How do biters pick machines to attack?

[cinnamon]

setting up another mining outpost, biters are selecting the miners without any pollution production from the miners. why?

[mmmPI]

When the pollution has been emited and is a red cloud on the map view, the game no longer keep track of which machine produced it, so when that cloud touches some biters, they won't necessarily attack the actual machine that produced the pollution, they will seek what i believe is the closest target given their pathfinding, such target being machines that "could have" produced pollution, or any legitimate target, like they may have ignored power poles in the way, because those can't emit pollution and are only destroyed when they block the way or as collateral damages. From experience and observation, though there may be subtlety i missed, i have no memory of the actual code.

[cinnamon]

yeah, this is the first map i entered "randomly" without checking so theres no trees around, i was used to having biters attack much later, often when defenses are already built, so i was confused by the attacks on random machines