from __future__ import annotations

from typing import Optional


def format_runtime_unavailable_detail(
    *,
    label: str,
    fallback: str,
    import_error: Optional[str] = None,
) -> str:
    normalized_error = str(import_error or "").strip()
    if normalized_error:
        return f"{label} is unavailable: {normalized_error}"
    return fallback