Am I missing something?
I have a few Companions, all have Companion Roboport (and all other Companion items) in grid. One Companion has 6 const bots in its trunk. Companion Roboport is charged. When I send a command (deconstruct trees), my Companions go out, and the one Companion launches its bots, but when they're done they return items to Companion but they don't charge. Companion info screen shows 0 robot charging points (same for Companion Roboport info screen).
Is there tech to unlock it?
Are there any known mod incompatibilities?

I'm using Space Expansion with attendant mods (Including Krastorio2). Mod pack includes AAI Industries, I added Programable vehicles

me too

I think I figured it out. Companion Roboport in the grid of a Companion enables construction lasers (6 lasers each, and 6 semi useless construction bots each). With 1 RX and 4 roboports in Companion grid, the companion gets 24construction lasers and builds faster. It can use construction bots also if they are in the Companion trunk, but...

With character personal roboport enabled, all Companion bots will return to character after the one job. With personal roboports disabled 6 bots per roboport will be used repeatedly until they run out of juice. Then they will just follow sadly until they just stop altogether. Then you can manually pick them up.

In short, don't use bots in Companions. Just put in 4 roboports until you need to go fight, then put in a laser and shield (in each Companion). I'm using 10 companions and it's a nice little fleet.

I had dreams of 100 Companions with 6 bots each using no inventory space in my character; oh well. Guess I'll have to be satisfied with a fleet of 100 laser fiends!

You shouldn't put construction robots in the companions

You shouldn't put construction robots in the companions

But... If I really really wanted to? What coding adjustments could be made to do that?