For several days, my service was quietly broken and every health check said it was fine.
No exceptions. No 5xx. No alerts. The upstream API returned 200 OK the entire time. What it stopped returning was half the payload — and nothing in my stack was built to notice the difference.
This is a short write-up of what happened, how I eventually found it, and the one habit I changed afterwards.
The setup
I build and run a small video downloader. A user pastes a link, the server resolves it, and the browser gets a file. Two paths do that work:
