Spartan R41:

The Covenant does have AI. Cortana encountered one, an unnamed AI on the ship Ascendant Justice. She was also able to destroy it. Plus, almost every single Covenant weapon and vehicle is derived from Forerunner tech. While it's preached that it's heresy to alter them, the Prophets did it at times. So what would stop them from making an AI?

Okay i missed that because i have not read first strike in a while

Spartan R41:

343 Guilty Spark was over 100,000 years old, giving him ample time to over-process information and "out think" himself. Spark was rampant. There was no such thing as a "Perfect" AI, and even Forerunner AI went rampant. Just look at Mendicant Bias.

There is such a thing as a perfect A.I. it is a sentient A.I. that has limits to how it learns, A.I.'s "die" because they gain information to fast and end up getting contradictory information that are both considered right and cannot possibly rationalize all this information OR gets it will start to think its better than its creators and does not need them to do its job. A perfect A.I. is purely programed un-like the Smart A.I.'s that must copy neural pathways, which is its greatest strength and weakness, they learn like Smart A.I.'s but can last forever like Dumb A.I.'s, they know that they are equal's with their creators and may have different responsibilities