Hi,
Spidertron are often wandering too far from base or just go slighty outside of walls and ends in an undesired encounter with biters
they dont seem to go very far outside (or they just got mauled before they could do so)

I looked up but i cant see any setting to constraint them
maybe a drag and drop tool to delimit where they can go when they're idling idk
or a fallback in the middle of the base in case of an attack

very good mod nonetheless !

Thanks for the report - I will look into it. This mod should not be sending spiders into enemy territory.
I don't want to get too technical, but perhaps if I explain a little how they work you can help me get the spiders to behave.
Basically every so often they look around for something interesting to wander off to. If they find something (built by the player), they also check that it's not on the "ignored entity list", so i.e. walls, gates, vehicles, power poles, rails are not valid targets (stuff that might be placed outside the "safety zone" of the general factory area).
Could you tell me a little about your walls, or if you have any idea what the spiders are trying to get to when they wander out into enemy territory?

We did not see it happen live but it happened at least 5 times

the base is quite vast but not dense, and we dont use artillery on our wall
always just outside the walls (i'll try to send images of the game)
we also use the spidertron mk2 /3 mods (cant recall if a vanilla spidertron got this issue, the only ghosts we have left are mk2s )

I have a theory, buts its quite a stretch:
maybe they wanted to stop before but they go too fast and end up doing so right when a attack occurs and get caught in cross fire ?
i dont have access to what their grid looked like prior to death in their ghosts

A̶n̶d̶ t̶o̶ t̶h̶e̶ w̶h̶y̶ t̶h̶e̶y̶ d̶o̶ w̶a̶n̶d̶e̶r̶ t̶o̶ h̶e̶r̶e̶, i̶ t̶h̶i̶n̶k̶ t̶h̶e̶y̶ l̶o̶v̶e̶ a̶c̶c̶u̶m̶u̶l̶a̶t̶o̶r̶s̶,
w̶e̶ f̶i̶l̶l̶e̶d̶ t̶h̶e̶ i̶n̶s̶i̶d̶e̶ o̶f̶ o̶u̶r̶ 2̶w̶a̶y̶s̶ r̶a̶i̶l̶s̶ w̶i̶t̶h̶ a̶c̶c̶u̶m̶u̶l̶a̶t̶o̶r̶s̶ a̶n̶d̶ t̶h̶a̶t̶s̶ l̶i̶k̶e̶ 4̶8̶ K̶ o̶f̶ t̶h̶e̶m̶ ?̶
(̶w̶h̶y̶ a̶ b̶i̶g̶ r̶o̶b̶o̶t̶ s̶p̶i̶d̶e̶r̶ w̶o̶u̶l̶d̶n̶t̶ l̶i̶k̶e̶ j̶u̶i̶c̶y̶ a̶c̶c̶u̶m̶u̶l̶a̶t̶o̶r̶ ?̶ :̶]̶ )̶
that cant be it (not good with lua here but yeah you excludes them too)

its also a 2 player game idk if that would change much

the images
https://ibb.co/FbXps7ZK : the death locations are green circles
https://ibb.co/wZdpHP7M : a close up of one dead spidertron

https://ibb.co/ZRq6rBR1: not directly related but there is also this mk2 that is stuck trying to reach an island on gleba

edit: we also use spidertron enhancements! forgot about this one
edit2: typos/format

still with extended spidertron and spidertron enhancement:
tried with a vanilla spidertron and same results
looking into the ignored entities lists and looking at my walls:
I cant think of anything apart from either land mines or concrete

or laser and flamethrowers turret arent included in the "turret" entity

Thank you so much for the explanation and images!
It's interesting that they seem to by dying right on the outside of the wall, actually I think your theory is not too far off. And considering that the pathfinder goal has a 10-tile radius around the target entity that it can find a path to, it may be pathfinding to the landmines and overshooting them a little, or potentially even pathfinding to the flamethrower pipes.
Laser and flamethrower turrets should both count as "turret" due to how the code works, but I'll also double-check that just in case.
For now, I'm going to release an update that adds landmines to the ignored entities list, because that seems the most likely culprit here and I think it was an oversight on my part not to include them in the list originally. I am aiming to have that uploaded some time tonight when I get home.
I am also considering ways to overclock that poor little fish of a brain and have the spiders run away if they are under attack. I won't make any promises about if or when that will happen, but I'm thinking about how it might work :)