fix for openai compatibility model with needed parameters

services/rag/llamaindex/chat_engine.py

@@ -17,6 +17,7 @@ from typing import Any, Iterable, List
 
 from llama_index.core import PromptTemplate
 from llama_index.core.agent import AgentWorkflow
+from llama_index.core.base.llms.types import ChatMessage, MessageRole
 from llama_index.core.retrievers import VectorIndexRetriever
 from llama_index.core.schema import NodeWithScore
 from llama_index.core.tools import FunctionTool
@@ -230,6 +231,19 @@ def synthesize_answer(query: str, sources: list[dict[str, Any]], agent_draft: st
         context_json=context_json,
     )
     logger.info("Synthesizing grounded answer from retrieved sources")
+    # Prefer chat API for chat-capable models; fallback to completion if unavailable.
+    try:
+        if hasattr(llm, "chat"):
+            chat_response = llm.chat(
+                [
+                    ChatMessage(role=MessageRole.SYSTEM, content="You answer with grounded citations only."),
+                    ChatMessage(role=MessageRole.USER, content=prompt),
+                ]
+            )
+            return _normalize_text(getattr(chat_response, "message", chat_response).content)
+    except Exception as e:
+        logger.warning(f"LLM chat synthesis failed, falling back to completion: {e}")
+
     response = llm.complete(prompt)
     return _normalize_text(getattr(response, "text", response))