[Cipher7071]

Thanks guys. The boarding parties are placed ahead of the DUCs in the ship design. So that leaves ramming.

Given that, I think I know what happened. My boarding ship had been given orders to capture the colony ship. It had also been given orders to resupply. So, it tried to capture the colony ship, was rammed, and the colony ship was destroyed. It did take damage, but neither that nor the ram was apparent in the combat replay. In the same turn it flew to the nearest planet with a resupply depot, AND a spaceyard. It was repaired.