.NET: [Issue]: .NET: AdditionalProperties saved to ChatResponseUpdate not stored in message store

[stekiri]

Language

.NET

Type of Issue

Bug

Microsoft.Agents.AI

dotnet-1.0.0-preview.251219.1

Microsoft.Agents.AI.Abstractions

No response

Microsoft.Agents.AI.OpenAI

No response

Microsoft.Agents.AI.AzureAI

No response

Microsoft.Agents.AI.Anthropic

No response

Microsoft.Agents.AI.Hosting

No response

Microsoft.Agents.AI.Workflows

No response

Other .NET Packages

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agent-framework-core

No response

agent-framework-azure-ai

No response

agent-framework-anthropic

No response

agent-framework-azurefunctions

No response

Other Python Packages

No response

Description

In non-streaming mode: When adding AdditionalProperties to the ChatResponse in the GetResponseAsync method of a IChatClient implementation, the AdditionalProperties are stored correctly in a message store.

In streaming mode: When adding AdditionalProperties to a ChatResponseUpdate in the GetStreamingResponseAsync method of a IChatClient implementation, the AdditionalProperties are not stored in the message store.

The reason is as follows:

1. The list of ChatResponseUpdates gets converted to a ChatResponse object (https://github.com/microsoft/agent-framework/blob/dotnet-1.0.0-preview.251219.1/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs#L268).
2. However, the conversion method only adds the AdditionalProperties to the ChatResponse and not the underlying list of ChatMessage objects (https://github.com/dotnet/extensions/blob/v10.0.0/src/Libraries/Microsoft.Extensions.AI.Abstractions/ChatCompletion/ChatResponseExtensions.cs#L581-L591).
3. Then, these chat messages without the additional properties are sent to the message store (https://github.com/microsoft/agent-framework/blob/dotnet-1.0.0-preview.251219.1/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs#L275).

I wasn't entirely sure if I should create an issue directly in Microsoft.Extensions.AI.Abstractions, I wanted to at least leave a trace here to justify the need.

Let me know how to proceed.

Code Sample

Additional Context

No response