K2 (or SE? But certainly K2+SE) uses shallow water (Via Alien Biomes I believe). This planner will try and place stuff on the water where it can't go. I'm not an expert in the tiles system but it'd be great to have that taken into account. Thanks much!

Repro - create a map using Alien Biomes, use the planner on a patch that spawns near water. You'll know the shallow water because you can walk through it.

Sorry for the late reply. I'm pretty sure it was always accounted for.
The landfill step retrieves all tiles with collision mask "water-tile" and attempts to place landfill there.
Shallow water tile "water-shallow" has "water-tile" collision mask so it's properly handled.

There's a landfill ghost on shallow water tile.

No worries, thanks for the response! I didn't see the landfill tiles but I see them now, it makes sense.

Small request then - have an option to not place landfill. I'm one of the weirdos who likes building around terrain. I'd rather have to take a 2nd pass at mining layout than have landfill placed around the shoreline. It's a nitpick, I know :)

Thanks for the mod!