Create an entity that can have only one instance in the world at a time?

[loud pasture]

A wandering trader seems to behave like this. Is there a flag I need to set to make it work?

[brisk frost]

I don’t think there is a flag that is set I think it’s just that it only spawns once in awhile like every half hour and despawns within a few minutes so that’s why you almost never see two but I have definitely gotten two or more to be spawned in a area

[loud pasture]

I swear I recall seeing something somewhere about how 2 traders cannot exist at the same time. Like, maybe the game checks to see if there is one spawned and prevents the spawn rules from summoning another.

I'd like something that prevents even /summon from creating extras. Ideally it'd be a warning saying "more than 1 [entity] cannot exist at a time".

I could make the entity, on spawn, /kill all other entities of it's kind...

Are custom kill messages allowed? That would work if I can obscure the killing of others

[crimson hollow]

All the mob code is in the vanilla pack. Perhaps read the bp file for him to see if you can see anything that indicates this.

[brisk frost]

yeah I checked and there's no code for that not all of the entity's code is in the vanilla bp yet some entity's code needs updating or needs adding

now /summon will always spawn as many as you want that's just a vanilla thing but you could make a function to kill extras if you don't want people to spawn extra
now even though the wandering trader doesn't appear to have a spawn limit other mobs use minecraft:density_limit you could set it to a low value for your spawn rules that should limit the amount that can spawn

[loud pasture]

Thanks! I will dig into the spawn rules to make the entity naturally spawn only once. Sounds like it's doable at least 🙂