Tell HN: My fish died because of CoderPad

5 RomanPushkin 1 7/2/2025, 11:07:20 PM
I'm not writing this to be dramatic - just wanted to share something that happened, and maybe it'll be useful to someone.

I have a small apartment with a few fish tanks. When one of my fish gets sick, I move it to a separate "quarantine" tank where I can monitor it more closely — especially water temperature, which can spike due to direct sunlight.

To help with this, I built a small JavaScript script that runs in my browser via TamperMonkey. It reads from a temperature sensor (via a local API) and plays a loud alert sound if things get too hot. It's not fancy, but it's worked fine for months. I'm not a hardware or desktop dev — the web is my platform, and this was my DIY solution.

Some time ago, I had a two-hour technical interview using CoderPad. I stayed focused in the browser tab the whole time. At some point, the alert I normally hear when things go wrong didn't go off. When I finished the interview, I checked - the quarantine tank had overheated, and the fish didn't make it.

After digging a bit, I suspect what happened is this: CoderPad (or something in its environment) intercepts and blocks fetch calls from browser scripts. Maybe to prevent AI helpers or tampering, I'm not sure. But my alert system relied on those fetch calls to read from the temperature sensor. During the interview, those calls silently failed, and I never got the warning.

So now I'm left wondering: who's at fault here? Me, for building something fragile? CoderPad, for blocking browser functionality in the name of test integrity? Or maybe it's just one of those weird, sad intersections of code and real life :(

Anyway. Just needed to tell someone.

Comments (1)

CamperBob2 · 11h ago
Bummer. :( I wouldn't beat myself up over it, but you should take the lesson for everything it's worth: it's always risky to put a PC or any other cheap complex device in a critical real-time control role. Even when "real time" implies a lag time of an hour or more.

A good cautionary tale in fail-safe design. You're now a better aquarist and a better engineer. Go forth and sin no more. :-P