My understanding about GOAP is that the planner will perform a regressive search on the action space for a valid sequence of actions that will take the NPC from some starting state to the goal state. In each step of the regressive search, the planner tries to identify a valid action that has an effect that can resolve one of the unsatisfied goal conditions. Every time an action is added to the planner, the goal state grows as well because the precondition of the appended action will be added as another goal condition. Here’s some context: