gaerzi wrote: So the trick is to send your colony ship with your armada, so that you claim the system in the same turn as the one you liberated it.

Noted.

I don't think so. They'd need to have the same technology. And you can't trade technology.

Okay, so I don't have to be paranoid about giving away access to places.

Thank you. Much obliged.
If all else fails, there's always 'undo'. Which is an amazing feature in a game like this.

gaerzi wrote: You can even get in a funny situation. Something that happened to me.
Turn X: I liberate a space harpy system
Turn X+2: my colony ship arrives. The Ashdar Colonials protest. I comply and get the diplomatic bonus for letting them expand in my territory.
Turn X+7: their colony ship arrives. I intercept it. Since they like me, they comply.
Turn X+22: my agreement not to settle the system expires. I settle, to nobody's objection.

I've noticed similar behaviors as well, and consider them a bit of a bug. The biggest problem, in my mind, is that if you intercept an AI colony ship, there's a chance that the AI will comply with your request to leave the system, and there will be no rep penalty. But if they notice your colony ship in a system they want, they'll generally make a big stink about it, and there's always a rep penalty. That creates perverse incentives for people who have figured out how all the events work.

As of r38664, I think these events should be better balanced. Using military ships to prevent an AI colony will now always carry a small rep penalty, and that rep penalty will be equal to rep penalty that you get if you colonize a system the AI wants. Also, the AI will no longer be "gravely offended" if you take a system they had their eye on (though the bonus for leaving it for them is still quite high).