From c051e3d532f7b3b37ba3a302efef03c7090e4bf1 Mon Sep 17 00:00:00 2001 From: Roland Tannous Date: Sat, 21 Feb 2026 04:40:29 +0000 Subject: [PATCH] fix: load proper vision processor from base model when FastVisionModel returns raw tokenizer, add tokenize=False to vision chat template --- studio/backend/core/inference/inference.py | 126 +++++++++++++-------- 1 file changed, 80 insertions(+), 46 deletions(-) diff --git a/studio/backend/core/inference/inference.py b/studio/backend/core/inference/inference.py index 62b0b031ee..6423e7a128 100644 --- a/studio/backend/core/inference/inference.py +++ b/studio/backend/core/inference/inference.py @@ -107,6 +107,23 @@ class InferenceBackend: # Apply inference optimization FastVisionModel.for_inference(model) + # FastVisionModel may return a raw tokenizer (e.g. GemmaTokenizerFast) + # instead of a proper Processor for some models (e.g. Gemma-3). + # In that case, load the real processor from the base model. + from transformers import ProcessorMixin + if not (isinstance(processor, ProcessorMixin) or hasattr(processor, "image_processor")): + processor_source = config.base_model if config.is_lora else config.identifier + logger.warning( + f"FastVisionModel returned {type(processor).__name__} (no image_processor) " + f"for '{model_name}' — loading proper processor from '{processor_source}'" + ) + from transformers import AutoProcessor + processor = AutoProcessor.from_pretrained( + processor_source, + token=hf_token if hf_token and hf_token.strip() else None, + ) + logger.info(f"Loaded {type(processor).__name__} from {processor_source}") + self.models[model_name]["model"] = model self.models[model_name]["tokenizer"] = processor self.models[model_name]["processor"] = processor @@ -580,55 +597,72 @@ class InferenceBackend: if is_vision and image: # Vision model generation (only when an image is actually provided) - yield from self._generate_vision_response( - messages, system_prompt, image, - temperature, top_p, top_k, min_p, max_new_tokens, repetition_penalty, - cancel_event=cancel_event, + # Check that the stored processor can actually handle images. + # FastVisionModel may return a raw tokenizer (e.g. GemmaTokenizerFast) + # instead of a proper ProcessorMixin for some models (e.g. Gemma-3). + from transformers import ProcessorMixin + processor = model_info.get("processor") + has_image_processing = ( + processor is not None + and (isinstance(processor, ProcessorMixin) or hasattr(processor, "image_processor")) ) - else: - # Text model: Use training pipeline approach - # Messages are already in ChatML format from eval.py - - # Step 1: Apply get_chat_template if model is in mapper - try: - from utils.datasets import MODEL_TO_TEMPLATE_MAPPER, get_tokenizer_chat_template - - model_name_lower = self.active_model_name.lower() - - # Check if model has a registered template - if model_name_lower in MODEL_TO_TEMPLATE_MAPPER: - template_name = MODEL_TO_TEMPLATE_MAPPER[model_name_lower] - logger.info(f"Applying chat template '{template_name}' for {self.active_model_name}") - - # This modifies the tokenizer with the correct template - tokenizer = get_chat_template( - tokenizer, - chat_template=template_name, - ) - else: - logger.info(f"No registered template for {self.active_model_name}, using tokenizer default") - except Exception as e: - logger.warning(f"Could not apply get_chat_template: {e}") - - # Step 2: Format with tokenizer.apply_chat_template() - try: - formatted_prompt = tokenizer.apply_chat_template( - messages, - tokenize=False, - add_generation_prompt=True + if has_image_processing: + yield from self._generate_vision_response( + messages, system_prompt, image, + temperature, top_p, top_k, min_p, max_new_tokens, repetition_penalty, + cancel_event=cancel_event, + ) + return + else: + logger.warning( + f"Model '{self.active_model_name}' is marked as vision but its processor " + f"({type(processor).__name__}) has no image_processor — " + f"falling back to text-only generation (image will be ignored)." ) - logger.debug(f"Formatted prompt: {formatted_prompt[:200]}...") - except Exception as e: - logger.error(f"Error applying chat template: {e}") - # Fallback to manual formatting - formatted_prompt = self.format_chat_prompt(messages, system_prompt) - # Step 3: Generate - yield from self.generate_stream( - formatted_prompt, temperature, top_p, top_k, min_p, max_new_tokens, repetition_penalty, - cancel_event=cancel_event, - _adapter_state=_adapter_state, + # Text path: Use training pipeline approach + # Messages are already in ChatML format from eval.py + + # Step 1: Apply get_chat_template if model is in mapper + try: + from utils.datasets import MODEL_TO_TEMPLATE_MAPPER, get_tokenizer_chat_template + + model_name_lower = self.active_model_name.lower() + + # Check if model has a registered template + if model_name_lower in MODEL_TO_TEMPLATE_MAPPER: + template_name = MODEL_TO_TEMPLATE_MAPPER[model_name_lower] + logger.info(f"Applying chat template '{template_name}' for {self.active_model_name}") + + # This modifies the tokenizer with the correct template + tokenizer = get_chat_template( + tokenizer, + chat_template=template_name, + ) + else: + logger.info(f"No registered template for {self.active_model_name}, using tokenizer default") + except Exception as e: + logger.warning(f"Could not apply get_chat_template: {e}") + + # Step 2: Format with tokenizer.apply_chat_template() + try: + formatted_prompt = tokenizer.apply_chat_template( + messages, + tokenize=False, + add_generation_prompt=True ) + logger.debug(f"Formatted prompt: {formatted_prompt[:200]}...") + except Exception as e: + logger.error(f"Error applying chat template: {e}") + # Fallback to manual formatting + formatted_prompt = self.format_chat_prompt(messages, system_prompt) + + # Step 3: Generate + yield from self.generate_stream( + formatted_prompt, temperature, top_p, top_k, min_p, max_new_tokens, repetition_penalty, + cancel_event=cancel_event, + _adapter_state=_adapter_state, + ) def _generate_vision_response(self, messages, system_prompt, image, temperature, top_p, top_k, min_p, max_new_tokens, @@ -663,7 +697,7 @@ class InferenceBackend: } ] - input_text = processor.apply_chat_template(vision_messages, add_generation_prompt=True) + input_text = processor.apply_chat_template(vision_messages, add_generation_prompt=True, tokenize=False) inputs = processor( image, input_text,