The client passed a User-Agent-derived string as a WebSocket subprotocol for attribution, but Spacedust doesn't negotiate one. When a client requests a subprotocol the server doesn't echo back, the handshake fails ('Server sent no subprotocol') - which is why every live-notifications connection dropped. Verified live: connecting with no subprotocol opens fine; with the subprotocol it errors. Removed it - real-time like/repost/reply/follow notifications now connect.