According to https://www.routesonline.com/news/38...from-may-2018/, CX will add its code on AS's flights between SFO and LAS, MSY, RDU, SLC, SAN, and IAD. I believe most of these routes are currently operated by VX and will become AS in a month, so CX will commence the code-share afterwards.

Ex-Taiwan, currently CX*/AS flights cannot be used for Intra-North America add-on fares. Only CX*/AA and AA flights are eligible. Hope they will allow CX*/AS and AS flights in the future, too.