feat：优化流式输出，增加临时多轮对话记录

app/schemas/conversation.py

@@ -0,0 +1,27 @@
+"""会话及对话轮次，用于多轮上下文和后续持久化"""
+
+from datetime import datetime
+from typing import Literal
+
+from pydantic import BaseModel
+
+
+class Turn(BaseModel):
+    """一次任务对应一轮对话，同一个 thread_id 多次写入时覆盖同一轮"""
+
+    conversation_id: str
+    thread_id: str
+    message_id: str
+    prompt: str  # 用户原始输入
+    outcome: Literal["completed", "waiting_for_input", "failed", "cancelled"]
+    summary: str  # 助手侧摘要，只描述后端生成了什么，不代表前端已执行
+    created_at: datetime
+
+
+class ConversationCreated(BaseModel):
+    conversation_id: str
+
+
+class ConversationDetail(BaseModel):
+    conversation_id: str
+    turns: list[Turn]