This will help to solve the problem of identifying messages that were already sent and stored in the server to avoid duplicating (or missing) messages.

In the Moodle app offline scenarios, this is particularly an issue when synchronising messages that were supposedly sent when the user was offline

Our proposal would be the following:

• For each message generated in a messaging client (the app or the LMS javascript client) create a unique id that is stored locally in the client
• The message unique id will be also stored in the server when the message is successfully saved in the system DB
• Thanks to these uniqueids the Messages API the server-side will be able to discard duplicated messages sent by a client.
• The client will use these uniqueids to also discard pending messages to be sent that are already stored in the server.