Leaker "pdfu" shared code-level details about the Apple Watch Series 12 and Ultra 4's new AI-powered day summary feature, called "Ambient Sensing." The feature will generate summaries including time, date, location, meal information, and people present with their relationship to the user. The underlying code supports dozens of activity categories, ranging from meal prep and household chores like vacuuming, laundry, and gardening, to workouts such as running, cycling, yoga, and strength training. Commuting activities like driving, flying, and public transit are tracked, along with shopping for groceries, clothes, and home goods.

Screen time categories include using tablets, laptops, desktops, and e-readers, as well as watching TV and reading books. Social and personal activities like family time, meetings, parties, brushing teeth, getting dressed, and attending classes or sermons are also included. A catch-all "Unknown" category covers unclassified actions.

The feature builds on a Bloomberg report by Mark Gurman, who said the system analyzes the day—including conversations—but does not record or store audio or produce transcripts to preserve privacy. Apple Watch Series 12 and Ultra 4 are expected to be announced alongside the iPhone 18 Pro, iPhone 18 Pro Max, and the foldable iPhone Duo.