From a20b60db75aeecde526840c284bd698c70f01e50 Mon Sep 17 00:00:00 2001
From: hzt <3061613175@qq.com>
Date: Fri, 20 Feb 2026 12:20:52 +0800
Subject: [PATCH] fix: reorder chat history sidebar after new message in
 existing chat

When sending a new message in an existing/resumed chat, the thread's
position in the sidebar history list was not updated. This happened
because the first_interaction event only fires once per session, so
subsequent messages never triggered a thread list refresh.

Track message count changes and update the active thread's createdAt
timestamp when a new user message is detected, which triggers
groupByDate to re-sort and move the thread to the top of the list.

Fixes #2763
---
 .../components/LeftSidebar/ThreadHistory.tsx  | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/frontend/src/components/LeftSidebar/ThreadHistory.tsx b/frontend/src/components/LeftSidebar/ThreadHistory.tsx
index e7c2bf4866..b1c6ded7ff 100644
--- a/frontend/src/components/LeftSidebar/ThreadHistory.tsx
+++ b/frontend/src/components/LeftSidebar/ThreadHistory.tsx
@@ -30,6 +30,7 @@ export function ThreadHistory() {
   const [isLoadingMore, setIsLoadingMore] = useState(false);
   const [isFetching, setIsFetching] = useState(false);
   const [shouldLoadMore, setShouldLoadMore] = useState(false);
+  const prevMessageCountRef = useRef(0);
 
   // Restore scroll position
   useEffect(() => {
@@ -60,6 +61,35 @@ export function ThreadHistory() {
     handleFirstInteraction();
   }, [firstInteraction]);
 
+  // Reorder thread to top when a new message is sent in the current thread
+  useEffect(() => {
+    const currentCount = messages.length;
+    const prevCount = prevMessageCountRef.current;
+    prevMessageCountRef.current = currentCount;
+
+    if (
+      threadId &&
+      currentCount > prevCount &&
+      prevCount > 0 &&
+      threadHistory?.threads
+    ) {
+      const lastMessage = messages[currentCount - 1];
+      if (lastMessage?.type === 'user_message') {
+        setThreadHistory((prev) => {
+          if (!prev?.threads) return prev;
+          const threadIndex = prev.threads.findIndex((t) => t.id === threadId);
+          if (threadIndex <= 0) return prev; // Already at top or not found
+          const updatedThreads = [...prev.threads];
+          updatedThreads[threadIndex] = {
+            ...updatedThreads[threadIndex],
+            createdAt: new Date().toISOString()
+          };
+          return { ...prev, threads: updatedThreads };
+        });
+      }
+    }
+  }, [messages.length, threadId]);
+
   const handleScroll = () => {
     if (!scrollRef.current) return;
     const { scrollHeight, clientHeight, scrollTop } = scrollRef.current;