*** Begin Patch

*** Update File: app/db.py

@@

async def fetch_ohlc_bars(

pool: asyncpg.pool.Pool, symbol: str, timeframe: str, limit: int = 500

) -> list[dict]:

@@

return result

+

+

+async def latest_bar_ts(pool: asyncpg.pool.Pool, symbol: str, timeframe: str):

+ """Return the most recent timestamp we have for a symbol/timeframe, or None."""

+ q = "SELECT ts FROM ohlc_bars WHERE symbol=$1 AND timeframe=$2 ORDER BY ts DESC LIMIT 1"

+ async with pool.acquire() as conn:

+ val = await conn.fetchval(q, symbol, timeframe)

+ return val

*** End Patch