Atrekes: a used-phone check the buyer can trust

The problem

A used phone can cost a month's wages, and the buyer gets five minutes on a footpath to decide. A battery that has lost half its life looks new. A dead patch on the touchscreen passes if you never touch it there.

The plan I wrote

The app runs shop-style checks on the phone being sold — touch, screen, battery capacity, storage and sensors — and warns when the phone's software has been tampered with.

Then the seller's phone passes the result to the buyer's phone through a QR code, signed, so the buyer knows it came from that phone and is not a screenshot of a better one. It never prices the phone, never rates the seller, and never says whether to buy.

The build

AI coding agents built it from my written specification. My work was the specification, the tests it had to pass, and the review.

The proof

On a real phone — a Samsung Galaxy Z Flip4 on Android 16 — the signed release build ran the full seven-part check twice from a cold start: all 96 touch cells, six live sensors, battery capacity, storage and every screen, with zero crashes in the logs.

When the app had no reference data for that phone model, it said so plainly instead of inventing a match.

The launch

Live on Google Play, with its store listing, privacy page and screenshots for phones and tablets.