Message identifier for deduplication.

[ndr-brt]

In the current version, there's no messageId attributed in the messages.

Such property could be used to accomplish message deduplication: if for any reason, as timeout retry, a participant agent is sending a message multiple times, the counter party should be able to ignore another message that has been already processed or it's still in processing.

What's the group take on this?

[arnoweiss]

Profiles can further restrict DSP. That means adding more mandatory fields would be possible outside the core spec without a problem - within it would be breaking. I'd suggest to add a profile that adds @id to all message schemas and leave the json-ld context as-is.