"""
Per-request logging context.

Carries the request id (the same one `RequestIDMiddleware` puts on the
`X-Request-ID` header) into every log record via a ContextVar + logging.Filter,
so a whole request's log lines can be grepped by one id — essential when
watching the live API.
"""

import contextvars
import logging

# Default "-" so non-request logs (startup, background agents) still format cleanly.
_request_id: contextvars.ContextVar[str] = contextvars.ContextVar("request_id", default="-")


def set_request_id(request_id: str) -> None:
    _request_id.set(request_id or "-")


def get_request_id() -> str:
    return _request_id.get()


class RequestIdFilter(logging.Filter):
    """Injects `request_id` onto every LogRecord so the format string can use it."""

    def filter(self, record: logging.LogRecord) -> bool:
        record.request_id = _request_id.get()
        return True