Trying to figure out a possible process map for going through the planet types, and spent some time doing this:
Not quite sure how difficult the branching thing after the first mirror/shade would be to implement though.
If it's going to be to complicated you could just push all types through terran eccentric like now, and have the other cat3s just feed in to that.
I've tried to make it as simple as I can, with each 'tier' of planet feeding into the next. So all the harsh planets merge into the barren. And then into each successive hab tier after that.
The first mirror/shade placement could possibly be moved further back if needed, but the second mirror/shade needs to be after hab3 so it can pick up any hot/cold habitable planets.
All types are accounted for, but this is not stricly nescessary. Would definitely add some polish later on if you could randomise the results of terraforming to cat_barren, and to cat3 (where applicable).
Seeing that chart makes me realize that terraforming everything into Terran worlds is honestly a bit boring. Personally, I'd rather have that second to last column with the 5 habitable worlds be the final (planet) stage, and then further advancement can just add a solar shade/mirror condition to cancel out cold/hot hazards - i.e. your Tundra planet
would be cold, but solar mirrors have resulted in a
Faroe Islands like climate. Similarly, an Arid or Jungle world would be drier or heavily forested than average, respectively, but solar shades keep them from being hot enough to be hazardous.