first commit

backend/app/data/repository.py

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+"""K 线数据访问（从库读）。
+
+写入由 DataProvider 适配器负责（阶段1 接 Tushare/AKShare）。
+MVP 的数据由 synthetic.seed_if_empty 灌入。
+"""
+from __future__ import annotations
+
+from datetime import datetime
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from ..models import Candle
+
+
+async def get_candles(
+    session: AsyncSession,
+    symbol: str,
+    timeframe: str = "1d",
+    start: datetime | None = None,
+    end: datetime | None = None,
+    limit: int = 5000,
+) -> list[Candle]:
+    stmt = select(Candle).where(
+        Candle.symbol == symbol,
+        Candle.timeframe == timeframe,
+    )
+    if start is not None:
+        stmt = stmt.where(Candle.ts >= start)
+    if end is not None:
+        stmt = stmt.where(Candle.ts <= end)
+    stmt = stmt.order_by(Candle.ts.asc()).limit(limit)
+    result = await session.execute(stmt)
+    return list(result.scalars().all())