From e9625ad069920a224be093cede8de0bb1f379c0a Mon Sep 17 00:00:00 2001
From: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Date: Thu, 17 Sep 2026 05:22:09 +0000
Subject: [PATCH] fix(responses): default the message output index when no
 reasoning item exists

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
---
 .../litellm_completion_transformation/streaming_iterator.py     | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/litellm/responses/litellm_completion_transformation/streaming_iterator.py b/litellm/responses/litellm_completion_transformation/streaming_iterator.py
index beffd12a349..71502e33d5c 100644
--- a/litellm/responses/litellm_completion_transformation/streaming_iterator.py
+++ b/litellm/responses/litellm_completion_transformation/streaming_iterator.py
@@ -602,6 +602,8 @@ class LiteLLMCompletionStreamingIterator(ResponsesAPIStreamingIterator):
         if self._cached_reasoning_item_id is not None:
             self._message_output_index = self._next_tool_output_index
             self._next_tool_output_index += 1
+        else:
+            self._message_output_index = 0
         self._sequence_number += 1
         event: Final = OutputItemAddedEvent(
             type=ResponsesAPIStreamEvents.OUTPUT_ITEM_ADDED,