The original note, as written at the time
A way of taking landscape photographs but with a portrait orientation of the phone, for taking high resolution landscape images discretely.
Ongoing development
A way of taking landscape photographs while holding the phone in portrait, so a high-resolution wide image can be captured discretely.
Two things are being solved at once and only one of them is about photography.
The technical one is straightforward and underused: the sensor is usually wider than the default capture, so a portrait hold can still record a landscape frame. Turn the phone and you lose nothing, because the crop happens afterwards. Most people never discover this because the interface assumes the orientation of the hand.
The social one is the reason it matters. Holding a phone sideways is an announcement. It says I am photographing this, it brings the device up to the face, and it changes the room. Holding it upright, thumb on the shutter, is the same posture as reading a message, and a person can record a market, a street, a room of people behaving naturally, without becoming the event.
That is not only about discretion in the awkward sense. It is about the difference between a photograph of people and a photograph of people posing, and every photographer knows the second is worth less.
The design work is entirely in the framing aid. If the preview shows a landscape crop inside a portrait screen, the photographer composes properly and the feature is honest. If it just crops afterwards, people will cut off heads.
And there is a documentary argument I would make loudly: the most valuable images of a city are the unposed ones, and the barrier to unposed is the gesture. Make the gesture ordinary and the record changes.