Blackboard (AI)
A shared memory that different AI components read from and write to in order to coordinate, instead of calling each other directly.
The pattern comes from 1970s expert systems — Hearsay-II for speech recognition was the first — where independent modules ("knowledge sources") posted partial results on a common "blackboard" that others could build on. In games the board is a key-value store that decouples sensing, decision and action: one module writes "enemy seen here", another reads it later.
Pairing it with behavior trees is now standard — Unreal's AI is built explicitly around a Blackboard asset that the trees read and write. The board is also the natural place for squad AI to share state, so a whole team can coordinate a flank without every agent talking to every other.