Realtime rooms now keep 10,000 messages
Reconnect after a train tunnel and the room is still there, in order.
Rooms used to remember their last 500 messages. That was enough for a quick reconnect after a dropped signal, but not for a lunch break, a long meeting or a train tunnel on the way home. People came back to a room with a gap in the middle of the conversation.
Every room now keeps its last 10,000 messages, stored next to the room in its primary region. When a client reconnects it sends the id of the last message it saw, and the room replies with everything after it, in order, before live messages start again. Nobody has to reload the page or scroll for missing context.
History works the same for chat, cursors and live dashboards. A dashboard that was closed overnight can replay the last few thousand updates and draw the morning without a separate query to your database.
Nothing to change in your code. History is on for every room today. If a channel should forget sooner, for privacy or for noise, lower the limit for that channel in one line of your room rules. Older messages beyond the limit are dropped in order, oldest first, and never sent to a client again.
History is counted as storage at the normal rate, and a busy room of 10,000 short messages takes about two megabytes, so for most teams the change costs nothing they will see on an invoice.