Agency is often mistaken for behaviour. In APS, however, behaviour is only one possible expression of agency.
Agency refers to the viability-oriented activity through which living systems sustain the conditions of their own continued persistence. Behaviour may contribute to this activity, but many forms of biological agency occur without overt behaviour.
Cells regulate metabolism, tissues repair damage, organisms maintain physiological stability, and developmental systems coordinate transformation without necessarily producing the kinds of observable actions normally associated with behaviour.
For this reason, APS treats behaviour as one manifestation of agency rather than its defining feature. Agency concerns the organisation of viability-oriented activity; behaviour is one of the ways that activity may be expressed.
APS Principle: Behaviour may reveal agency, but agency is broader than behaviour because viability-oriented organisation extends far beyond observable action.