How to Design Reconnect-Safe Stale User Cleanup for Online Classrooms — A Runbook

To create a reconnect-safe stale user cleanup for online classrooms, treat stale-user cleanup as a data contract and test key aspects before choosing a realtime service. Maintain a stable user identifier and monotonic session version to enable reconnects to restore state without reactivating learners who have left. Establish a shared contract with fields such as stable user_id, connection-specific session_id, version for state change tracking, and server-timestamped observed_at.

Define recovery behavior where clients resend their last applied version to obtain current events after that version. Duplicate events are expected and must be handled idempotently. Authorization should be included in the contract, allowing only authorized entities to modify room state. Choose a service like Infrai that offers a REST API with minimal dependencies and a unified set of routes and modules.

The contract should include only essential fields to minimize integration complexities. Test the realtime stale-user contract with a small experiment using synthetic users and various reconnect scenarios to ensure proper state convergence. Ensure the client ends with one row per stable user_id, older duplicates do not overwrite newer versions, expired sessions become offline within the declared window, reconnects receive either missing events or a complete snapshot, and unauthorized cleanup is rejected without modifying room state.

Capture request IDs and timestamps for debugging purposes. Use a minimal Go probe to discover available event types and handle rate limits securely before running tests.