theory
equilibrium
velocity and the long-run split of idle and active supply
demurrage applies a constant pressure toward circulation. holding has a known cost per epoch, so a rational holder either accepts the bleed or becomes active to claim it back. in aggregate this raises velocity until the marginal benefit of moving equals the cost of moving.
the long run split of idle and active supply is not fixed by decree, it is found by behaviour. as more supply becomes active, each active wallet's share of the pool falls, which weakens the incentive to be active at the margin. as more supply sits idle, the pool grows relative to the active set, which strengthens it. the system settles where these two forces balance.
the renounced rate means this equilibrium is stable in its rules even as it moves in its numbers. participants can reason about the cost of holding without fearing a change in the contract beneath them.