Reporting versioning-related errors

[michielbdejong]

Section 3.5 says:

If a server has dropped the history that a client requests, the
server can return a 410 GONE response, to tell the client "sorry, I
don't have the history necessary to synchronize with you."

But if the server really dropped the history, then how would it know if the parent 1234567 a client is referring to is really 'gone' or maybe this version ID never was a part of this DAG to begin with?

I think the idea of Braid is that updates and merges never fail, right? So the merge algorithm should guarantee this? That does make it a lot easier than git push, which might for instance result in 'push rejected, please pull and rebase and try again'.

But even then, I could think of a number of useful versioning-related error codes, such as 'version not found', 'parent not found', 'merge algorithm not supported', 'merge failed'.