.NET: introduce API to manage the thread in Hosting scenarios #1392
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Pull Request Overview
This PR introduces an API for managing agent threads in hosting scenarios, enabling persistent storage and retrieval of conversation threads across HTTP requests and application restarts.
- Introduces the
IAgentThreadStoreinterface for persistent thread storage - Provides
NoContextAgentThreadStore(no-op) andInMemoryAgentThreadStoreimplementations - Adds
AIHostAgentwrapper that combines agents with thread persistence capabilities
Reviewed Changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| IAgentThreadStore.cs | Defines the interface contract for thread storage operations |
| NoContextAgentThreadStore.cs | Provides a no-op implementation that returns null threads |
| InMemoryAgentThreadStore.cs | Implements in-memory thread storage using ConcurrentDictionary |
| AIHostAgent.cs | Wraps AIAgent with thread persistence capabilities |
| HostAgentBuilderExtensions.cs | Extension methods for configuring thread stores with agents |
| AIAgentExtensions.cs | Updates A2A messaging to support thread persistence |
| WebApplicationExtensions.cs | Updates ASP.NET Core integration to use thread stores |
| Program.cs | Sample showing in-memory thread store configuration |
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| public ValueTask<JsonElement?> GetOrCreateThreadAsync(string conversationId, string agentId, CancellationToken cancellationToken = default) | ||
| { | ||
| // this is OK, Agents should be prepared to handle null threads. | ||
| return new ValueTask<JsonElement?>(result: null!); |
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The null-forgiving operator ! is unnecessary here since null is already being explicitly passed. This should be return new ValueTask<JsonElement?>(result: null);
| return new ValueTask<JsonElement?>(result: null!); | |
| return new ValueTask<JsonElement?>(result: null); |
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| CancellationToken cancellationToken = default) | ||
| { | ||
| var key = GetKey(conversationId, agentId); | ||
| var threadContent = this._threads.GetOrAdd(key, value: JsonDocument.Parse("{}").RootElement); |
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Creating a new JsonDocument on every call to GetOrAdd is inefficient. Consider creating a static readonly instance of the empty JSON element to reuse across all calls.
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| var contextId = messageSendParams.Message.ContextId ?? Guid.NewGuid().ToString("N"); | ||
| var parts = response.Messages.ToParts(); | ||
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| await hostAgent.SaveThreadAsync(contextId, thread!, cancellationToken).ConfigureAwait(false); |
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The null-forgiving operator ! is used on thread but thread can be null from RestoreThreadAsync. This could cause a NullReferenceException. Check if thread is null before saving or handle the null case appropriately.
| await hostAgent.SaveThreadAsync(contextId, thread!, cancellationToken).ConfigureAwait(false); | |
| if (thread == null) | |
| { | |
| throw new InvalidOperationException("Failed to restore thread: thread is null."); | |
| } | |
| await hostAgent.SaveThreadAsync(contextId, thread, cancellationToken).ConfigureAwait(false); |
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2 participants
[heavy wip]