Failed to Coalesce Web Search Tool Call Content

[c-t-fallon]

Description

Getting an exception on my await for each loop using the AIAgent .RunStreamingAsync() method. Occurs after the web search tool completes. But it does seem like maybe this operation isnt thread safe? Difficult to know exactly because I'm struggling to reproduce, I might have something wrong in my main application as well.

System.InvalidOperationException
HResult=0x80131509
Message=Collection was modified; enumeration operation may not execute.
Source=System.Private.CoreLib
StackTrace:
at System.ThrowHelper.ThrowInvalidOperationException_InvalidOperation_EnumFailedVersion()
at System.Collections.Generic.List1.Enumerator.MoveNext() at Microsoft.Extensions.AI.ChatResponseExtensions.CoalesceWebSearchToolCallContent(IList1 contents)
at Microsoft.Extensions.AI.ChatResponseExtensions.CoalesceContent(IList1 contents) at Microsoft.Extensions.AI.ChatResponseExtensions.FinalizeResponse(ChatResponse response) at Microsoft.Extensions.AI.ChatResponseExtensions.ToChatResponse(IEnumerable1 updates)
at Microsoft.Agents.AI.ChatClientAgent.d__29.MoveNext()
at Microsoft.Agents.AI.ChatClientAgent.d__29.System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult(Int16 token)
at Microsoft.Agents.AI.AIAgent.d__33.MoveNext()
at Microsoft.Agents.AI.AIAgent.d__33.MoveNext()
at Microsoft.Agents.AI.AIAgent.d__33.System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult(Int16 token)
at IMEG_Euclid.Agent.AI.Sessions.AgentSession.d__5.MoveNext() in D:\repos\IMEG_Euclid\IMEG_Euclid.Agent\AI\Sessions\AgentSession.cs:line 52

This exception was originally thrown at this call stack:
[External Code]
IMEG_Euclid.Agent.AI.Sessions.AgentSession.RunStreamingAsync(System.Collections.Generic.IReadOnlyList<Microsoft.Extensions.AI.ChatMessage>, IMEG_Euclid.Agent.AI.AIInvocationOptions, System.Threading.CancellationToken) in AgentSession.cs

Reproduction Steps

Unable to reproduce on smaller scale application.

Expected behavior

No exception.

Actual behavior

Exception.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

[c-t-fallon]

If this helps - here is the state of the content collection when the exception hits

havent figured out yet why I'm getting this state

[stephentoub]

Thanks. I have a fix, just need to put it up.

[c-t-fallon]

Ah, thank you! Didn't mean to rush, I just got some time to investigate again.