Is my understanding correct in that a "Pane" is essentially a UI component? And I am assuming there are tests to catch cases where a new pane is defined in the backend, but not in the SDK (or I suppose, how do you deal with any discrepancy)? Do you lazy-load the components?
> Is my understanding correct in that a "Pane" is essentially a UI component?
Yes — it is essentially a UI component (and the only node that represents UI).
> And I am assuming there are tests to catch cases where a new pane is defined in the backend, but not in the SDK (or I suppose, how do you deal with any discrepancy)?
Great question! Because we use proto, the SDK and the backend share the same pane definitions. So we can't have a case where they don't match in the repo. However, SDKs that have already shipped obviously can't be updated with new panes. To handle this, we have a piece of the backend service called the "dispatcher" whose job it is to look at the initial /start request and determine which workflow should be used for that specific client.
Let's say a very old Android SDK is issuing a /start request. The dispatcher knows the version of the SDK requesting a workflow and programmatically can determine which major version of workflow graphs it supports, and pick an appropriate (older) workflow to send back where we know all panes are supported by the SDK.
We also have an escape hatch where the backend can tell an older SDK "actually, you're so old you should fallback on a webview implementation to get the latest and greatest experience".
