Hey, this isn’t a bug, it’s the default behavior. Cursor keeps up to 5 chat tabs open by default, and when you create a new one at the limit, the oldest inactive tab closes automatically.
Your chats aren’t lost, you can restore them from history in the Agents sidebar.
Fix: increase the limit in Cursor Settings > Agents > Max Tab Count. You can pick 10, Unlimited, or set a custom value.
Also, if you turn on Open chat as editor tabs in Cursor Settings > General > Layout, the tabs are more likely to persist after restart.
More details with steps and screenshots: Chat tabs dissapearing - #5 by Colin