Unless I missed anything, this means that the server-to-server communication only relies on sequence numbers, and is not even aware of timestamps. So optional or removed timestamps will not directly effect the non-implementation-specific rpcs. That's pretty great.

TODO: At some point, #somebodyshould clearly document the boundary between server-to-server and server-to-client communication. This is exactly what implementors need to know to get a minimum viable pub working.

@mix:

we don't find a performant way to do causal queries, which <opinion>forces use to defer removing timstamps / branch</opinion>

I tentatively agree with that opinion. But what about making timestamps optional? How would you feel about optional timestamps without support for causal queries (yet)? Because it looks like the whole database reachability thing will be difficult enough to push into a later update.