  We analyze the presence of non-reciprocal critical currents, the so-called
superconducting diode effect, in chiral superconductors within a generalized
Ginzburg-Landau framework. After deriving its key symmetry conditions we
illustrate the basic mechanism for two examples, the critical current in a thin
film and a Josephson junction. The appearance of spontaneous edge currents and
the energy bias for the formation of Josephson vortices play an essential part
in establishing a splitting of the critical currents running in opposite
directions. Eventually, this allows us to interpret a superconducting diode
effect observed in the 3-Kelvin phase of Sr$_2$RuO$_4$ as evidence for
spontaneously broken time-reversal symmetry in the superconducting phase.
