Knockback body

Pairs with knockback-launch: launch owns the intended trajectory parameters; this skill owns collision-safe body motion.

Use the gameplay collision proxy published for the actor. If knockback uses a different proxy from locomotion, declare why and test the transition; do not silently switch shapes because a costume is larger.

Collision response

Sweep/continuous-test the displacement required by the target physics system rather than teleporting through geometry. Publish wall response as one of:

splat-state is a reaction state, not a reference to a nonexistent skill. Its stun/recovery timing is owned by hitstun-recover.

Floor contact publishes the landing event consumed by landing-lag. Slopes, moving surfaces and corners need the same collision evidence as flat floor.