After adding an operation (mutation or query) to exchange the corresponding operation has to be added to Metaphysics. Because most of the clients don't use exchange directly since exchange doesn't know anything about galleries, users or artworks and it only keeps the ID of those entities. MP pulls that data from gravity and adds that to the order object coming from exchange.
This is a temporary solution for now. Graphql has a mechanism called sticking that can infer all these from the schema and defined types. At this point stitching is not fully implemented so it needs to be done manually. If you know that stitching is enabled for exchange stop reading and delete this document immediately.
Follow this PR as a reference: artsy/metaphysics#1375
- Copy updated exchange schema which includes the new mutation here: src/data/exchange.graphql (from exchange/_schema.graphql)