I built a Snap Specs Lens so new mail carriers can learn their case from memory
My mom has worked at the post office for over 30 years, so when I picked a project for Devpost's Learn AR with SPECS hackathon, I wanted to build something for new carriers. Every route has its own case. It's a wall of
My mom has worked at the post office for over 30 years, so when I picked a project for Devpost's Learn AR with SPECS hackathon, I wanted to build something for new carriers.
Every route has its own case. It's a wall of one-inch slots, and each slot holds one or two addresses. The carrier handbook says to start by memorizing the first two rows, then keep going row by row until you know the whole case. In fiscal 2024, only 40.8% of new city carrier assistants were still on the job a year later (USPS Inspector General, preliminary), so there's always someone new standing at a case they've never seen.
My mom said it better than I can, on camera: "If you don't have a permanent route then they get moved to another route and have to learn all over again."
What it does
Case Light puts a real-size practice case in front of you, labelled with real house numbers from streets near Kennesaw State.
First you practice. You pinch a letter and the right slot lights up. If it's off to the side, an arrow at the edge of your view points to it.
Then you do the same letters again, but the case stays dark. You read the address and put it where you think it goes. If you miss, the right slot lights up and that letter doesn't count. At the end it tells you how many you placed from memory.
It also remembers. The next time you open it, it says "Welcome back" with your last score, and "Show my case" marks each row by what you've actually placed from memory.
When I told my mom about it, she asked how the case would read the addresses. It doesn't. The whole point is that you learn them.
Why glasses
On the real job your hands are full of mail. A phone app would mean putting the mail down to look at a screen. On glasses the case sits in the room at real size, so the slots are where your hands expect them.
How I built it
I planned it first with the Devpost Learn skill pack. Its plan-lens interview turned my answers into a design brief with five done criteria, and those became the first tests.
Then CLAD built and tested it in Lens Studio through the Lens Studio MCP, across 47 sessions and 2,860 MCP calls. LEAF tests it in the preview with 47 scenarios, and I broke the Lens on purpose more than 150 times to make sure each test actually catches its bug.
The agent pushed back on me once and it was right. A full-size printed address is wider than the display at arm's length, so it shrank the letters until a whole address fits.
What I learned
"Done" has to be something you can check. Writing the five criteria first meant every change had something real to test against. I also learned the glasses can't show a whole case at once, which is why the arrow had to be there from day one.
Limits
Everything in the video runs in the Lens Studio preview with simulated hand input. It hasn't run on Specs hardware yet, and working carriers haven't tried it yet. The mail is practice mail on real house numbers, not a real route.
Next I want to get it in front of real carriers. My mom is already asking people she knows.
Originally published by Dev.to AI. Aggregated on AIWithGhost for educational purposes — full credit and traffic to the original publisher.