From 40210917c29f30bf4de1c4d06e051a5efe5ddbd4 Mon Sep 17 00:00:00 2001
From: Bohdan Triapitsyn <artmore@protonmail.com>
Date: Thu, 21 May 2026 13:00:37 +0300
Subject: [PATCH] fix(ui): keep completed reasoning collapsed

---
 .../src/components/chat/message/parts/ReasoningPart.tsx   | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/packages/ui/src/components/chat/message/parts/ReasoningPart.tsx b/packages/ui/src/components/chat/message/parts/ReasoningPart.tsx
index e36505cd..59797252 100644
--- a/packages/ui/src/components/chat/message/parts/ReasoningPart.tsx
+++ b/packages/ui/src/components/chat/message/parts/ReasoningPart.tsx
@@ -89,12 +89,14 @@ export const ReasoningTimelineBlock: React.FC<ReasoningTimelineBlockProps> = ({
     variant,
     onContentChange,
     blockId,
+    time,
     isStreaming = false,
     actions,
     defaultExpanded,
 }) => {
     const { t } = useI18n();
-    const [isExpanded, setIsExpanded] = React.useState(defaultExpanded ?? isStreaming);
+    const hasEnded = typeof time?.end === 'number';
+    const [isExpanded, setIsExpanded] = React.useState(hasEnded ? false : (defaultExpanded ?? isStreaming));
     const contentId = React.useId();
     const scrollRef = React.useRef<HTMLElement>(null);
     const contentRef = React.useRef<HTMLDivElement>(null);
@@ -126,10 +128,10 @@ export const ReasoningTimelineBlock: React.FC<ReasoningTimelineBlockProps> = ({
         prevIsStreamingRef.current = isStreaming;
         // Auto-collapse only when streaming ends (true → false).
         // Do not fire on mount so that defaultExpanded is respected.
-        if (wasStreaming && !isStreaming) {
+        if (hasEnded || (wasStreaming && !isStreaming)) {
             setIsExpanded(false);
         }
-    }, [isStreaming]);
+    }, [hasEnded, isStreaming]);
 
     React.useEffect(() => {
         if (text.trim().length === 0) {