I was thinking at work and this scenario popped in my head and I am very curious that is could very well cause an infinite combat cycle.
Ok, let's say it's later in the game I have created a custom class of constructor ship. It has no attack, but has 10 shield defense against beam weapons. Now let's say that I go to war with a civ that is still using the crappy core designs that only do 1 beam damage. Now if my constructor ship is attacked by this weak little fighter, from what I understand of the combat mechanics, my shields would deflect every shot but then since my constructor ship has no attack to return fire, would this cause an infinite combat cycle?