fix: preserve chat kwargs identity when no sanitization is needed

Author: adavyas

run_agent.py

@@ -2354,20 +2354,41 @@ def _build_api_kwargs(self, api_messages: list) -> dict:
 
             return kwargs
 
-        sanitized_messages = copy.deepcopy(api_messages)
-        for msg in sanitized_messages:
+        sanitized_messages = api_messages
+        needs_sanitization = False
+        for msg in api_messages:
             if not isinstance(msg, dict):
                 continue
-
-            # Codex-only replay state must not leak into strict chat-completions APIs.
-            msg.pop("codex_reasoning_items", None)
+            if "codex_reasoning_items" in msg:
+                needs_sanitization = True
+                break
 
             tool_calls = msg.get("tool_calls")
             if isinstance(tool_calls, list):
                 for tool_call in tool_calls:
-                    if isinstance(tool_call, dict):
-                        tool_call.pop("call_id", None)
-                        tool_call.pop("response_item_id", None)
+                    if not isinstance(tool_call, dict):
+                        continue
+                    if "call_id" in tool_call or "response_item_id" in tool_call:
+                        needs_sanitization = True
+                        break
+                if needs_sanitization:
+                    break
+
+        if needs_sanitization:
+            sanitized_messages = copy.deepcopy(api_messages)
+            for msg in sanitized_messages:
+                if not isinstance(msg, dict):
+                    continue
+
+                # Codex-only replay state must not leak into strict chat-completions APIs.
+                msg.pop("codex_reasoning_items", None)
+
+                tool_calls = msg.get("tool_calls")
+                if isinstance(tool_calls, list):
+                    for tool_call in tool_calls:
+                        if isinstance(tool_call, dict):
+                            tool_call.pop("call_id", None)
+                            tool_call.pop("response_item_id", None)
 
         provider_preferences = {}
         if self.providers_allowed: