"""No network or provider key. The runtime supplies private file paths."""
import json
import os
from pathlib import Path

source = Path(os.environ["ESF_INPUT_PATH"]).read_bytes()
if len(source) > 32 * 1024:
    raise ValueError("Input is too large.")
data = json.loads(source)
if not isinstance(data, dict) or not isinstance(data.get("prompt"), str) or not data["prompt"].strip():
    raise ValueError("A prompt is required.")
Path(os.environ["ESF_OUTPUT_PATH"]).write_text(
    json.dumps({"text": "Received: " + data["prompt"]}, ensure_ascii=False), encoding="utf-8"
)