Poll a booking

Poll every few seconds until terminal is true. The poll is also how LetsFG knows you are still there, which keeps a booking paused on a question alive.

States: authorised, card_issued, booking_in_progress, awaiting_settlement, then completed (with pnr and charged_amount), failed (hold released, nothing charged) or needs_attention (a human at LetsFG is on it — do not book again).

A declined payment is failed with decline_reason, decline_message and decline_advice - and, when the same payment went on as 3-D Secure, retry {booking_id, pay_url}. That retry booking reads awaiting_payment with pay_url and awaiting_link_payment until the traveller's bank approves the payment on pay_url, then starts by itself and walks the states above.

While booking_in_progress, question may carry a seat map, a paid extra or a fare increase; answer it through POST /flights/bookings/{booking_id}/answer within its window or the run continues without it.