Proof of Grass app uses open-source audio model to verify time outdoors, fixes weather bug

A developer created an app called Proof of Grass that uses an open-source audio model, Perch 2.0, to verify if a user has spent time outdoors. The app runs entirely offline on a user's laptop to preserve privacy. During testing, the model initially misidentified rain sounds as human-made noises like vehicles, a bug the developer was able to fix because the model's code is open. The app provides a tamper-proof digital receipt for time spent outside, though it can be fooled and is still being refined.