unreadMessages

unreadMessages is a term used in messaging applications to refer to the set of messages that have not yet been read by a user. Depending on implementation, unreadMessages may be stored as an integer counter representing the total number of unread messages for a user across conversations, or as a per-conversation collection of message identifiers that are unread.

In practice, unreadMessages is used to display badges, drive notification prompts, and optimize data loading by focusing on unread content. Server-side implementations often maintain a per-user per-conversation unreadCount and may expose a sum total for the user. Client-side code may cache this value and update it in response to incoming messages or user actions.

Updating rules: when a new message arrives in a conversation and the user has not opened it, the unread count increases. When the user opens or marks that conversation as read, the unread flags are cleared for those messages, and the counter is decreased. Some systems support marking messages as read individually or in bulk. In multi-device setups, synchronization mechanisms ensure the unread state is consistent across devices, typically using server-side state and push notifications.

Edge cases include messages that are deleted or expired while unread, or conversations with muted notifications where unread is still tracked but notification delivery differs. Localization requires language-specific pluralization for displays like "1 unread message" vs "2 unread messages".

Security and privacy considerations include exposing unread counts in analytics or UI, and ensuring that unread state is not exposed beyond the intended scope.