Offer curves in general equilibrium
In the picture below offer curve of individual 1 is given by lines connecting $E$ to $O_1$ and $O_1$ to $O_2$. And offer curve of individual 2 is given by lines connecting $E$ to $O_2$ and $O_2$ to $A$ and $A$ to $O_1$. Set of competitive equilibria are given by the intersection of two offer curves.
$p_X = 0$ and $p_Y = 1$ supports allocation at $O_2$ as competitive equilibrium. Allocations on the line segment $O_1A$ are supported by prices $p_X = 1$ and $p_Y = 0$.