Initial commit: 浼佷笟寰俊 AI 鏈哄櫒浜哄姪鐞?MVP

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/session_service.py

@@ -0,0 +1,30 @@
+"""会话与消息入库；仅存 public 可见内容，隔离内部信息。"""
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import ChatSession, Message
+
+
+async def get_or_create_session(
+    db: AsyncSession,
+    external_user_id: str,
+    external_name: str | None = None,
+) -> ChatSession:
+    r = await db.execute(select(ChatSession).where(ChatSession.external_user_id == external_user_id))
+    row = r.scalar_one_or_none()
+    if row:
+        if external_name is not None and row.external_name != external_name:
+            row.external_name = external_name
+            await db.flush()
+        return row
+    session = ChatSession(external_user_id=external_user_id, external_name=external_name or None)
+    db.add(session)
+    await db.flush()
+    return session
+
+
+async def add_message(db: AsyncSession, session_id: int, role: str, content: str) -> Message:
+    msg = Message(session_id=session_id, role=role, content=content)
+    db.add(msg)
+    await db.flush()
+    return msg