Now that Halloween is over I was hoping that https://api.guildwars2.com/v2/achievements/categories/79 would simply return an empty list of achievements. It seems to still show them even though none can be achieved.
Can you please make it return an empty array while Halloween is not active?
Soon, winter's day will probably behave the same. Since special dailies seem to be handled like the living world dailies now this would be useful for apps to automatically detect if these categories are active.