"""Structured JSON logging to stderr (spec §12.2)."""
import json
import sys
from datetime import datetime, timezone


def log(event: str, level: str = "info", **fields) -> None:
    record = {
        "timestamp": datetime.now(tz=timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ"),
        "level": level,
        "module": "aissurance",
        "event": event,
        **fields,
    }
    print(json.dumps(record), file=sys.stderr, flush=True)