AlcoTrack

AlcoTrack was the first thing I ever built. I was at school in 2012 with my first Android phone, learning to code, and I wanted to make something my friends and I would actually use instead of another task manager or weather app. Fourteen years later it still has users.

It also still had a codebase a teenager had started in Eclipse, which newer Android versions were making steadily more obvious. So it was rebuilt: Kotlin, Compose, Hilt and Room, with a migration path so nobody lost a decade of their own history, plus the tooling that should have been there from the start, screenshot tests and automated publishing. The original does not ship any more.

The part worth talking about is the coach, a chat inside the app that answers questions about your own drinking data. Getting it to answer was easy. Getting it to stop overclaiming was not, and the failure mode was sneakier than plain hallucination. It would pull one real number correctly, then wrap it in a detail no tool had ever checked. A true fact and an invented one in the same sentence, in the same confident tone.

The fix turned out to be plumbing rather than prompting. Every tool now returns the scope of what it actually looked at, so an answer cannot cite data it never fetched, and a test replays real conversations against the live model and fails the build when it overclaims. With an agent like this the interesting work is not the model or the system prompt. It is the guardrails that make its confidence earned.

The rest is mine as well: store listing, screenshots, support mail, and the 17 community translations from people who just wanted the app in their own language.