The first nudge I built was an orange glow at the top of the screen. That was all. To find out why it showed, you had to point at it.

Poxture App is a Mac menu-bar app. It checks your posture through the camera and nudges you when a habit holds for a while, like leaning in close to the screen or propping your chin on your hand. In its first 4 weeks I changed that nudge 5 times. Each change below has the problem, the fix and the days it took.

1. The glow didn't say what was wrong

What went wrong: the glow said something was off. It didn't name the habit, and nothing on screen showed how to fix it.

Fix: a card under the glow names the habit and shows the fix. A live meter moves as you correct, so you can see when you're back in range.

Time: 9 days from the first version. It shipped in 0.9.0, on 21 October.

2. The camera light stayed on for hours

What went wrong: on 17 October I made the camera light steady, so it would stop blinking at each check. In daily use it then stayed on for hours. The people testing it read a steady light as a call still running, or as recording.

Fix: by default the camera now comes on for a moment at each check, once a minute. A setting keeps it always on, for people who prefer a steady light.

Time: 4 days after the change, 2 after the testers flagged it. Also in 0.9.0.

That light is the one thing anyone can check without reading my code.

3. There was no clear "fixed"

What went wrong: once you looked away from the card, the only sign was the glow going away. From the user's side, a nudge that just goes away looks like an app that stopped working.

Fix:

  1. 0.11.0 (1 November): the menu-bar figure turns green for a moment when you fix it.
  2. 0.11.6 (9 November): fix your posture while you're using the card, and the card turns green and stays until you're done. If you slip again, the card shows it.

Time: 2 releases, 8 days apart.

4. Closing a nudge didn't close it

What went wrong: in 0.11.0, the × closed the card. The glow stayed, and so did the camera, until you fixed your posture.

Fix: × or Esc now closes the glow too, and the camera goes back to a moment at each check. That habit stays quiet for 10 minutes by default.

Time: the same day. 0.11.0 and 0.11.1 both shipped on 1 November.

5. Some nudges were wrong, and saying so was hard

What went wrong: a camera can be wrong. Someone else walks into view, or it says you're looking down when you weren't. Until November you couldn't quiet just one habit for a while, and a wrong pick didn't keep that habit quiet.

Fix:

  1. 0.11.4 (4 November): Snooze on every card quiets one habit for 15 minutes, 1 hour or until tomorrow. Pick what a nudge got wrong, and that habit stays quiet until you change how you sit, move to another spot, or 15 minutes pass.
  2. 0.11.5 (5 November): every nudge card, monitor tip and setup's Try it step ends with "Think this is wrong? Tell Poxture App", with picks like "Someone else was in view".

Time: 2 releases on back-to-back days.

Under all of it: no pictures

Apple's Vision framework runs on the Mac, so reading posture doesn't need a picture sent anywhere.

Two things hold that line while I keep shipping:

  1. A test fails if any app code can turn a frame into an image or a video.
  2. Live view, the one place you see what the camera reads, draws a stick figure.

The camera question macOS asks on first launch says it in the app's own words: "Each frame is read on this Mac and dropped. No picture is ever sent, saved or shown."

The cost: I can't show you a before-and-after of my own posture from the app.

What I'd build in from the first version

  1. Make every nudge say what's wrong, how to fix it, and when it's fixed.
  2. Put "this is wrong" on the nudge itself, one click away.
  3. Treat the camera light as part of the design.
  4. When close doesn't fully close, fix it the same day.

The app is Poxture App. It needs an Apple Silicon Mac with macOS 15 or later. The first hour of checking each day is free for good, and for your first 14 days every feature works all day. To keep it on all day, $19 once for the first 50 supporters, then $29.

If you've built something that nudges people, how do you show them they've fixed it?