The SDK version numbers aren’t something we treat as public, and the SDK’s changelog is written with SDK developers–not end users–in mind. There is no defined relationship between SDK versions and Roon Bridge versions.
Most SDK releases are motivated by a new device that’s in development or in the certification process. New capabilities are almost always specific to some new device, disabled by default, and are enabled either by a future Roon release, or when the manufacturer turns that capability on in their firmware, or both.
For example, 1.1.13: It adds a new capability that applies to one, not-yet-released Roon Ready device only when it’s used in conjunction with Roon 1.3. The need for this capability is unique to this one product, and other Roon Ready devices would not benefit from it. The developers at that company needed an SDK update so they could get started writing the code to hook up their end of things. There isn’t much for us to say to announce in public about something like that. When that product comes out it will “just work”. That’s the point of Roon Ready.
When we do a major upgrade like a theoretical “RAAT 2.0” that enables new features or makes some big sweeping improvements, we’ll announce details and explain it to everyone. But most of the SDK release traffic looks more like what I described above.
Small Green Computer is in the minority pushing each SDK release out to their customers rapidly–most manufacturers do not. This has positives and negatives. SGC is always “up to date” with whatever we’ve done, at the expense of pushing some updates that have no real effect on their products. This is a valid choice–they have a very nice software update system compared to a lot of products, so this is easy for them to push updates rapidly and fix things quickly were something to go wrong.
I hope this cleared things up. If you have any other questions/feedback, please let us know.