import re


def quote_identifier(identifier: str) -> str:
    if not re.fullmatch(r"[A-Za-z_][A-Za-z0-9_]*", identifier):
        raise ValueError(f"Unsafe SQL identifier: {identifier}")
    return f'"{identifier}"'


def vector_literal(embedding: list[float]) -> str:
    return "[" + ",".join(f"{value:.8f}" for value in embedding) + "]"