ChatMessage & co. JSON serialization stability

[FICTURE7]

Are there any guarantees around the JSON serialization stability of ChatMessage & co, i.e is it safe to serialize it to JSON and not be worried about compatibility breaking in a future update of MEAI?

In MAF, the Cosmos ChatHistoryProvider implementation seem to make that assumption: https://github.com/microsoft/agent-framework/blob/1ca43f96432bd1fcb85542e112f6c5578035b831/dotnet/src/Microsoft.Agents.AI.CosmosNoSql/CosmosChatHistoryProvider.cs#L255

But the DurableTask implementation on the other hand, go the extra mile to decouple its serialization from these core types: https://github.com/microsoft/agent-framework/tree/main/dotnet/src/Microsoft.Agents.AI.DurableTask/State#state-schema

What is the recommendation for persisting these types? Apologies if this has been answered before.

[stephentoub]

We are certainly trying to avoid breaking serialization via changed format; doing so would be problematic for all the places like the one you cite, where serialized forms of the messages are persisted and need to be roundtrippable.

[FICTURE7]

Fair enough. I take it that the DurableTask approach to mirror the types might not have been entirely necessary.