Custom credentials can be configured through synchronously providing credential schemas in Fetch Store Credentials (stores.fetch_credentials) webhook.
When custom credentials are configured, their values will be present in the Upsert Store (stores.upsert) webhook.
When a store is added on Public API internal services, the stores.upsert webhook is called and partner must return 2XX if accepted.
In the manual scenario, the webhook can be used to signal in the partner systems that a store is waiting for manual onboarding. The store in this state will be available in Developer Portal for manually finish onboarding by providing the external store id.
