Background

The OpenTelemetry semantic conventions PR open-telemetry/semantic-conventions#3249 (merged) adds a new invoke_workflow operation name to the GenAI semantic conventions. This represents a coordinated process composed of multiple agents or other operations involving generative AI — essentially a parent grouping span similar to invoke_agent.

Problem

Currently, FunctionInvokingChatClient has special behavior when it detects it is running inside an invoke_agent span:

1. Suppresses the orchestrate_tools span — since invoke_agent already serves as a grouping span
2. Reuses the agent's ActivitySource — so that child execute_tool spans are properly parented
3. Propagates EnableSensitiveData — reads the custom property from the agent activity

The invoke_workflow span serves the same parent-grouping role, so FunctionInvokingChatClient should treat it identically.

Required Changes

1. src/Libraries/Microsoft.Extensions.AI/OpenTelemetryConsts.cs

Add a new constant after InvokeAgentName:

public const string InvokeWorkflowName = "invoke_workflow";

2. src/Libraries/Microsoft.Extensions.AI/ChatCompletion/FunctionInvokingChatClient.cs

Update CurrentActivityIsInvokeAgent to also match invoke_workflow parent spans. The property currently checks if Activity.Current.DisplayName starts with "invoke_agent" followed by end-of-string or a space. It should be generalized to also match "invoke_workflow" the same way. The cleanest approach:

• Extract a helper method static bool IsActivityDisplayNameMatch(string? displayName, string operationName) that does the StartsWith + boundary check
• Update CurrentActivityIsInvokeAgent to check both InvokeAgentName and InvokeWorkflowName using the helper (or rename the property to reflect both)
• Update the XML doc comment and code comments referencing "invoke_agent" to also mention "invoke_workflow"

This affects these call sites (no changes needed at call sites if the property itself is updated):

• GetResponseAsync: using Activity? activity = CurrentActivityIsInvokeAgent ? null : _activitySource?.StartActivity(...)
• GetStreamingResponseAsync: same pattern
• InstrumentedInvokeFunctionAsync: Activity? invokeAgentActivity = CurrentActivityIsInvokeAgent ? Activity.Current : null;

3. test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/FunctionInvokingChatClientTests.cs

Add test cases mirroring existing invoke_agent tests:

• DoesNotCreateOrchestrateToolsSpanWhenInvokeWorkflowIsParent — with [InlineData("invoke_workflow")], [InlineData("invoke_workflow my_workflow")], [InlineData("invoke_workflow ")]
• StreamingPreservesTraceContextWhenInvokeWorkflowWithNameIsParent
• UsesWorkflowActivitySourceWhenInvokeWorkflowIsParent
• SensitiveDataPropagatesFromWorkflowActivityWhenInvokeWorkflowIsParent
• Update CreatesOrchestrateToolsSpanWhenParentIsNotInvokeAgent to also test invoke_workflow-like non-matches: "invoke_workflo", "invoke_workflow_extra", "invoke_workflowx"

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Anything we need to do to support @open-telemetry/semantic-conventions/pull/3249 in Microsoft.Extensions.AI?

Assistant:

Let me investigate the PR and the current codebase to understand what changes might be needed.

Assistant: Now let me look more closely at the key files to understand how invoke_agent is currently handled and whether invoke_workflow needs similar support:

Assistant: Now let me also check how the CurrentActivityIsInvokeAgent property is used more broadly in the orchestrate_tools span creation logic:

Assistant: Now let me also check how the non-streaming path uses this same pattern:

Assistant: Now let me also check the non-streaming GetResponseAsync for the same pattern:

Assistant: Now let me also check the non-streaming path for the orchestrate_tools span:

Assistant: Now let me find the specific usage in GetResponseAsync (non-streaming) too:

Assistant: Now I have a comprehensive understanding of the situation. Let me summarize my findings.

Analysis: Impact of open-telemetry/semantic-conventions#3249 on Microsoft.Extensions.AI

The merged PR adds two things to the OpenTelemetry GenAI semantic conventions:

1. A new invoke_workflow operation name — a new well-known value for gen_ai.operation.name
2. A new gen_ai.workflow.name attribute — a human-readable name for the workflow

What currently exists in dotnet/extensions

There are two key areas in Microsoft.Extensions.AI that interact with the invoke_agent operation name and would need to be aware of invoke_workflow:

1. OpenTelemetryConsts.GenAI (OpenTelemetryConsts.cs)

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