Roland Johansen
Deity
At any rate, here's my postulization: As I think about it, I clearly notice this behavior occuring in a very specific situation, and there is no doubt that it is happening. When I have a unit on sea patrol (guarding a sea resource) and an attack sub comes to pillage that resource, a game mechanism prevents the attacking sub from actually pillaging that resource and instead initiates a battle between that foraging sub and my "on-call" defensive naval unit. Of course, for this exploit, the attacking sub loses and withdraws, and still possesses movement points. It then immediately attempts to pillage that very same resource again (or another next to it) and the game mechanism again takes over to prevent the pillaging and re-initiates combat. Hence, a second combat. Now, in this scenario, it should be clearly understood that the attack sub is not directly attacking my defensive naval unit but is instead attempting to pillage a resource that my naval unit is "on patrol" to protect; it is the multiple attempts at pillaging the same resource that initiates what appears to be multiple instances of attack, withdraw, attack, withdraw, attack...
Understand me?
(I've been silently following this thread.)
I think this could theoretically be bug-like behaviour in the game. I've never encountered it, but that doesn't mean it doesn't exist. The patrol function is clearly less tested than normal attack routines. It could induce bug-like behaviour.
I don't it is an AI exploit. From what I understand, it is the patrol function that allows ships to repeatedly initiate combat with hostile enemy units which try to pillage stuff close to the unit(s) on patrol duty. When AI units are on patrol protecting AI resources, then I see no reason why human units couldn't try to repeatedly pillage these AI resources and this would allow these units to repeatedly initiate combat.
It's a bit hard to find a perfect solution for this weird behaviour of the patrol function. You can't stop the patrol function from initiating repeated combat because that would stop the function from doing what it says it does: protect the resources. I also wouldn't be in favour of removing the ability of multiple move units to pillage more than once or to attack and pillage. It is one of the great advantages of fast units and it would especially hurt the fast land units. They wouldn't be able to move in a large stack and pillage or attack and pillage. You could change the patrol unit into the attacker and thereby deny the pillager the possibility to retreat but that would give the pillager the defencive terrain bonus of coastal terrain which I personally think is a bad idea. The advantage should be towards the defender.
If this bug-like behaviour really exists, then I would disallow a unit who is in combat with a patrol unit the possibility to retreat. It's a special case rule, but in my opinion the best way to solve the strange bug-like behaviour.
But first things first. We need a controlled environment test that can show whether this issue with the patrol function really exists. I don't have the time to do that now so I hope Psyringe has the time and willingness to set up a world builder scenario again. Luckily, it's much easier to prove a bug than to disprove it. You just need one repeatable instance of the bug to prove its existence.