from pathlib import Path
import re


def normalize_markdown(text: str) -> str:
    text = text.replace("\r\n", "\n").replace("\r", "\n")
    lines = [line.rstrip() for line in text.split("\n")]
    text = "\n".join(lines).strip()
    return re.sub(r"\n{3,}", "\n\n", text)


def load_markdown(path: str | Path) -> str:
    path = Path(path)
    if not path.exists():
        raise FileNotFoundError(f"Markdown file not found: {path}")
    if path.suffix.lower() != ".md":
        raise ValueError(f"Input must be a Markdown .md file: {path}")
    return normalize_markdown(path.read_text(encoding="utf-8"))