What should a horse know before starting obstacle training?

Before obstacle training begins, the horse should have a functional foundation of basic responses that allow the handler to communicate clearly and safely when an obstacle presents a challenge. On the ground, the horse should lead quietly beside the handler without dragging or rushing, stop promptly from a light lead cue, back willingly in a straight line, yield the hindquarters away from pressure, move the shoulders away from light leg or hand pressure, stand quietly when asked without pawing or moving off, respect the handler's personal space consistently, and respond to light pressure with a yield rather than a brace or flight response. These foundational responses matter specifically for obstacle training because an obstacle that causes the horse anxiety will test each of those responses under mild pressure — a horse that does not yield the hindquarters on the ground will not yield it reliably when frightened by a tarp, and a horse that does not respect the handler's space will crowd or run over them when something startles it. Under saddle, the horse should steer softly left and right from a light rein, stop from a seat cue without requiring significant rein pressure, back willingly in a straight line, move forward willingly from a light leg without requiring strong driving, and maintain a reasonably calm and workable mental state in familiar environments. A horse without those foundational responses will encounter obstacles and have no tools available for the handler to use — every correction and every guidance attempt will be fought or confused. The foundational responses installed before obstacle work begins are the tools that make obstacle training progressive and safe rather than chaotic and dangerous.