Help finding an old concept; natural RAW result being magocratic city-states

[Mechalich]

What was the source for resetting traps? It's a cornerstone to the entire concept, but I've never been clear if it was core or splat.

It's perfectly possible to do the Tippyverse without automatic resetting traps, it just requires a greater degree of dumpster diving for items. For example, you can provide infinite food using an Everful Larder.