We have a graphql server not written in javascript, which we're trying to conform to the relay specification. startCursor and endCursor show up in a few examples but not in any official docs; based on my reading of https://github.com/facebook/relay/issues/372 those fields are basically deprecated, but they do show up in some code still. Do we have to implement them:
No, they're not deprecated, and they do show up in the docs. What that issue says is that you don't have to implement them if you don't want to use them directly in your app, because Relay is going to query the cursor for each edge in a connection automatically, and will use that when making requests during pagination.