Been There

Been There solves a small but persistent annoyance with vanilla explorer 
maps: nothing tells you if you've already visited the location a treasure 
map points to. Buy a map from a cartographer, explore the structure, then 
months later buy another map from a different villager pointing to the 
same place — and you won't know until you've wasted time traveling there.

Been There tracks every treasure location you've explored and marks 
matching maps automatically:

Features:
- Explored maps in your inventory get a visual checkmark and a renamed 
  label, visible at a glance in your inventory or hotbar
- Villager trade offers for maps pointing to locations you've already 
  explored are marked directly in the trading screen — before you spend 
  a single emerald
- Configurable detection radius, so exploration is recognized even for 
  large structures like woodland mansions (I took the pictures with 10 and 20 blocks)
- Matches by both location and structure type to avoid false positives
- No dependencies, no Mixins — built entirely on public data components 
  and vanilla map data

Built for NeoForge 1.21.1.