Python: Fix WorkflowAgent to emit yield_output as agent response

[moonbox3]

Motivation and Context

WorkflowAgent created via .as_agent() was silently dropping WorkflowOutputEvent from ctx.yield_output() calls. The _convert_workflow_event_to_agent_update method only handled AgentRunUpdateEvent and RequestInfoEvent, ignoring workflow outputs.

Changes:

• Handle WorkflowOutputEvent in _convert_workflow_event_to_agent_update, converting it to AgentRunResponseUpdate
• Preserve content types: AgentRunResponseUpdate, ChatMessage, BaseContent subtypes (for example, TextContent, DataContent, UriContent), and strings
• Added unit tests for run(), run_stream(), various content types, and ChatMessage preservation

Description

• Fixes Python: WorkflowAgent created via .as_agent() does not emit outputs when using ctx.yield_output #2813

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.

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/core/agent_framework/_workflows
_agent.py	252	42	83%	60, 68–74, 102–103, 254, 295, 302, 371–374, 380, 386, 390–391, 394–400, 404–405, 444, 451, 457–458, 464, 476, 508, 515, 536, 543, 547, 558
TOTAL	16596	2568	84%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
2397	130 💤	0 ❌	0 🔥	57.348s ⏱️

[Copilot]

Pull request overview

This PR fixes a bug where WorkflowAgent created via .as_agent() was silently dropping WorkflowOutputEvent from ctx.yield_output() calls. The fix ensures that workflow outputs are properly converted to agent responses and surfaced to consumers.

Key Changes:

• Extended _convert_workflow_event_to_agent_update() to handle WorkflowOutputEvent and convert it to AgentRunResponseUpdate
• Added comprehensive test coverage for yield_output() functionality including different content types and streaming scenarios

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
python/packages/core/agent_framework/_workflows/_agent.py	Added handling for WorkflowOutputEvent in the event conversion method, with support for multiple data types (AgentRunResponseUpdate, ChatMessage, BaseContent subtypes, and strings)
python/packages/core/tests/workflow/test_workflow_agent.py	Added four new test methods covering yield_output behavior in non-streaming mode, streaming mode, with various content types (TextContent, DataContent, UriContent), and with ChatMessage preservation