Inspired by the problem of biofilm growth, we numerically investigate
clustering in a two-dimensional suspension of active (Janus) particles of
finite size confined in a circular cavity. Their dynamics is regulated by a
non-reciprocal mechanism that causes them to switch from active to passive
above a certain threshold of the perceived near-neighbor density (quorum
sensing).A variety of cluster phases -- glassy, solid (hexatic) and liquid --
is observed depending on the particle dynamics at the boundary, the quorum
sensing range, and the level of nois