From 115a081420f27babd77333d78df99bf82d657993 Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Wed, 27 May 2026 00:21:10 +0000
Subject: [PATCH] fix(types): declare sequence_number on Responses API
 streaming events

Pydantic-extra storage works at runtime but mypy (with pydantic.mypy)
treats undeclared constructor kwargs as call-arg errors. Declare
sequence_number explicitly on the event classes used by the Responses
API streaming iterator so the type checker accepts the kwarg and
allows setattr on OutputTextAnnotationAddedEvent.
---
 litellm/types/llms/openai.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/litellm/types/llms/openai.py b/litellm/types/llms/openai.py
index abe58199dfd..b770eb6b47d 100644
--- a/litellm/types/llms/openai.py
+++ b/litellm/types/llms/openai.py
@@ -1448,16 +1448,19 @@ class ResponsesAPIStreamEvents(str, Enum):
 class ResponseCreatedEvent(BaseLiteLLMOpenAIResponseObject):
     type: Literal[ResponsesAPIStreamEvents.RESPONSE_CREATED]
     response: ResponsesAPIResponse
+    sequence_number: int = 0
 
 
 class ResponseInProgressEvent(BaseLiteLLMOpenAIResponseObject):
     type: Literal[ResponsesAPIStreamEvents.RESPONSE_IN_PROGRESS]
     response: ResponsesAPIResponse
+    sequence_number: int = 0
 
 
 class ResponseCompletedEvent(BaseLiteLLMOpenAIResponseObject):
     type: Literal[ResponsesAPIStreamEvents.RESPONSE_COMPLETED]
     response: ResponsesAPIResponse
+    sequence_number: int = 0
     _hidden_params: dict = PrivateAttr(default_factory=dict)
 
 
@@ -1484,6 +1487,7 @@ class ReasoningSummaryTextDeltaEvent(BaseLiteLLMOpenAIResponseObject):
     output_index: int
     summary_index: int = 0
     delta: str
+    sequence_number: int = 0
 
 
 class ReasoningSummaryTextDoneEvent(BaseLiteLLMOpenAIResponseObject):
@@ -1508,6 +1512,7 @@ class OutputItemAddedEvent(BaseLiteLLMOpenAIResponseObject):
     type: Literal[ResponsesAPIStreamEvents.OUTPUT_ITEM_ADDED]
     output_index: int
     item: Optional[BaseLiteLLMOpenAIResponseObject]
+    sequence_number: int = 0
 
 
 class OutputItemDoneEvent(BaseLiteLLMOpenAIResponseObject):
@@ -1536,6 +1541,7 @@ class ContentPartAddedEvent(BaseLiteLLMOpenAIResponseObject):
     output_index: int
     content_index: int
     part: BaseLiteLLMOpenAIResponseObject
+    sequence_number: int = 0
 
 
 class ContentPartDonePartOutputText(BaseLiteLLMOpenAIResponseObject):
@@ -1568,6 +1574,7 @@ class ContentPartDoneEvent(BaseLiteLLMOpenAIResponseObject):
     output_index: int
     content_index: int
     part: PART_UNION_TYPES
+    sequence_number: int = 0
 
 
 class OutputTextDeltaEvent(BaseLiteLLMOpenAIResponseObject):
@@ -1576,6 +1583,7 @@ class OutputTextDeltaEvent(BaseLiteLLMOpenAIResponseObject):
     output_index: int
     content_index: int
     delta: str
+    sequence_number: int = 0
 
 
 class OutputTextAnnotationAddedEvent(BaseLiteLLMOpenAIResponseObject):
@@ -1585,6 +1593,7 @@ class OutputTextAnnotationAddedEvent(BaseLiteLLMOpenAIResponseObject):
     content_index: int
     annotation_index: int
     annotation: dict
+    sequence_number: int = 0
 
 
 class OutputTextDoneEvent(BaseLiteLLMOpenAIResponseObject):
@@ -1616,6 +1625,7 @@ class FunctionCallArgumentsDeltaEvent(BaseLiteLLMOpenAIResponseObject):
     item_id: str
     output_index: int
     delta: str
+    sequence_number: int = 0
 
 
 class FunctionCallArgumentsDoneEvent(BaseLiteLLMOpenAIResponseObject):
@@ -1623,6 +1633,7 @@ class FunctionCallArgumentsDoneEvent(BaseLiteLLMOpenAIResponseObject):
     item_id: str
     output_index: int
     arguments: str
+    sequence_number: int = 0
 
 
 class FileSearchCallInProgressEvent(BaseLiteLLMOpenAIResponseObject):