first commit

llm_runtime/util_chat.py

@@ -0,0 +1,23 @@
+from typing import Any, Dict, List, Optional
+
+def apply_chat_template(tokenizer, messages: List[Dict[str, str]], add_generation_prompt: bool = True) -> str:
+    """Apply chat template to messages using tokenizer or fallback to ChatML format"""
+    if hasattr(tokenizer, "apply_chat_template"):
+        return tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=add_generation_prompt)
+    
+    # Fallback: simple ChatML-ish format
+    parts = []
+    for m in messages:
+        role = m.get("role", "user")
+        content = m.get("content", "")
+        if role == "system":
+            parts.append(f"<|system|>\n{content}\n")
+        elif role == "assistant":
+            parts.append(f"<|assistant|>\n{content}\n")
+        else:
+            parts.append(f"<|user|>\n{content}\n")
+    
+    if add_generation_prompt:
+        parts.append("<|assistant|>\n")
+    
+    return "".join(parts)