The Liftie Sutras

Picture a powder morning at Palisades Tahoe. Hundreds of people stand in a line that is not moving, because the Tram and the Funitel, the two gate lifts the upper mountain hangs from, are on hold. No sign says why or for how long. Operators follow rules nobody ever published, and real life is full of rules like that. Software archaeology usually digs unwritten rules out of old code. We dug these out of the operators' own posts: 7,044 of them across eight winters, matched to weather readings. A parser we wrote read every post. Two independent readers, Subquadratic and Meta Muse, labeled the same posts without seeing the parser's answers, and we used the places where they disagreed with it to find and fix parser errors. Then we hid each winter in turn. The gust speed where wind holds begin, learned without that winter, landed within 2.4 mph of 60 mph all eight times, and it called each hidden winter's wind-hold days better than a 25 mph rule (balance score 0.70 to 0.88, against 0.38 to 0.72). When a gate lift holds, 47% of the upper mountain holds with it; when no gate holds, 6%. About four in ten holds come with no stated cause. We show those as missing pages, and we say where a plain wind line beats our per-lift rules. The Liftie Sutras is a working tool: replay any past morning and compare the rules' calls with what the operators did, or set the wind and snow yourself, including three possible 2026-27 El Niño days (possibilities, not forecasts). Live: https://evmonaha880.github.io/tahoe-lift-rulebook/app/