Cat TrackR: the SureFlap app I actually wanted

My cat Megla (means Misty in Slovene) kills birds. She is very good at it. I needed her inside at dawn and dusk, when the endangered New Zealand birds outside are rubbing their eyes and yawning, and seem to let their guard down.

The SureFlap 'smart' door flap can lock on a schedule. Their app lets you set curfew times. What it does not let you do is tie those times to sunrise and sunset, which is the only thing that actually matters when your cat sees dusk as an open invitation.

So I built Cat TrackR. It took one evening.

The mobile version. Notice how you can see what's happening without tapping through four screens.

Everything came together in a couple of hours with using OpenCode and a few different models, mostly GPT 5.4 since it was so fast and clever at the same time. It's my favorite right now. That may sound like a chore, but I did this while watching TV. Coding with AI is mostly about supervising the AI, guiding when appropriate, but otherwise doing a lot of waiting. It's not much different than any other multi-screening task. It's not nearly as intense as writing code by hand.

Since I could write this by hand, I know how to keep the AI from doing stupid things. AI is a knowledge multiplier rather than a replacement, at least for now. The more you understand how to craft code manually, the faster your AI coding will be.

The SureFlap app is bad

The hardware is fine. Four AA batteries, a microchip reader, a motorized lock. It works.

The app is where things go wrong. It is slow. It is phone-only. And its curfew feature expects you to manually update the lock times as the seasons change, like a gatekeeper for the hunting reserve outside.

Sunrise moves. Sunset moves. Birds don't check your app settings. A curfew that made sense in March is wrong by May. I wanted the flap to just follow the sun. Lock at dusk, unlock at dawn.

The SureFlap app said no. So now there is a whole replacement.

What it does

You tell it where you live. It looks up sunrise and sunset. It pushes lock and unlock times to the flap every day, adjusted for the season. That is the whole point.

It also shows you whether your cat is inside or outside, the battery level, recent flap events, and lets you manually lock things if you need to. It runs on your phone or laptop as a PWA, so you can install it as an app.

Cat TrackR on desktop. Everything the SureFlap app does, minus the parts that annoyed me.

It has an API because why not

It has its own API exposed, so OpenClaw can use it too. You can check on Megla, lock the flap, update curfew settings, all from a script or an agent. There is an OpenAPI spec and everything.

Overkill for a cat flap? Maybe, but with AI doing the work why not add all the mod-cons?

The hard part

The hardest part of this project was not the undocumented SureFlap API. It was making the iPhone PWA splash screen look right. I could have skipped it. I didn't. I am who I am.

The whole thing runs in one Docker container. The repo is at github.com/abort-retry-ignore/Cat-trackR if you also have a cat who needs supervising.

Megla gets a flap that follows the sun. The birds get slightly better odds. And I never have to open the SureFlap app again, which honestly might be the biggest win.