From dc81abcc011e6fa72dc1ba5cf3f4024ee9855d23 Mon Sep 17 00:00:00 2001
From: Danny Avila <danny@librechat.ai>
Date: Thu, 18 Dec 2025 09:52:27 -0500
Subject: [PATCH] refactor: useResumableStreamToggle hook to manage resumable
 streams for legacy/assistants endpoints

- Introduced a new hook, useResumableStreamToggle, to automatically toggle resumable streams off for assistants endpoints and restore the previous value when switching away.
- Updated ChatView component to utilize the new hook, enhancing the handling of streaming behavior based on endpoint type.
- Refactored imports in ChatView for better organization.
---
 client/src/components/Chat/ChatView.tsx       | 13 +++++-
 client/src/hooks/SSE/index.ts                 |  1 +
 .../src/hooks/SSE/useResumableStreamToggle.ts | 41 +++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 client/src/hooks/SSE/useResumableStreamToggle.ts

diff --git a/client/src/components/Chat/ChatView.tsx b/client/src/components/Chat/ChatView.tsx
index 9275496734..c6eb25d546 100644
--- a/client/src/components/Chat/ChatView.tsx
+++ b/client/src/components/Chat/ChatView.tsx
@@ -7,7 +7,13 @@ import { Constants, buildTree } from 'librechat-data-provider';
 import type { TMessage } from 'librechat-data-provider';
 import type { ChatFormValues } from '~/common';
 import { ChatContext, AddedChatContext, useFileMapContext, ChatFormProvider } from '~/Providers';
-import { useChatHelpers, useAddedResponse, useAdaptiveSSE, useResumeOnLoad } from '~/hooks';
+import {
+  useResumableStreamToggle,
+  useAddedResponse,
+  useResumeOnLoad,
+  useAdaptiveSSE,
+  useChatHelpers,
+} from '~/hooks';
 import ConversationStarters from './Input/ConversationStarters';
 import { useGetMessagesByConvoId } from '~/data-provider';
 import MessagesView from './Messages/MessagesView';
@@ -50,6 +56,11 @@ function ChatView({ index = 0 }: { index?: number }) {
   const chatHelpers = useChatHelpers(index, conversationId);
   const addedChatHelpers = useAddedResponse({ rootIndex: index });
 
+  useResumableStreamToggle(
+    chatHelpers.conversation?.endpoint,
+    chatHelpers.conversation?.endpointType,
+  );
+
   useAdaptiveSSE(rootSubmission, chatHelpers, false, index);
 
   // Auto-resume if navigating back to conversation with active job
diff --git a/client/src/hooks/SSE/index.ts b/client/src/hooks/SSE/index.ts
index 2829db76f6..800de1e2a7 100644
--- a/client/src/hooks/SSE/index.ts
+++ b/client/src/hooks/SSE/index.ts
@@ -5,3 +5,4 @@ export { default as useResumeOnLoad } from './useResumeOnLoad';
 export { default as useStepHandler } from './useStepHandler';
 export { default as useContentHandler } from './useContentHandler';
 export { default as useAttachmentHandler } from './useAttachmentHandler';
+export { default as useResumableStreamToggle } from './useResumableStreamToggle';
diff --git a/client/src/hooks/SSE/useResumableStreamToggle.ts b/client/src/hooks/SSE/useResumableStreamToggle.ts
new file mode 100644
index 0000000000..f14fde044a
--- /dev/null
+++ b/client/src/hooks/SSE/useResumableStreamToggle.ts
@@ -0,0 +1,41 @@
+import { useEffect, useRef } from 'react';
+import { useRecoilState } from 'recoil';
+import { isAssistantsEndpoint } from 'librechat-data-provider';
+import type { EModelEndpoint } from 'librechat-data-provider';
+import store from '~/store';
+
+/**
+ * Automatically toggles resumable streams off for assistants endpoints
+ * and restores the previous value when switching away.
+ *
+ * Assistants endpoints have their own streaming mechanism and don't support resumable streams.
+ */
+export default function useResumableStreamToggle(
+  endpoint: EModelEndpoint | string | null | undefined,
+  endpointType?: EModelEndpoint | string | null,
+) {
+  const [resumableStreams, setResumableStreams] = useRecoilState(store.resumableStreams);
+  const savedValueRef = useRef<boolean | null>(null);
+  const wasAssistantsRef = useRef(false);
+
+  useEffect(() => {
+    const actualEndpoint = endpointType ?? endpoint;
+    const isAssistants = isAssistantsEndpoint(actualEndpoint);
+
+    if (isAssistants && !wasAssistantsRef.current) {
+      // Switching TO assistants: save current value and disable
+      savedValueRef.current = resumableStreams;
+      if (resumableStreams) {
+        setResumableStreams(false);
+      }
+      wasAssistantsRef.current = true;
+    } else if (!isAssistants && wasAssistantsRef.current) {
+      // Switching AWAY from assistants: restore saved value
+      if (savedValueRef.current !== null) {
+        setResumableStreams(savedValueRef.current);
+        savedValueRef.current = null;
+      }
+      wasAssistantsRef.current = false;
+    }
+  }, [endpoint, endpointType, resumableStreams, setResumableStreams]);
+}