Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for robotics planning. One of the methods comprises receiving data defining multiple skills to be performed by one or more robots in an operating environment; invoking a projection function implemented by a skill, wherein the projection function generates a skill footprint representing resources requested for performing the skill and a volume occupied by a corresponding entity used to perform the skill; determining that an initial skill footprint generated by the projection function conflicts with a skill footprint of another skill already being executed; and in response, reinvoking the projection function with data representing the skill footprint of the other skill already being executed.