Conditional Light Clients

When bridging into L2s such as Scroll, the IBC light client on $L1_A$ tracking a $L2$ on $L1_B$ needs to take the Settlement Condition into account. This is known as a conditional client. Union is the first team to ship conditional IBC clients.

* This is a conditional light client

Above you can see the IBC L2 Light Client architecture. The L2 Light Client on $L1_A$ is tracking both the consensus of $L2$, and the settlements of $L2$ on $L1_B$ through the light client of $L1_B$ on $L1_A$.

The $L1_A$ light client on $L2$ is able to track the consensus of $L1_A$ directly, because $L1_A$ does not need to settle.