"""JSONL flight recorder — every model call, action, and test run is an event."""

from __future__ import annotations

import datetime
import json
from pathlib import Path


class Session:
    def __init__(self, path: Path):
        self.path = path
        path.parent.mkdir(parents=True, exist_ok=True)
        self._fh = path.open("a")

    def log(self, event: str, **data) -> None:
        record = {
            "ts": datetime.datetime.now(datetime.timezone.utc).isoformat(),
            "event": event,
            **data,
        }
        self._fh.write(json.dumps(record, ensure_ascii=False) + "\n")
        self._fh.flush()

    def close(self) -> None:
        self._fh.close()

    def __enter__(self) -> "Session":
        return self

    def __exit__(self, *exc) -> None:
        self.close()