descend-stairs

name	descend-stairs
description	Walks down stairs via a sequence that steps a foot out and lowers the body down and forward (root.y drops, root.z advances). Use when a command mentions descend stairs, go downstairs, walk down the steps, head down a staircase, or take the stairs down.
category	locomotion
disable-model-invocation	true
subskills	["walk","move-leg"]

descend-stairs

Go down a staircase — each step extends a foot to the lower stair and lowers the body. A sequence whose root.y DECREASES while root.z advances.

How

• Use a sequence with loop:false (frame root is ABSOLUTE — y drops, z grows; compute forward from state.position+state.faceDeg, here origin facing +Z).
• Each step: reach a foot down and forward (UpLeg:[40,0,0],Leg:[30,0,0]), then settle onto it (legs to rest) as root.y lowers. Alternate legs.
• durationMs ~2400–2800.

Example

• "go down the stairs" (at x:0,z:0,faceDeg:0) -> {"durationMs":2600,"say":"Down we go.","sequence":{"loop":false,"frames":[{"t":0,"pose":{"LeftUpLeg":[40,0,0],"LeftLeg":[30,0,0],"RightUpLeg":[0,0,180],"RightLeg":[0,0,0]},"root":{"y":0,"z":0}},{"t":0.33,"pose":{"LeftUpLeg":[0,0,180],"LeftLeg":[0,0,0]},"root":{"y":-0.18,"z":0.3}},{"t":0.66,"pose":{"RightUpLeg":[40,0,0],"RightLeg":[30,0,0]},"root":{"y":-0.18,"z":0.5}},{"t":1,"pose":{"RightUpLeg":[0,0,180],"RightLeg":[0,0,0]},"root":{"y":-0.36,"z":0.8}}]}}