Use tokenizer chat template for tiny prompts

app.py

@@ -318,8 +318,9 @@ def build_prompt(processor_obj, user_text: str) -> str:
             ],
         }
     ]
-    if hasattr(processor_obj, "apply_chat_template"):
-        return processor_obj.apply_chat_template(messages, add_generation_prompt=True)
+    tokenizer = getattr(processor_obj, "tokenizer", None)
+    if tokenizer is not None and hasattr(tokenizer, "apply_chat_template"):
+        return tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
     return f"<image>\n{user_text}"