Calculate messages for openai completion once

Before the patch, we were calculating them on every retry attempt. The
function is pure, so there is no good reason to repeat the calculation.

This also simplifies the function a bit.

Signed-off-by: Ihar Hrachyshka <[email protected]>

pyproject.toml

@@ -96,3 +96,6 @@ from-first = true
 # import-heading-firstparty=First Party
 # import-heading-localfolder=Local
 known-local-folder = ["tuning"]
+
+[tool.mypy]
+ignore_missing_imports = true

src/instructlab/eval/mt_bench_common.py

@@ -4,7 +4,7 @@
 """
 
 # Standard
-from typing import Optional
+from typing import Optional, TypedDict
 import ast
 import dataclasses
 import glob
@@ -14,6 +14,7 @@
 import time
 
 # Third Party
+from fastchat import conversation
 from fastchat.model.model_adapter import get_conversation_template  # type: ignore
 import openai
 
@@ -254,23 +255,44 @@ def _is_fatal_openai_error(e: openai.OpenAIError) -> bool:
     return isinstance(e, openai.APIConnectionError)
 
 
+# TODO: copied from instructlab (cli) utils module; consolidate somewhere?
+class Message(TypedDict):
+    """
+    Represents a message within an AI conversation.
+    """
+
+    content: str
+    # one of: "user", "assistant", or "system"
+    role: str
+
+
+def _get_messages(
+    conv: conversation.Conversation, merge_system_user_message: bool
+) -> list[Message]:
+    messages = conv.to_openai_api_messages()
+    if (
+        merge_system_user_message
+        and messages[0]["role"] == "system"
+        and messages[1]["role"] == "user"
+    ):
+        messages[1]["content"] = messages[0]["content"] + "\n" + messages[1]["content"]
+        return messages[1:]
+    return messages
+
+
 def chat_completion_openai(
-    openai_client, model, conv, temperature, max_tokens, merge_system_user_message=False
+    openai_client,
+    model,
+    conv: conversation.Conversation,
+    temperature,
+    max_tokens,
+    merge_system_user_message: bool = False,
 ) -> str:
     output = None
+    messages = _get_messages(conv, merge_system_user_message)
 
     for i in range(API_MAX_RETRY):
         try:
-            messages = conv.to_openai_api_messages()
-            if (
-                merge_system_user_message
-                and messages[0]["role"] == "system"
-                and messages[1]["role"] == "user"
-            ):
-                messages[1]["content"] = (
-                    messages[0]["content"] + "\n" + messages[1]["content"]
-                )
-                messages = messages[1:]
             response = openai_client.chat.completions.create(
                 model=model,
                 messages=messages,