the spec covers more than just the client/server API. the server/server API covers the basis of how data is replicated, and conflict resolution is defined on a

the spec covers more than just the client/server API. the server/server API covers the basis of how data is replicated, and conflict resolution is defined on a per room version as per https://matrix.org/docs/spec/rooms/v2 https://matrix.org/docs/spec/rooms/v2. there are then guides like https://matrix.org/docs/guides/implementing-stateres https://matrix.org/docs/guides/implementing-stateres which help expand on that and other areas to make it easier to conceptualise.