Reliable FastAPI Realtime Access with Short-Lived Tokens for Marketplace Boards

Short answer: use short-lived access tokens, but choose the realtime surface by how explicitly it exposes authentication, subscription state, and business events during reconnects; for a marketplace whiteboard that pushes in-app notifications without polling, presence accuracy and deterministic reconciliation matter more than a long feature list. An expired token isn't the same thing as an absent editor. A marketplace operator can still have the board open while a credential is being refreshed, and a dropped transport can make a connected user look present after the user has gone. Treating tho