[hWuxH]

> What if this is not about closing off an API. Maintaining a stable API is difficult

That's why any sane software uses a stable public API and an internal one that can be closed off or has breaking changes all the time.

> MQTT has no versioning and limited hierarchy in the pub / sub model

It's currently handled like this: https://github.com/Doridian/OpenBambuAPI/blob/main/mqtt.md. Would it be a far stretch to add an "api_version":x field and a "internal_" prefix for some commands?