.NET: BREAKING: Unify `AgentResponse[Update]` events as `WorkflowOutputEvent`s by lokitoth · Pull Request #3441 · microsoft/agent-framework

lokitoth · 2026-01-26T16:33:39Z

Motivation and Context

The streaming AgentResponseUpdate and full AgentResponse events were added before the WorkflowOutputEvent mechanism was formalized, leading to a pair of vestigial events that cause confusion for users.

Reconciling the two will make it clearer how to listen to Workflow outputs, though we special-case it to continue avoiding the output filtering logic, via WithOutputFrom().

Description

Python-parity: Breaking: Renames WorkflowOutputEvent.SourceId to WorkflowOutputEvent.ExecutorId
Adds [Obsolete] SourceId forwarding to ExecutorId on WorkflowOutputEvent
Changes AgentResponseUpdateEvent and AgentResponseEvent to derive from WorkflowOutputEvent to unify handling
Fixes .NET : Agents in Workflow. WorkflowOutputEvent not triggered #2938

BREAKING CHANGES:

Rename WorkflowOutputEvent.SourceId to WorkflowOutputEvent.ExecutorId

Contribution Checklist

The code builds clean without any errors or warnings
The PR follows the Contribution Guidelines
All unit tests pass, and I have added new tests where possible
Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

Copilot

Pull request overview

This PR unifies agent response events under the WorkflowOutputEvent hierarchy to address confusion about how to listen to workflow outputs from agents. The change makes AgentResponseUpdateEvent and AgentResponseEvent derive from WorkflowOutputEvent instead of ExecutorEvent, and renames WorkflowOutputEvent.SourceId to ExecutorId for Python parity.

Changes:

Renamed WorkflowOutputEvent.SourceId to ExecutorId with obsolete forwarding property for backward compatibility
Changed AgentResponseUpdateEvent and AgentResponseEvent to inherit from WorkflowOutputEvent instead of ExecutorEvent
Updated executors to use YieldOutputAsync() instead of directly calling AddEventAsync() for agent events, ensuring consistent special-case handling

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
`WorkflowOutputEvent.cs`	Changed class from sealed to non-sealed, renamed property `SourceId` to `ExecutorId` with obsolete forwarding, made constructor public, added JSON derived type attributes
`AgentResponseUpdateEvent.cs`	Changed base class from `ExecutorEvent` to `WorkflowOutputEvent`
`AgentResponseEvent.cs`	Changed base class from `ExecutorEvent` to `WorkflowOutputEvent`
`AIAgentHostExecutor.cs`	Updated to call `YieldOutputAsync()` instead of `AddEventAsync()` for agent events
`HandoffAgentExecutor.cs`	Updated to call `YieldOutputAsync()` instead of `AddEventAsync()` for agent events
`InProcessRunnerContext.cs`	Added special-case handling for `AgentResponse` and `AgentResponseUpdate` to create their specific event types
`TestWorkflowContext.cs`	Added special-case handling consistent with `InProcessRunnerContext`
`TestRunContext.cs`	Added special-case handling consistent with `InProcessRunnerContext`
`AgentEventsTests.cs`	New test file verifying the inheritance changes and regression test for issue #2938
Sample test files	Updated references from `SourceId` to `ExecutorId`

- Rename SourceId property to ExecutorId in WorkflowOutputEvent - Add [Obsolete] SourceId property for backward compatibility - Update all test usages to use ExecutorId Resolves part of #2938

- Change AgentResponseEvent and AgentResponseUpdateEvent to inherit from WorkflowOutputEvent instead of ExecutorEvent - Update AIAgentHostExecutor and HandoffAgentExecutor to use YieldOutputAsync() instead of AddEventAsync() for agent outputs - Add special-casing in InProcessRunnerContext.YieldOutputAsync() to create specific event types for AgentResponse and AgentResponseUpdate, bypassing OutputFilter for backwards compatibility - Update TestRunContext and TestWorkflowContext with same special-casing - Add regression tests in AgentEventsTests

lokitoth added the .NET label Jan 26, 2026

Copilot AI review requested due to automatic review settings January 26, 2026 16:33

lokitoth added workflows Related to Workflows in agent-framework breaking change Introduces changes that are not backward compatible and may require updates to dependent code. labels Jan 26, 2026

lokitoth temporarily deployed to integration January 26, 2026 16:33 — with GitHub Actions Inactive

Copilot started reviewing on behalf of lokitoth January 26, 2026 16:34 View session

Copilot AI reviewed Jan 26, 2026

View reviewed changes

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from 2332d2e to 3fe658a Compare January 26, 2026 16:58

lokitoth temporarily deployed to integration January 26, 2026 16:59 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from 3fe658a to 42a9908 Compare January 26, 2026 17:15

lokitoth temporarily deployed to integration January 26, 2026 17:15 — with GitHub Actions Inactive

lokitoth requested review from TaoChenOSU and moonbox3 January 26, 2026 17:32

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from 42a9908 to a8f2e72 Compare January 26, 2026 18:55

lokitoth temporarily deployed to integration January 26, 2026 18:56 — with GitHub Actions Inactive

lokitoth had a problem deploying to integration January 26, 2026 18:56 — with GitHub Actions Failure

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from a8f2e72 to f2093fe Compare January 27, 2026 21:41

lokitoth temporarily deployed to integration January 27, 2026 21:42 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from f2093fe to ecc489a Compare January 27, 2026 23:41

lokitoth temporarily deployed to integration January 27, 2026 23:41 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from ecc489a to 07b924f Compare February 4, 2026 18:05

lokitoth temporarily deployed to integration February 4, 2026 18:06 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from 07b924f to b0e7302 Compare February 4, 2026 18:23

lokitoth temporarily deployed to integration February 4, 2026 18:23 — with GitHub Actions Inactive

lokitoth temporarily deployed to integration February 17, 2026 16:29 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from 74f7f85 to acfee83 Compare February 17, 2026 18:11

lokitoth temporarily deployed to integration February 17, 2026 18:11 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from acfee83 to 1eae2b9 Compare February 18, 2026 14:21

lokitoth temporarily deployed to integration February 18, 2026 14:21 — with GitHub Actions Inactive

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from 1eae2b9 to f6225b5 Compare February 18, 2026 16:27

lokitoth temporarily deployed to integration February 18, 2026 16:28 — with GitHub Actions Inactive

westey-m approved these changes Feb 18, 2026

View reviewed changes

lokitoth added 3 commits February 18, 2026 12:59

Rename WorkflowOutputEvent.SourceId to ExecutorId for Python consistency

f334f4a

- Rename SourceId property to ExecutorId in WorkflowOutputEvent - Add [Obsolete] SourceId property for backward compatibility - Update all test usages to use ExecutorId Resolves part of #2938

refactor: Seal AgentResponse events

9f43c99

lokitoth force-pushed the dev/dotnet_workflow/unify_agent_response_event_in_output branch from f6225b5 to 9f43c99 Compare February 18, 2026 17:59

lokitoth temporarily deployed to integration February 18, 2026 17:59 — with GitHub Actions Inactive

lokitoth added this pull request to the merge queue Feb 18, 2026

github-merge-queue bot removed this pull request from the merge queue due to failed status checks Feb 18, 2026

lokitoth added this pull request to the merge queue Feb 18, 2026

Merged via the queue into main with commit 6a39d5a Feb 18, 2026
14 checks passed

github-project-automation bot moved this from In Review to Done in Agent Framework Feb 18, 2026

crickman deleted the dev/dotnet_workflow/unify_agent_response_event_in_output branch February 19, 2026 17:54

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

.NET: BREAKING: Unify `AgentResponse[Update]` events as `WorkflowOutputEvent`s#3441

.NET: BREAKING: Unify `AgentResponse[Update]` events as `WorkflowOutputEvent`s#3441
lokitoth merged 3 commits intomainfrom
dev/dotnet_workflow/unify_agent_response_event_in_output

lokitoth commented Jan 26, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

Conversation

lokitoth commented Jan 26, 2026

Motivation and Context

Description

Contribution Checklist

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants