fix: instant scroll on session switch, scroll on transcript reflection

Matthias Nott

2026-03-07 5700a2d3c3dc409a8bde3cfa971beeb9b897435f

 components/chat/MessageList.tsx
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@@ -13,14 +13,23 @@
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 export function MessageList({ messages, isTyping, onDeleteMessage }: MessageListProps) {
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   const listRef = useRef<FlatList<Message>>(null);
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+  const prevLengthRef = useRef(0);
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+
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+  // Track the last message's content so transcript reflections trigger a scroll
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+  const lastContent = messages.length > 0 ? messages[messages.length - 1].content : "";
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   useEffect(() => {
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     if (messages.length > 0) {
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+      // If the message count changed by more than 1, it's a session switch —
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+      // snap to bottom instantly instead of visibly scrolling down.
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+      const delta = Math.abs(messages.length - prevLengthRef.current);
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+      const animated = delta === 1;
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       setTimeout(() => {
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-        listRef.current?.scrollToEnd({ animated: true });
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+        listRef.current?.scrollToEnd({ animated });
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       }, 50);
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     }
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-  }, [messages.length, isTyping]);
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+    prevLengthRef.current = messages.length;
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+  }, [messages.length, isTyping, lastContent]);
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   // Play from a voice message and auto-chain all consecutive assistant voice messages after it
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   const handlePlayVoice = useCallback(async (messageId: string) => {
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@@ -61,9 +70,6 @@
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         />
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       )}
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       contentContainerStyle={{ paddingVertical: 12 }}
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-      onContentSizeChange={() => {
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-        listRef.current?.scrollToEnd({ animated: false });
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-      }}
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       showsVerticalScrollIndicator={false}
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       ListFooterComponent={
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         <>