import asyncpg


async def read_up_to(pool: asyncpg.Pool, account_id: int, chat_id: int) -> int | None:
    return await pool.fetchval(
        "SELECT max(message_id) FROM read_receipts "
        "WHERE account_id = $1 AND chat_id = $2 AND kind = 'read'",
        account_id,
        chat_id,
    )