[BREAKING] Python: Add factory pattern to GroupChat and Magentic

[TaoChenOSU]

Motivation and Context

This completes #429

Description

1. Add participant factory and orchestrator factory to group chat.
2. Add participant factory and manager factory to Magentic.
3. BREAKING: Rename with_standard_manager to with_manager since the API supports non-standard magentic manager implementations.
4. BREAKING: Rename the participant_factories API to register_participant to align with the rest of the orchestrations.
5. Tests and samples.

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 adds factory pattern support to GroupChat and Magentic workflow builders, enabling reusable builder instances for creating multiple workflows with fresh agent instances. The PR also renames with_standard_manager to with_manager to better support both standard and custom manager implementations.

Changes:

• Added register_participants() and factory support for participant creation in GroupChatBuilder and MagenticBuilder
• Added manager_factory and agent_factory options to MagenticBuilder's with_manager() method
• Added orchestrator_factory option to GroupChatBuilder's with_orchestrator() method
• Renamed with_standard_manager() to with_manager() across all samples and tests
• Consolidated orchestrator configuration methods in GroupChatBuilder into a single with_orchestrator() method

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
python/packages/core/agent_framework/_workflows/_magentic.py	Added participant and manager factory support to MagenticBuilder; renamed with_standard_manager to with_manager
python/packages/core/agent_framework/_workflows/_group_chat.py	Added participant and orchestrator factory support; consolidated with_agent_orchestrator and with_select_speaker_func into with_orchestrator
python/packages/core/agent_framework/_workflows/_handoff.py	Renamed participant_factories() to register_participants() for API consistency
python/packages/core/agent_framework/_workflows/_sequential.py	Updated error messages for consistency
python/packages/core/agent_framework/_workflows/_concurrent.py	Updated error messages for consistency
python/packages/core/tests/workflow/test_magentic.py	Added comprehensive factory tests and updated all method calls
python/packages/core/tests/workflow/test_group_chat.py	Added comprehensive factory tests and updated all method calls
python/packages/core/tests/workflow/test_handoff.py	Updated method calls to use register_participants()
python/packages/core/tests/workflow/test_workflow_kwargs.py	Updated method calls to new API
python/samples/*	Updated all sample code to use the new API

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/core/agent_framework/_workflows
_concurrent.py	190	29	84%	53, 62–63, 71–72, 91–92, 97, 102, 127, 132, 137–138, 144, 166, 176, 183, 350, 353, 381, 437, 449, 488, 490–491, 493, 498, 520, 524
_group_chat.py	289	38	86%	55, 172, 333, 340, 367, 378–379, 385, 390, 406, 433–438, 440, 473–476, 478, 483–487, 667, 675, 693, 771, 777, 822, 842, 938, 957, 976, 986
_handoff.py	384	58	84%	58, 110–111, 113, 142–143, 163–173, 175, 177, 179, 184, 284, 338, 363, 389, 397–398, 412, 461–462, 492, 539–541, 724, 731, 736, 823, 826, 835–838, 848, 853, 860, 866–869, 904, 909, 1106, 1109, 1117, 1135, 1142, 1217
_magentic.py	618	93	84%	43, 48, 70–79, 84, 88–99, 264, 275, 279, 299, 360, 369, 371, 413, 430, 439–440, 442–444, 446, 457, 599, 601, 641, 689, 725–727, 729, 737–740, 744–747, 790, 817–820, 911, 917, 923, 962, 1000, 1029, 1046, 1057, 1111–1112, 1116–1118, 1142, 1163–1164, 1177, 1193, 1215, 1263–1264, 1302–1303, 1459, 1468, 1471, 1476, 1872, 1914, 1929, 1958
_sequential.py	108	12	88%	74, 166, 184, 195, 201, 238, 240–241, 243, 248, 270, 274
TOTAL	17500	2625	85%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3178	213 💤	0 ❌	0 🔥	1m 3s ⏱️

[TaoChenOSU]

Doc PR: https://github.com/MicrosoftDocs/semantic-kernel-pr/pull/820