Support versus substitution is how the framework tells healthy assistance from the slow hollowing of a participant. Support helps a person carry their own geometry; substitution carries it so completely that the capacity never develops or is gradually lost. The same tool can do either — the same navigation aid can teach someone a city or ensure they never learn it — so the distinction is not about the technology but about its effect on future capacity.
From it follows the design rule that, outside a genuine emergency, assistance should default toward capability transfer: repeated help should leave the participant more able to act without it, not less. This is the mechanism underneath competence-preserving dependency, and it is why the framework wants dependency kept visible — the difference between support and substitution is easy to miss from the inside, because a capacity someone has quietly stopped exercising still feels like one they possess.