ROOM_NOT_FOUND
The server could not find an active room instance for the requested realm/room id.
Classification
Application code. The wire value and spelling remain the same in every language. A registered code does not establish that its feature is active in every deployment.
Handling
Use the operation context and authoritative state to choose recovery. Correct rejected input or permissions first. Do not assign a universal HTTP status, disconnect policy or automatic retry rule from this code alone. Record the code and trace ID; keep raw diagnostics private.