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name: agent-studio-chat description: Work on Agent Studio chat (UI + streaming) and the /api/chat route. Use for tasks like message rendering, reasoning display, editing/regenerate, Zustand chat stores, model/settings UI, and OpenRouter or Vercel AI SDK integration. 聊天功能开发/排障：流式输出、Reasoning 展示、消息编辑与重新生成、模型与参数设置。

Agent Studio Chat

Follow the data flow

• Start from src/components/features/chat/hooks/useChatLogic.ts (Vercel AI SDK useChat + DefaultChatTransport).
• Server route is src/app/api/chat/route.ts (OpenRouter provider + streamText).
• UI entry is src/components/features/chat/ChatInterface.tsx (Virtuoso list + ChatInput).

Know the state layers

• Conversation persistence: src/lib/store/useChatStore.ts
• UI-only transient state (editing/copy): src/lib/store/useChatUIStore.ts
• Model + sampling + system instructions: src/lib/store/useSettingsStore.ts and src/components/features/settings/SettingsPanel.tsx

Make safe changes

• Preserve UIMessage.parts when needed (reasoning parts may carry provider metadata; see src/app/api/chat/route.ts).
• Prefer adding new transient UI flags to useChatUIStore to avoid prop drilling.
• Keep feature code under src/components/features/chat/ and reuse src/components/ui/* primitives.