chore: initialize project repository

app/repository/session_repository.py

@@ -0,0 +1,44 @@
+from datetime import UTC, datetime
+
+from sqlalchemy import select, update
+from sqlalchemy.engine import CursorResult
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.errors import ConflictAgentError, ResourceNotFoundError
+from app.model.session import ConversationSession
+
+
+class SessionRepository:
+    def __init__(self, session: AsyncSession) -> None:
+        self.session = session
+
+    async def owned(
+        self, session_id: str, user_id: int, *, lock: bool = False
+    ) -> ConversationSession:
+        query = select(ConversationSession).where(ConversationSession.session_id == session_id,
+                                                  ConversationSession.user_id == user_id)
+        if lock:
+            query = query.with_for_update()
+        row = await self.session.scalar(query)
+        if row is None:
+            raise ResourceNotFoundError("会话不存在")
+        return row
+
+    async def require_active(self, session_id: str, user_id: int, agent_type: str) -> None:
+        row = await self.owned(session_id, user_id, lock=True)
+        if row.status != "active":
+            raise ConflictAgentError("会话已结束")
+        if row.agent_type != agent_type:
+            raise ConflictAgentError("Agent 与会话不一致")
+        row.message_count += 1
+        row.last_active_at = datetime.now(UTC).replace(tzinfo=None)
+
+    async def advance_clarification(self, session_id: str, expected: int) -> bool:
+        if expected >= 10:
+            return False
+        result = await self.session.execute(update(ConversationSession).where(
+            ConversationSession.session_id == session_id,
+            ConversationSession.clarification_round == expected,
+            ConversationSession.status == "active",
+        ).values(clarification_round=expected + 1))
+        return isinstance(result, CursorResult) and result.rowcount == 1