributeError or TypeError), it is safer to defensively check that default_chat_template_kwargs and request.chat_template_kwargs are indeed dictionaries before calling .update(). Additionally, using getattr on request ensures compatibility if a request object without the chat_template_kwargs attribute is passed (e.g., in certain testing scenarios or alternative request flows).

Suggested change

	def get_effective_chat_template_kwargs(request) -> dict:
	kwargs = {}
	default_kwargs = getattr(get_env_start_args(), "default_chat_template_kwargs", None)
	if default_kwargs:
	kwargs.update(default_kwargs)
	if request.chat_template_kwargs:
	kwargs.update(request.chat_template_kwargs)
	return kwargs
	def get_effective_chat_template_kwargs(request) -> dict:
	kwargs = {}
	default_kwargs = getattr(get_env_start_args(), "default_chat_template_kwargs", None)
	if isinstance(default_kwargs, dict):
	kwargs.update(default_kwargs)
	req_kwargs = getattr(request, "chat_template_kwargs", None)
	if isinstance(req_kwargs, dict):
	kwargs.update(req_kwargs)
	return kwargs