diff --git a/changelog/4141.added.md b/changelog/4141.added.md
new file mode 100644
index 000000000..a2e65e4c4
--- /dev/null
+++ b/changelog/4141.added.md
@@ -0,0 +1 @@
+- ⚠️ Added WebSocket-based `OpenAIResponsesLLMService` as the new default for the OpenAI Responses API. It maintains a persistent connection to `wss://api.openai.com/v1/responses` and automatically uses `previous_response_id` to send only incremental context, falling back to full context on reconnection or cache miss. The previous HTTP-based implementation is now available as `OpenAIResponsesHttpLLMService`.