This is seriously impressive work - thank you for building MassDroid. I really like the direction here: room detection and transfer logic inside the app, without forcing people to build huge Home Assistant automation stacks around presence helpers, template sensors, and room entities just to make multiroom playback feel natural.
On the Sendspin Bluetooth Bridge side, we’ve just added a few things specifically to make this kind of Follow Me workflow easier with Bluetooth speakers, especially for people running our Home
Assistant add-on. Bridge-backed speakers can now carry stable per-device room metadata (room_id / room_name), with Home Assistant area fallback available in add-on mode, so room mapping is much easier to keep consistent. We also added a derived transfer_readiness state to show whether a speaker is actually ready for handoff, plus an optional fast_handoff mode that keeps selected speakers warmer for quicker transfers.
We’re also surfacing that room/readiness context in the bridge UI and in event/webhook payloads, so HA users can still layer automations on top if they want, but they no longer have to depend on them for the basic room-following flow.
So rather than trying to invent a direct bridge-to-app protocol, we focused on making Bluetooth speakers exposed through our bridge behave like better Music Assistant room endpoints for MassDroid to target. Really excited to see where you take Follow Me next.