HutVigil alpine hut availability dataset: nightly bed availability and observed state changes across the Swiss, Austrian, German, Italian and French Alps

Bed availability for around 700 alpine huts of the SAC/CAS, DAV, ÖAV, AVS, CAI and SAT, plus the Chamonix guides' huts, collected by HutVigil from the operators' own public booking systems. The deposit holds two linked tables. availability_daily.csv is a census: one row per hut per night, with the reported status (available, nearly full, fully booked, closed) and, where the operator exposes it, the exact number of free places. state_changes.csv is the longitudinal series: every observed change of state, with its UTC timestamp. The alpine clubs publish a live state per hut but never the aggregate and never a history, so to our knowledge this is the only openly published record of alpine hut occupancy over time. Known limits, please read before analysing. Availability is read from booking systems, so a hut that takes no online booking appears as permanently full or absent. "Closed" means outside the guarded season or not bookable, not fully booked. Sampling is periodic and uneven — flagship huts are polled far more often than the long tail — so any statistic about how long a released bed survives, or about the hour of day when cancellations happen, measures the polling schedule rather than the world unless the sampling interval is established first. In state_changes.csv, an empty old_status marks a first sighting, not a transition. The bundled README documents each pitfall. No personal data: the export reads huts, dates and statuses only.