fix(ui): use parentID matching instead of positional scan for assistant messages (#23093)

packages/ui/src/components/session-turn.tsx

@@ -267,14 +267,12 @@ export function SessionTurn(
       if (!msg) return emptyAssistant
 
       const messages = allMessages() ?? emptyMessages
-      const index = messageIndex()
-      if (index < 0) return emptyAssistant
+      if (messageIndex() < 0) return emptyAssistant
 
       const result: AssistantMessage[] = []
-      for (let i = index + 1; i < messages.length; i++) {
+      for (let i = 0; i < messages.length; i++) {
         const item = messages[i]
         if (!item) continue
-        if (item.role === "user") break
         if (item.role === "assistant" && item.parentID === msg.id) result.push(item as AssistantMessage)
       }
       return result