  A minimal model for self-organized critical percolation on directed graphs
with activating and de-activating links is studied. Unlike classical
self-organized criticality, the variables that determine criticality are
separated from the dynamical variables of the system and evolve on a slower
timescale, resulting in robust criticality. While activity of nodes percolates
across the network, the network self-organizes through local adjustment of
links according to the criterion that a link's adjacent nodes' average
activities become similar. As a result, the network self-organizes to the
percolation transition with activity avalanches propagating marginally across
the graph. No fine-tuning of parameters is needed.
